This is a list of my publications in reverse chronological order. All publication fields are searchable (i.e., authors, paper title, journal/venue, year, abstract, etc).

The documents listed have been provided as a means to ensure timely dissemination of scholarly and technical work. Copyright and all rights of listed publications are maintained by the authors or publication as noted. These works may not be copied for commercial redistribution, republication, dissemination, or reposting without the explicit permission of the copyright holder.

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► V. Manousaki, K. Papoutsakis and A.A. Argyros, "Evaluating Method Design Options for Action Classification based on Bags of Visual Words", In International Conference on Computer Vision Theory and Applications (VISAPP 2018), (to appear), Scitepress, Madeira, Portugal, January 2018. [Abstract] [BibTeX]
Abstract: The Bags of VisualWords (BoVW) framework has been applied successfully to several computer vision tasks. In this work we are particularly interested on its application to the problem of action recognition/classification. The key design decisions for a method that follows the BoVW framework are (a) the visual features to be employed, (b) the size of the codebook to be used for representing a certain action and (c) the classifier applied to the developed representation to solve the classification task. We perform several experiments to investigate a variety of options regarding all the aforementioned design parameters. We also propose a new feature type and we suggest a method that determines automatically the size of the codebook. The experimental results show that our proposals produce results that are competitive to the outcomes of state of the art methods.
BibTeX:
@inproceedings{ManousakiPapoutsakisArgyros2018,
  author = {Manousaki, Victoria and Papoutsakis, Konstantinos and Argyros, Antonis A},
  title = {Evaluating Method Design Options for Action Classification based on Bags of Visual Words},
  booktitle = {International Conference on Computer Vision Theory and Applications (VISAPP 2018), (to appear)},
  publisher = {Scitepress},
  year = {2018},
  month = {January},
  address = {Madeira, Portugal},
  projects =  {Co4Robots,ACANTO}
}
► C. Hernandez-Matas, X. Zabulis, A. Triantafyllou, P. Anyfanti, S. Douma and A.A. Argyros, "FIRE: Fundus Image Registration Dataset", Journal for Modeling in Opthalmology, Kugler Publications, vol. 1, no. 4, pp. 16-28, 2017. [Abstract] [BibTeX] [PDF] [URL]
Abstract: Purpose: Retinal image registration is a useful tool for medical professionals. However, accuracy evaluation of registration methods has not been consistently assessed in the literature. Toaddress that, a dataset comprised of retinal imagepairs annotated with ground truth and an evaluation protocol for registration methods is proposed. Methods: The dataset is comprised by 134 retinal fundus image pairs. These pairs are classified into three categories, according to characteristics that are relevant to indicative registration applications. Such characteristics are the degree of overlap between images and the presence/absence of anatomical dierences. Ground truth in the form of corresponding image points and a protocol to evaluate registration accuracy are provided. Results: Using the aforementioned protocol it is shownthat FIRE enables quantitative and comparative evaluation of retinal registration methods under a variety of conditions. Conclusion: This work enables the fair comparison of retinal registration methods. It also helps researchers to select the registration method that is most appropriate given a specific target use.
BibTeX:
@article{Hernandez-MatasZabulisTriantafyllouEtAl2016a,
  author = {Hernandez-Matas, Carlos and Zabulis, Xenophon and Triantafyllou, Areti and Anyfanti, Panagiota and Douma, S and Argyros, Antonis A},
  title = {FIRE: Fundus Image Registration Dataset},
  journal = {Journal for Modeling in Opthalmology},
  publisher = {Kugler Publications},
  year = {2017},
  volume = {1},
  number = {4},
  pages = {16-28},
  url = {http://www.ics.forth.gr/cvrl/fire/},
  projects =  {REVAMMAD},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2017_journal_firedataset.pdf}
}
► T.-H. Pham, N. Kyriazis, A.A. Argyros and A. Kheddar, "Hand-Object Contact Force Estimation From Markerless Visual Tracking", IEEE Transactions on Pattern Analysis and Machine Intelligence (to appear), IEEE, October 2017. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: Abstract—We consider the problem of estimating realistic contact forces during manipulation, backed with ground-truth measurements, using vision alone. Interaction forces are usually measured by mounting force transducers onto the manipulated objects or the hands. Those are costly, cumbersome, and alter the objects’ physical properties and their perception by the human sense of touch. Our work establishes that interaction forces can be estimated in a cost-effective, reliable, non-intrusive way using vision. This is a complex and challenging problem. Indeed, in multi-contact, a given motion can generally be caused by an infinity of possible force distributions. To alleviate the limitations of traditional models based on inverse optimization, we collect and release the first large-scale dataset on manipulation kinodynamics as 3:2 hours of synchronized force and motion measurements under 193 object-grasp
configurations. We learn a mapping between high-level kinematic features based on the equations of motion and the underlying manipulation forces using recurrent neural networks (RNN). The RNN predictions are consistently refined using physics-based optimization through second-order cone programming (SOCP). We show that our method can successfully capture interaction forces compatible with both the observations and the way humans intuitively manipulate objects, using a single RGB-D camera.
BibTeX:
@article{PhamKyriazisArgyrosKheddar2018,
  author = {Pham, Tu-Hoa and Kyriazis, Nikolaos and Argyros, Antonis A and Kheddar, Abderrahmane},
  title = {Hand-Object Contact Force Estimation From Markerless Visual Tracking},
  journal = {IEEE Transactions on Pattern Analysis and Machine Intelligence (to appear)},
  publisher = {IEEE},
  year = {2017},
  month = {October},
  url = {http://ieeexplore.ieee.org/document/8085141/},
  projects =  {ROBOHOW,WEARHAP},
  doi = {10.1109/TPAMI.2017.2759736},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2018_journal_PAMI_fsv.pdf},
  videolink = {https://youtu.be/NhNV3tCcbd0}
}
► P. Panteleris and A.A. Argyros, "Back to RGB: 3D tracking of hands and hand-object interactions based on short-baseline stereo", In IEEE International Conference on Computer Vision Workshops (HANDS 2017 - ICCVW 2017). Also available at arxiv., IEEE, pp. 575-584, Venice, Italy, October 2017. [Abstract] [BibTeX] [PDF] [URL] [VIDEO]
Abstract: We present a novel solution to the problem of 3D tracking of the articulated motion of human hand(s), possibly in interaction with other objects. The vast majority of contemporary relevant work capitalizes on depth information provided by RGBD cameras. In this work, we show that accurate and efficient 3D hand tracking is possible, even for the case of RGB stereo. A straightforward approach for solving the problem based on such input would be to first recover depth and then apply a state of the art depth-based 3D hand tracking method. Unfortunately, this does not work well in practice because the stereo-based, dense 3D reconstruction of hands is far less accurate than the one obtained by RGBD cameras. Our approach bypasses 3D reconstruction and follows a completely different route: 3D hand tracking is formulated as an optimization problem whose solution is the hand configuration that maximizes the color consistency between the two views of the hand. We demonstrate the applicability of our method for real time tracking of a single hand, of a hand manipulating an object and of two interacting hands. The method has been evaluated quantitatively on standard datasets and in comparison to relevant, state of the art RGBD-based approaches. The obtained results demonstrate that the proposed stereo-based method performs equally well to its RGBD-based competitors, and in some cases, it even outperforms them.
BibTeX:
@inproceedings{PantelerisArgyros2017,
  author = {Panteleris, Paschalis and Argyros, Antonis A},
  title = {Back to RGB: 3D tracking of hands and hand-object interactions based on short-baseline stereo},
  booktitle = {IEEE International Conference on Computer Vision Workshops (HANDS 2017 - ICCVW 2017). Also available at arxiv.},
  publisher = {IEEE},
  year = {2017},
  month = {October},
  pages = {575--584},
  address = {Venice, Italy},
  url = {http://openaccess.thecvf.com/content_ICCV_2017_workshops/w11/html/Panteleris_Back_to_RGB_ICCV_2017_paper.html},
  projects =  {Co4Robots,WEARHAP},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2017_10_HANDS_StereoHandTracking.pdf},
  videolink = {https://youtu.be/yf3TKCjLD00}
}
► K. Roditakis, A. Makris and A.A. Argyros, "Generative 3D Hand Tracking with Spatially Constrained Pose Sampling", In British Machine Vision Conference (BMVC 2017), BMVA, London, UK, September 2017. [Abstract] [BibTeX] [PDF] [URL] [VIDEO]
Abstract: We present a method for 3D hand tracking that exploits spatial constraints in the form of end effector (fingertip) locations. The method follows a generative, hypothesize-and-test approach and uses a hierarchical particle filter to track the hand. In contrast to state of the art methods that consider spatial constraints in a soft manner, the proposed approach enforces constraints during the hand pose hypothesis generation phase by sampling in the sl Reachable Distance Space (RDS). This sampling produces hypotheses that respect both the hands' dynamics and the end effector locations. The data likelihood term is calculated by measuring the discrepancy between the rendered 3D model and the available observations. Experimental results on challenging, ground truth-annotated sequences containing severe hand occlusions demonstrate that the proposed approach outperforms the state of the art in hand tracking accuracy.
BibTeX:
@inproceedings{RoditakisMakrisArgyros2017,
  author = {Roditakis, Konstantinos and Makris, Alexandros and Argyros, Antonis A},
  title = {Generative 3D Hand Tracking with Spatially Constrained Pose Sampling},
  booktitle = {British Machine Vision Conference (BMVC 2017)},
  publisher = {BMVA},
  year = {2017},
  month = {September},
  address = {London, UK},
  url = {http://users.ics.forth.gr/ argyros/res_handRDS.html},
  projects =  {WEARHAP, CO4ROBOTS},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2017_09_BMVC_RDSRoditak.pdf},
  videolink = {https://youtu.be/DdXA-fslgpI}
}
► C. Hernandez-Matas, X. Zabulis and A.A. Argyros, "An Experimental Evaluation of the Accuracy of Keypoints-based Retinal Image Registration", In IEEE Engineering in Medicine and Biology Conference (EMBC 2017), IEEE, pp. 377-381, JeJu island, S. Korea, July 2017. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: This work regards an investigation of the accuracy of a state-of-the-art, keypoint-based retinal image registration approach, as to the type of keypoint features used to guide the registration process. The employed registration approach is a local method that incorporates the notion of a 3D retinal surface imaged from different viewpoints and has been shown, experimentally, to be more accurate than competing approaches. The correspondences obtained between SIFT, SURF, Harris-PIIFD and vessel bifurcations are studied, either individually or in combinations. The combination of SIFT features with vessel bifurcations was found to perform better than other combinations or any individual feature type, alone. The registration approach is also comparatively evaluated against representative methods of the state-of-the-art in retinal image registration, using a benchmark dataset that covers a broad range of cases regarding the overlap of the acquired images and the anatomical characteristics of the imaged retinas.
BibTeX:
@inproceedings{Hernandez-Matas2017,
  author = {Hernandez-Matas, Carlos and Zabulis, Xenophon and Argyros, Antonis A},
  title = {An Experimental Evaluation of the Accuracy of Keypoints-based Retinal Image Registration},
  booktitle = {IEEE Engineering in Medicine and Biology Conference (EMBC 2017)},
  publisher = {IEEE},
  year = {2017},
  month = {July},
  pages = {377--381},
  address = {JeJu island, S. Korea},
  url = {https://doi.org/10.1109/EMBC.2017.8036841},
  projects =  {REVAMMAD},
  doi = {10.1109/EMBC.2017.8036841},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2017_07_EMBC_cues.pdf}
}
► K. Papoutsakis, C. Panagiotakis and A.A. Argyros, "Temporal Action Co-Segmentation in 3D Motion Capture Data and Videos", In IEEE Computer Vision and Pattern Recognition (CVPR 2017), IEEE, pp. 2146-2155, Honolulu, Hawaii, USA, July 2017. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: Given two action sequences, we are interested in spotting/co-segmenting all pairs of sub-sequences that represent the same action. We propose a totally unsupervised solution to this problem. No a-priori model of the actions is assumed to be available. The number of common subsequences may be unknown. The sub-sequences can be located anywhere in the original sequences, may differ in duration and the corresponding actions may be performed by a different person, in different style. We treat this type of temporal action co-segmentation as a stochastic optimization problem that is solved by employing Particle Swarm Optimization (PSO). The objective function that is minimized by PSO capitalizes on Dynamic TimeWarping (DTW) to compare two action sequences. Due to the generic problem formulation and solution, the proposed method can be applied to motion capture (i.e., 3D skeletal) data or to conventional RGB video data acquired in the wild. We present extensive quantitative experiments on several standard, ground truthed datasets. The obtained results demonstrate that the proposed method achieves a remarkable increase in co-segmentation quality compared to all tested existing state of the art methods.
BibTeX:
@inproceedings{PapoutsakisPanagiotakisArgyros2017,
  author = {Papoutsakis, Konstantinos and Panagiotakis, Costas and Argyros, Antonis A},
  title = {Temporal Action Co-Segmentation in 3D Motion Capture Data and Videos},
  booktitle = {IEEE Computer Vision and Pattern Recognition (CVPR 2017)},
  publisher = {IEEE},
  year = {2017},
  month = {July},
  pages = {2146--2155},
  address = {Honolulu, Hawaii, USA},
  url = {http://www.ics.forth.gr/cvrl/evaco/},
  projects =  {ACANTO, Co4Robots},
  doi = {10.1109/CVPR.2017.231},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2017_07_CVPR_cosegmentation.pdf},
  videolink = {https://youtu.be/YH3QdthVDvQ}
}
► D. Michel, A. Qammaz and A.A. Argyros, "Markerless 3D Human Pose Estimation and Tracking based on RGBD Cameras: an Experimental Evaluation", In International Conference on Pervasive Technologies Related to Assistive Environments (PETRA 2017), ACM, pp. 115-122, Rhodes, Greece, June 2017. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: We present a comparative experimental evaluation of three methods that estimate the 3D position, orientation and articulation of the human body from markerless visual observations obtained by RGBD cameras. The evaluated methods are representatives of three broad 3D human pose estimation/tracking methods. Specifically, the first is the discriminative approach adopted by OpenNI. The second is a hybrid approach that depends on the input of two synchronized and extrinsically calibrated RGBD cameras. Finally, the third one is a recently developed generative method that depends on input provided by a single RGBD camera. The experimental evaluation of these methods has been based on a publicly available data set that is annotated with ground truth. The obtained results expose the characteristics of the three methods and provide evidence that can guide the selection of the most appropriate one depending on the requirements of a certain application domain.
BibTeX:
@inproceedings{MichelQammazArgyros2017,
  author = {Michel, Damien and Qammaz, Ammar and Argyros, Antonis A},
  title = {Markerless 3D Human Pose Estimation and Tracking based on RGBD Cameras: an Experimental Evaluation},
  booktitle = {International Conference on Pervasive Technologies Related to Assistive Environments (PETRA 2017)},
  publisher = {ACM},
  year = {2017},
  month = {June},
  pages = {115--122},
  address = {Rhodes, Greece},
  url = {http://users.ics.forth.gr/ argyros/res_fhbt.html},
  projects =  {WEARHAP, ACANTO},
  doi = {10.1145/3056540.3056543},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2017_06_PETRA_skeletons.pdf},
  videolink = {http://cvrlcode.ics.forth.gr/projects/fhbt/}
}
► C. Hernandez-Matas, X. Zabulis, A. Triantafyllou, P. Anyfanti and A.A. Argyros, "Retinal Image Registration under the Assumption of a Spherical Eye", Computerized Medical Imaging and Graphics, Special Issue on Ophthalmic Medical Image Analysis, Elsevier, vol. 55, pp. 95-105, January 2017. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: We propose a method for registering a pair of retinal images. The proposed approach employs point correspondences and assumes that the human eye has a spherical shape. The image registration problem is formulated as a 3D pose estimation problem, solved by estimating the rigid transformation that relates the views from which the two images were acquired. Given this estimate, each image can be warped upon the other so that pixels with the same coordinates image the same retinal point. Extensive experimental evaluation shows improved accuracy over state of the art methods, as well as robustness to noise and spurious keypoint matches. Experiments also indicate the method's applicability to the comparative analysis of images from different examinations that may exhibit changes and its applicability to diagnostic support.
BibTeX:
@article{Hernandez-MatasZabulisTriantafyllouEtAl2017b,
  author = {Hernandez-Matas, Carlos and Zabulis, Xenophon and Triantafyllou, Areti and Anyfanti, Panagiota and Argyros, Antonis A},
  title = {Retinal Image Registration under the Assumption of a Spherical Eye},
  journal = {Computerized Medical Imaging and Graphics, Special Issue on Ophthalmic Medical Image Analysis},
  publisher = {Elsevier},
  year = {2017},
  month = {January},
  volume = {55},
  pages = {95--105},
  projects =  {REVAMMAD},
  doi = {10.1016/j.compmedimag.2016.06.006},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2017_journal_SMIG_CarlosSpherical.pdf}
}
► S. Ciotti, E. Battaglia, I. Oikonomidis, A. Makris, A. Tsoli, A. Bicchi, A.A. Argyros and M. Bianchi, "Synergy-driven Performance Enhancement of Vision-based 3D Hand Pose Reconstruction", In International Conference on Wireless Mobile Communication and Healthcare (MobiHealth 2016), special session on advances in soft wearable technology for mobile-health, EAI, pp. 328-336, Milan, Italy, November 2016. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: In this work we propose, for the first time, to improve the performance of a hand pose reconstruction (HPR) technique from RGBD camera data, which is affected by self-occlusions, leveraging upon postural synergy information, i.e., a priori information on how human most commonly use and shape their hands in everyday life tasks. More specifically, in our approach, we ignore joint angle values estimated with low confidence through a vision-based HPR technique and fuse synergistic information with such incomplete measures. Preliminary experiments are reported showing the effectiveness of the proposed integration.
BibTeX:
@inproceedings{CiottiBattagliaOikonomidisEtAl2016a,
  author = {Ciotti, Simone and Battaglia, Edoardo and Oikonomidis, Iason and Makris, Alexandros and Tsoli, Aggeliki and Bicchi, Antonio and Argyros, Antonis A and Bianchi, Matteo},
  title = {Synergy-driven Performance Enhancement of Vision-based 3D Hand Pose Reconstruction},
  booktitle = {International Conference on Wireless Mobile Communication and Healthcare (MobiHealth 2016), special session on advances in soft wearable technology for mobile-health},
  publisher = {EAI},
  year = {2016},
  month = {November},
  pages = {328-336},
  address = {Milan, Italy},
  projects =  {WEARHAP},
  doi = {10.1007/978-3-319-58877-3},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2016_11_MobiHealth_synergies.pdf}
}
► A. Tsoli and A.A. Argyros, "Tracking deformable surfaces that undergo topological changes using an RGB-D camera", In International Conference on 3D Vision (3DV 2016), pp. 333-341, Stanford University, California, USA, October 2016. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: We present a method for 3D tracking of deformable surfaces with dynamic topology, for instance a paper that undergoes cutting or tearing. Existing template-based methods assume a template of fixed topology. Thus, they fail in tracking deformable objects that undergo topological changes. In our work, we employ a dynamic template (3D mesh) whose topology evolves based on the topological changes of the observed geometry. Our tracking framework deforms the defined template based on three types of constraints (a) the surface of the template has to be registered to the 3D shape of the tracked surface, (b) the template deformation should respect feature (SIFT) correspondences between selected pairs of frames and, (c) the lengths of the template edges should be preserved. The latter constraint is relaxed when an edge is found to lie on a “geometric gap”, that is, when a significant depth discontinuity is detected along this edge. The topology of the template is updated on the fly by removing overstretched edges that lie on a geometric gap. The proposed method has been evaluated quantitatively and qualitatively in both synthetic and real sequences of monocular RGB-D views of surfaces that undergo various types of topological changes. The obtained results show that our approach tracks effectively objects with evolving topology and outperforms state of the art methods in tracking accuracy.
BibTeX:
@inproceedings{TsoliArgyros2016a,
  author = {Tsoli, Aggeliki and Argyros, Antonis A},
  title = {Tracking deformable surfaces that undergo topological changes using an RGB-D camera},
  booktitle = {International Conference on 3D Vision (3DV 2016)},
  year = {2016},
  month = {October},
  pages = {333--341},
  address = {Stanford University, California, USA},
  url = {http://www.ics.forth.gr/cvrl/tearing},
  projects =  {WEARHAP,ROBOHOW},
  doi = {10.1109/3DV.2016.42},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2016_10_3dv_tearing.pdf},
  videolink = {https://youtu.be/Hxa7nKUvsso}
}
► G. Karvounas, I. Oikonomidis and A.A. Argyros, "Localizing Periodicity in Time Series and Videos", In British Machine Vision Conference (BMVC 2016), BMVA, York, UK, September 2016. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: Periodicity detection is a problem that has received a lot of attention, thus several important tools exist to analyse purely periodic signals. However, in many real world scenarios (time series, videos of human activities, etc) periodic signals appear in the context of non-periodic ones. In this work we propose a method that, given a time series representing a periodic signal that has a non-periodic prefix and tail, estimates the start, the end and the period of the periodic part of the signal. We formulate this as an optimization problem that is solved based on evolutionary optimization techniques. Quantitative experiments on synthetic data demonstrate that the proposed method is successful in localizing the periodic part of a signal and exhibits robustness in the presence of noisy measurements. Also, it does so even when the periodic part of the signal is too short compared to its non-periodic prefix and tail. We also provide quantitative and qualitative results obtained from the application of the proposed method to the problem of unsupervised localization and segmentation of periodic activities in real world videos.
BibTeX:
@inproceedings{KarvounasOikonomidisArgyros2016a,
  author = {Karvounas, Giorgos and Oikonomidis, Iason and Argyros, Antonis A},
  title = {Localizing Periodicity in Time Series and Videos},
  booktitle = {British Machine Vision Conference (BMVC 2016)},
  publisher = {BMVA},
  year = {2016},
  month = {September},
  address = {York, UK},
  url = {http://users.ics.forth.gr/ argyros/res_periodicity.html},
  projects =  {ACANTO},
  doi = {10.5220/0005800300450052},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2016_09_bmvc_periodicity.pdf},
  videolink = {https://youtu.be/2oa0Y9znH6g}
}
► C. Hernandez-Matas, X. Zabulis and A.A. Argyros, "Retinal Image Registration Through Simultaneous Camera Pose and Eye Shape Estimation", In IEEE Engineering in Medicine and Biology Conference (EMBC 2016), IEEE, pp. 3247-3251, Orlando, Florida, USA, August 2016. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: In this paper, a retinal image registration method is proposed. The approach utilizes keypoint correspondences and assumes that the human eye has a spherical or ellipsoidal shape. The image registration problem amounts to solving a camera 3D pose estimation problem and, simultaneously, an eye 3D shape estimation problem. The camera pose estimation problem is solved by estimating the relative pose between the views from which the images were acquired. The eye shape estimation problem parameterizes the shape and orientation of an ellipsoidal model for the eye. Experimental evaluation shows 17.91% reduction of registration error and 47.52% reduction of the error standard deviation over state of the art methods.
BibTeX:
@inproceedings{Hernandez-MatasZabulisArgyros2016a,
  author = {Hernandez-Matas, Carlos and Zabulis, Xenophon and Argyros, Antonis A},
  title = {Retinal Image Registration Through Simultaneous Camera Pose and Eye Shape Estimation},
  booktitle = {IEEE Engineering in Medicine and Biology Conference (EMBC 2016)},
  publisher = {IEEE},
  year = {2016},
  month = {August},
  pages = {3247--3251},
  address = {Orlando, Florida, USA},
  projects =  {REVAMMAD},
  doi = {10.1109/EMBC.2016.7591421},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2016_08_embc_ellipsoidal.pdf}
}
► D. Kosmopoulos, K. Papoutsakis and A.A. Argyros, "A framework for online segmentation and classification of modeled actions performed in the context of unmodeled ones", IEEE Transactions on Circuits and Systems for Video Technology (TCSVT) (to appear), July 2016. [Abstract] [BibTeX] [DOI] [URL]
Abstract: In this work, we propose a discriminative framework for online simultaneous segmentation and classification of modeled visual actions that can be performed in the context of other, unknown actions. To this end, we employ Hough transform to vote in a 3D space for the begin point, the end point and the label of the segmented part of the input stream. An SVM is used to model each class and to suggest putative labeled segments on the timeline. To identify the most plausible segments among the putative ones we apply a dynamic programming algorithm, which maximises the likelihood for label assignment in linear time. The performance of our method is evaluated on synthetic, as well as on real data (Weizmann, TUM Kitchen, UTKAD and Berkeley multimodal human action databases). Extensive quantitative results obtained on a number of standard datasets demonstrate that the proposed approach is of comparable accuracy to the state of the art for online stream segmentation and classification when all performed actions are known and performs considerably better in the presence of unmodeled actions.
BibTeX:
@article{KosmopoulosPapoutsakisArgyros2016a,
  author = {Kosmopoulos, Dimitrios and Papoutsakis, Konstantinos and Argyros, Antonis A},
  title = {A framework for online segmentation and classification of modeled actions performed in the context of unmodeled ones},
  journal = {IEEE Transactions on Circuits and Systems for Video Technology (TCSVT) (to appear)},
  year = {2016},
  month = {July},
  url = {http://users.ics.forth.gr/ argyros/res_actions.html},
  projects =  {HOBBIT,ROBOHOW,ACANTO},
  doi = {10.1109/TCSVT.2016.2589678}
}
► G. Park, A.A. Argyros and W. Woo, "Efficient 3D Hand Tracking in Articulation Subspaces for the Manipulation of Virtual Objects", In Computer Graphics International (CGI 2016), ACM, pp. 33-36, Hersonissos, Crete, Greece, June 2016. [Abstract] [BibTeX] [DOI] [PDF] [VIDEO]
Abstract: We propose an efficient method for model-based 3D tracking of hand articulations observed from an egocentric viewpoint that aims at supporting the manipulation of virtual objects. Previous model-based approaches optimize non-convex objective functions defined in the 26 Degrees of Freedom (DoFs) space of possible hand articulations. In our work, we decompose this space into six lower dimensional spaces (6 DoFs for the palm and 4 DoFs for each finger). We also label each finger with a Gaussian model that is propagated between successive image frames. As confirmed by a number of experiments, this divide-and-conquer approach tracks hand articulations more accurately than existing model-based approaches. At the same time, real time performance is achieved without the need of GPGPU processing. Additional experiments show that the proposed approach is preferable for supporting the accurate manipulation of virtual objects in VR/AR scenarios.
BibTeX:
@inproceedings{ParkArgyrosWoo2016a,
  author = {Park, Gabyong and Argyros, Antonis A and Woo, Woontack},
  title = {Efficient 3D Hand Tracking in Articulation Subspaces for the Manipulation of Virtual Objects},
  booktitle = {Computer Graphics International (CGI 2016)},
  publisher = {ACM},
  year = {2016},
  month = {June},
  pages = {33--36},
  address = {Hersonissos, Crete, Greece},
  projects =  {WEARHAP},
  doi = {10.1145/2949035.2949044},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2016_06_CGI_park.pdf},
  videolink = {https://youtu.be/9sU2HAvnCKQ}
}
► C. Panagiotakis and A.A. Argyros, "Parameter-free modelling of 2D shapes with ellipses", Pattern Recognition, Elsevier, vol. 53, pp. 259-275, May 2016. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: Our goal is to represent a given 2D shape with an automatically determined number of ellipses, so that the total area covered by the ellipses is equal to the area of the original shape without any assumption or prior knowledge about the object structure. To solve this interesting theoretical problem, first we employ the skeleton of the 2D shape which provides important information on the parameters of the ellipses that could approximate the original shape. For a given number of such ellipses, the hard Expectation-Maximization (EM) algorithm is employed to maximise the shape coverage under the equal area constraint. Different models (i.e., solutions involving different numbers of ellipses) are evaluated based on the Akaike Information Criterion (AIC). This considers a novel, entropy-based shape complexity measure that balances the model complexity and the model approximation error. In order to minimise the AIC criterion, two variants are proposed and evaluated: (a) the augmentative method that gradually increases the number of considered ellipses starting from a single one and, (b) the decremental method that decreases the number of ellipses starting from a large, automatically defined set. The obtained quantitative results on more than 4,000 2D shapes included in standard as well as in custom datasets, quantify the performance of the proposed methods and illustrate that their solutions agree with human intuition.
BibTeX:
@article{PanagiotakisArgyros2016a,
  author = {Panagiotakis, Costas and Argyros, Antonis A},
  title = {Parameter-free modelling of 2D shapes with ellipses},
  journal = {Pattern Recognition},
  publisher = {Elsevier},
  year = {2016},
  month = {May},
  volume = {53},
  pages = {259--275},
  url = {https://sites.google.com/site/costaspanagiotakis/research/EFA},
  projects =  {WEARHAP},
  doi = {10.1016/j.patcog.2015.11.004},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2015_journal_pr_ellipses.pdf}
}
► P. Panteleris and A.A. Argyros, "Monitoring and Interpreting Human Motion to Support Clinical Applications of a Smart Walker", In Workshop on Human Motion Analysis for Healthcare Applications (HMAHA 2016), IET, London, UK, May 2016. [Abstract] [BibTeX] [PDF] [URL] [VIDEO]
Abstract: We present two proof-of-concept applications of human motion perception technologies for automating clinical tests performed by the FriWalk smart walker. FriWalk is a robotic walker currently being developed in the context of the EU H2020 project ACANTO that is designed to operate in a personal or a clinical mode. The goal of the clinical FriWalk is to support/automate clinical tests and rehabilitation of patients with mobility problems.
BibTeX:
@inproceedings{PantelerisArgyros2016a,
  author = {Panteleris, Paschalis and Argyros, Antonis A},
  title = {Monitoring and Interpreting Human Motion to Support Clinical Applications of a Smart Walker},
  booktitle = {Workshop on Human Motion Analysis for Healthcare Applications (HMAHA 2016)},
  publisher = {IET},
  year = {2016},
  month = {May},
  address = {London, UK},
  url = {http://users.ics.forth.gr/ argyros/res_fhbt.html},
  projects =  {ACANTO},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2016_05_IETWorkshop_acanto.pdf},
  videolink = {https://youtu.be/YkyJsIW7FVM}
}
► M. Foukarakis, I. Adami, D. Ioannidi, A. Leonidis, D. Michel, A. Qammaz, K. Papoutsakis, M. Antona and A.A. Argyros, "A Robot-based Application for Physical Exercise Training", In International Conference on Information and Communication Technologies for Ageing Well and e-Health (ICT4AWE 2016), Scitepress, pp. 45-52, Rome, Italy, April 2016. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: According to studies, performing physical exercise is beneficial for reducing the risk of falling in the elderly and prolonging their stay at home. In addition, regular exercising helps cognitive function and increases positive behaviour for seniors with cognitive impairment and dementia. In this paper, a fitness application integrated into a service robot is presented. Its aim is to motivate the users to perform physical training by providing relevant exercises and useful feedback on their progress. The application utilizes the robot vision system to track and recognize user movements and activities and supports multimodal interaction with the user. The pa-per describes the design challenges, the system architecture, the user interface and the human motion capturing module. Additionally, it discusses some results from user testing in laboratory and home-based trials.
BibTeX:
@inproceedings{FoukarakisAdamiIoannidiEtAl2016a,
  author = {Foukarakis, Michael and Adami, Ilia and Ioannidi, Danae and Leonidis, Asterios and Michel, Damien and Qammaz, Ammar and Papoutsakis, Konstantinos and Antona, Margherita and Argyros, Antonis A},
  title = {A Robot-based Application for Physical Exercise Training},
  booktitle = {International Conference on Information and Communication Technologies for Ageing Well and e-Health (ICT4AWE 2016)},
  publisher = {Scitepress},
  year = {2016},
  month = {April},
  pages = {45--52},
  address = {Rome, Italy},
  url = {http://users.ics.forth.gr/ argyros/res_fhbt.html},
  projects =  {HOBBIT},
  doi = {10.5220/0005800300450052},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2016_04_ICT4AWE_fitness.pdf}
}
► D. Michel and A.A. Argyros, "Apparatuses, methods and systems for recovering a 3-dimensional skeletal model of the human body", United States Patent No 20160086350, Filed: 22 September, 2015, Published: 24 March, 2016. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: The ARS offers tracking, estimation of position, orientation and full articulation of the human body from marker-less visual observations obtained by a camera, for example an RGBD camera. An ARS may provide hypotheses of the 3D configuration of body parts or the entire body from a single depth frame. The ARS may also propagates estimations of the 3D configuration of body parts and the body by mapping or comparing data from the previous frame and the current frame. The ARS may further compare the estimations and the hypotheses to provide a solution for the current frame. An ARS may select, merge, refine, and/or otherwise combine data from the estimations and the hypotheses to provide a final estimation corresponding to the 3D skeletal data and may apply the final estimation data to capture parameters associated with a moving or still body.
BibTeX:
@patent{MichelArgyros2016a,
  author = {Michel, Damien and Argyros, Antonis A}, 
  title = {Apparatuses, methods and systems for recovering a 3-dimensional skeletal model of the human body}, 
  nationality = {United States}, 
  number = {20160086350}, 
  year = {2016}, 
  month = {March}, 
  day = {24}, 
  yearfiled = {2015}, 
  monthfiled = {September}, 
  dayfiled = {22}, 
  url = {http://users.ics.forth.gr/ argyros/res_fhbt.html}, 
  projects =  {WEARHAP,ROBOHOW,ACANTO},
  doi = {http://www.freepatentsonline.com/y2016/0086350.html},
  pdflink = {http://www.freepatentsonline.com/20160086350.pdf},
  videolink = {https://youtu.be/ZKlC9PA1IDg}
}
► D. Michel, K. Papoutsakis and A.A. Argyros, "Gesture Recognition Apparatuses, Methods and Systems for Human-Machine Interaction", United States Patent No 20160078289, Filed: 16 September, 2015, Published: 17 March, 2016. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: The GESTURE RECOGNITION APPARATUSES, METHODS AND SYSTEMS FOR HUMAN-MACHINE INTERACTION (GRA) discloses vision-based gesture recognition. GRA can be implemented in any application involving tracking, detection and/or recognition of gestures or motion in general. Disclosed methods and systems consider a gestural vocabulary of a predefined number of user specified static and/or dynamic hand gestures that are mapped with a database to convey messages. In one implementation, the disclosed systems and methods support gesture recognition by detecting and tracking body parts, such as arms, hands and fingers, and by performing spatio-temporal segmentation and recognition of the set of predefined gestures, based on data acquired by an RGBD sensor. In one implementation, a model of the hand is employed to detect hand and finger candidates. At a higher level, hand posture models are defined and serve as building blocks to recognize gestures.
BibTeX:
@patent{MichelPapoutsakisArgyros2016a,
  author = {Michel, Damien and Papoutsakis, Konstantinos and Argyros, Antonis A}, 
  title = {Gesture Recognition Apparatuses, Methods and Systems for Human-Machine Interaction}, 
  nationality = {United States}, 
  number = {20160078289}, 
  year = {2016}, 
  month = {March}, 
  day = {17}, 
  yearfiled = {2015}, 
  monthfiled = {September}, 
  dayfiled = {16}, 
  url = {http://users.ics.forth.gr/ argyros/res_gesturesforHRI.html}, 
  projects =  {ROBOHOW,HOBBIT,ACANTO},
  doi = {http://www.freepatentsonline.com/y2016/0078289.html},
  pdflink = {http://www.freepatentsonline.com/20160078289.pdf},
  videolink = {https://youtu.be/eIIzgjG2V7A}
}
► D. Fischinger, P. Einramhof, K. Papoutsakis, W. Wohlkinger, P. Mayer, P. Panek, S. Hofmann, T. Koertner, A. Weiss, A.A. Argyros and others, "Hobbit, a care robot supporting independent living at home: First prototype and lessons learned", Robotics and Autonomous Systems, Elsevier, vol. 75, no. A, pp. 60-78, January 2016. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: One option to address the challenge of demographic transition is to build robots that enable aging in place. Falling has been identified as the most relevant factor to cause a move to a care facility. The Hobbit project combines research from robotics, gerontology, and human–robot interaction to develop a care robot which is capable of fall prevention and detection as well as emergency detection and handling. Moreover, to enable daily interaction with the robot, other functions are added, such as bringing objects, offering reminders, and entertainment. The interaction with the user is based on a multimodal user interface including automatic speech recognition, text-to-speech, gesture recognition, and a graphical touch-based user interface. We performed controlled laboratory user studies with a total of 49 participants (aged 70 plus) in three EU countries (Austria, Greece, and Sweden). The collected user responses on perceived usability, acceptance, and affordability of the robot demonstrate a positive reception of the robot from its target user group. This article describes the principles and system components for navigation and manipulation in domestic environments, the interaction paradigm and its implementation in a multimodal user interface, the core robot tasks, as well as the results from the user studies, which are also reflected in terms of lessons we learned and we believe are useful to fellow researchers.
BibTeX:
@article{FischingerEinramhofPapoutsakisEtAl2016a,
  author = {Fischinger, David and Einramhof, Peter and Papoutsakis, Konstantinos and Wohlkinger, Walter and Mayer, Peter and Panek, Paul and Hofmann, Stefan and Koertner, Tobias and Weiss, Astrid and Argyros, Antonis A and others},
  title = {Hobbit, a care robot supporting independent living at home: First prototype and lessons learned},
  journal = {Robotics and Autonomous Systems},
  publisher = {Elsevier},
  year = {2016},
  month = {January},
  volume = {75},
  number = {A},
  pages = {60--78},
  url = {http://users.ics.forth.gr/ argyros/res_gesturesforHRI.html},
  projects =  {HOBBIT},
  doi = {http://www.sciencedirect.com/science/article/pii/S0921889014002140},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2016_journal_RAS_HOBBIT.pdf}
}
► D. Michel, C. Panagiotakis and A.A. Argyros, "Tracking the articulated motion of the human body with two RGBD cameras", Machine Vision Applications, Springer, vol. 26, no. 1, pp. 41-54, 2015. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: We present a model-based, top-down solution to the problem of tracking the 3D position, orientation and full articulation of the human body from markerless visual observations obtained by two synchronized RGBD cameras. Inspired by recent advances to the problem of model-based hand tracking Oikonomidis et al. (Efficient Model-based 3D Tracking of Hand Articulations using Kinect, 2011), we treat human body tracking as an optimization problem that is solved using stochastic optimization techniques. We show that the proposed approach outperforms in accuracy state of the art methods that rely on a single RGBD camera. Thus, for applications that require increased accuracy and can afford the extra-complexity introduced by the second sensor, the proposed approach constitutes a viable solution to the problem of markerless human motion tracking. Our findings are supported by an extensive quantitative evaluation of the method that has been performed on a publicly available data set that is annotated with ground truth.
BibTeX:
@article{MichelPanagiotakisArgyros2015a,
  author = {Michel, Damien and Panagiotakis, Costas and Argyros, Antonis A},
  title = {Tracking the articulated motion of the human body with two RGBD cameras},
  journal = {Machine Vision Applications},
  publisher = {Springer},
  year = {2015},
  volume = {26},
  number = {1},
  pages = {41--54},
  url = {http://users.ics.forth.gr/ argyros/res_humanbody_two_kinects.html},
  projects =  {HOBBIT,ERASITECHNIS},
  doi = {10.1007/s00138-014-0651-0},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2015_journal_MVA_humanbody.pdf},
  videolink = {https://youtu.be/n5irgHVuFwc}
}
► N. Kyriazis and A.A. Argyros, "3D Tracking of Hands Interacting with Several Objects", In IEEE International Conference on Computer Vision Workshops (OUI 2015 - ICCVW 2015), IEEE, Santiago, Chile, November 2015. [BibTeX] [PDF] [URL] [VIDEO]
BibTeX:
@inproceedings{KyriazisArgyros2015a,
  author = {Kyriazis, Nikolaos and Argyros, Antonis A},
  title = {3D Tracking of Hands Interacting with Several Objects},
  booktitle = {IEEE International Conference on Computer Vision Workshops (OUI 2015 - ICCVW 2015)},
  publisher = {IEEE},
  year = {2015},
  month = {November},
  address = {Santiago, Chile},
  url = {http://cvrlcode.ics.forth.gr/handtracking/},
  projects =  {ROBOHOW,WEARHAP},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2015_12_OUI_mbv.pdf},
  videolink = {https://youtu.be/SCOtBdhDMKg}
}
► P. Panteleris, N. Kyriazis and A.A. Argyros, "Recovering 3D models of manipulated objects through 3D tracking of hand-object interaction", In IEEE International Conference on Computer Vision Workshops (OUI 2015 - ICCVW 2015), IEEE, Santiago, Chile, November 2015. [BibTeX] [PDF] [URL] [VIDEO]
BibTeX:
@inproceedings{PantelerisKyriazisArgyros2015b,
  author = {Panteleris, Paschalis and Kyriazis, Nikolaos and Argyros, Antonis A},
  title = {Recovering 3D models of manipulated objects through 3D tracking of hand-object interaction},
  booktitle = {IEEE International Conference on Computer Vision Workshops (OUI 2015 - ICCVW 2015)},
  publisher = {IEEE},
  year = {2015},
  month = {November},
  address = {Santiago, Chile},
  url = {http://users.ics.forth.gr/ argyros/res_handunknownobject.html},
  projects =  {ROBOHOW},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2015_12_OUI_padeler.pdf},
  videolink = {https://youtu.be/9r43PtJ0Fwg}
}
► T.-H. Pham, A. Kheddar, A. Qammaz and A.A. Argyros, "Capturing and Reproducing Hand-Object Interactions Through Vision-Based Force Sensing", In IEEE International Conference on Computer Vision Workshops (OUI 2015 - ICCVW 2015), IEEE, Santiago, Chile, November 2015. [BibTeX] [PDF] [URL] [VIDEO]
BibTeX:
@inproceedings{PhamKheddarQammazEtAl2015b,
  author = {Pham, Tu-Hoa and Kheddar, Abderahmanne and Qammaz, Ammar and Argyros, Antonis A},
  title = {Capturing and Reproducing Hand-Object Interactions Through Vision-Based Force Sensing},
  booktitle = {IEEE International Conference on Computer Vision Workshops (OUI 2015 - ICCVW 2015)},
  publisher = {IEEE},
  year = {2015},
  month = {November},
  address = {Santiago, Chile},
  url = {http://users.ics.forth.gr/ argyros/res_fsv.html},
  projects =  {ROBOHOW},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2015_12_OUI_FSV.pdf},
  videolink = {https://youtu.be/C4k-FPWM1t0}
}
► N. Kyriazis, I. Oikonomidis, P. Panteleris, D. Michel, A. Qammaz, A. Makris, K. Tzevanidis, P. Douvantzis, K. Roditakis and A.A. Argyros, "A Generative Approach to Tracking Hands and Their Interaction with Objects", In Man-Machine Interactions 4 - International Conference on Man-Machine Interactions (ICMMI 2015), Springer, pp. 19-28, Kocierz, Poland, October 2015. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: Markerless 3D tracking of hands in action or in interaction with objects provides rich information that can be used to interpret a number of human activities. In this paper, we review a number of relevant methods we have proposed. All of them focus on hands, objects and their interaction and follow a generative approach. The major strength of such an approach is the straightforward fashion in which arbitrarily complex priors can be easily incorporated towards solving the tracking problem and their capability to generalize to greater and/or different domains. The proposed generative approach is implemented in a single, unified computational framework.
BibTeX:
@inproceedings{KyriazisOikonomidisPantelerisEtAl2015a,
  author = {Kyriazis, Nikolaos and Oikonomidis, Iason and Panteleris, Paschalis and Michel, Damien and Qammaz, Ammar and Makris, Alexandros and Tzevanidis, Konstantinos and Douvantzis, Petros and Roditakis, Konstantinos and Argyros, Antonis A},
  title = {A Generative Approach to Tracking Hands and Their Interaction with Objects},
  booktitle = {Man-Machine Interactions 4 - International Conference on Man-Machine Interactions (ICMMI 2015)},
  publisher = {Springer},
  year = {2015},
  month = {October},
  pages = {19--28},
  address = {Kocierz, Poland},
  url = {http://cvrlcode.ics.forth.gr/handtracking/},
  projects =  {ROBOHOW,WEARHAP},
  doi = {10.1007/978-3-319-23437-3_2},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2015_10_ICMMI_keynote.pdf}
}
► K. Paliouras and A.A. Argyros, "Towards the Automatic Definition of the Objective Function for Model-Based 3D Hand Tracking", In Man-Machine Interactions 4 - International Conference on Man-Machine Interactions (ICMMI 2015), Springer, pp. 353-363, Kocierz, Poland, October 2015. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: Recently, model-based approaches have produced very promising results to the problems of 3D hand tracking. The current state of the art method recovers the 3D position, orientation and 20 DOF articulation of a human hand from markerless visual observations obtained by an RGB-D sensor. Hand pose estimation is formulated as an optimization problem, seeking for the hand model parameters that minimize an objective function that quantifies the discrepancy between the appearance of hand hypotheses and the actual hand observation. The design of such a function is a complicated process that requires a lot of prior experience with the problem. In this paper we automate the definition of the objective function in such optimization problems. First, a set of relevant, candidate image features is computed. Then, given synthetic data sets with ground truth information, regression analysis is used to combine these features in an objective function that seeks to maximize optimization performance. Extensive experiments study the performance of the proposed approach based on various dataset generation strategies and feature selection techniques.
BibTeX:
@inproceedings{PaliourasArgyros2015a,
  author = {Konstantinos Paliouras and Argyros, Antonis A},
  title = {Towards the Automatic Definition of the Objective Function for Model-Based 3D Hand Tracking},
  booktitle = {Man-Machine Interactions 4 - International Conference on Man-Machine Interactions (ICMMI 2015)},
  publisher = {Springer},
  year = {2015},
  month = {October},
  pages = {353--363},
  address = {Kocierz, Poland},
  projects =  {ROBOHOW},
  doi = {10.1007/978-3-319-23437-3_30},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2015_10_ICMMI_auto_objfun.pdf}
}
► A. Makris and A.A. Argyros, "Model-based 3D Hand Tracking with on-line Shape Adaptation", In British Machine Vision Conference (BMVC 2015), BMVA, pp. 77-1, Swansea, UK, September 2015. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: One of the shortcomings of the existing model-based 3D hand tracking methods is the fact that they consider a fixed hand model, i.e. one with fixed shape parameters. In this work we propose an online model-based method that tackles jointly the hand pose tracking and the hand shape estimation problems. The hand pose is estimated using a hierarchical particle filter. The hand shape is estimated by fitting the shape model parameters over the observations in a frame history. The candidate shapes required by the fitting framework are obtained by optimizing the shape parameters independently in each frame. Extensive experiments demonstrate that the proposed method tracks the pose of the hand and estimates its shape parameters accurately, even under heavy noise and inaccurate shape initialization.
BibTeX:
@inproceedings{MakrisArgyros2015a,
  author = {Makris, Alexandros and Argyros, Antonis A},
  title = {Model-based 3D Hand Tracking with on-line Shape Adaptation},
  booktitle = {British Machine Vision Conference (BMVC 2015)},
  publisher = {BMVA},
  year = {2015},
  month = {September},
  pages = {77--1},
  address = {Swansea, UK},
  url = {http://users.ics.forth.gr/ argyros/res_handadaptation.html},
  projects =  {ROBOHOW},
  doi = {10.5244/C.29.77},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2015_09_BMVC_adaptivehandtracking.pdf},
  videolink = {https://youtu.be/4dgwoKkDSn8}
}
► P. Panteleris, N. Kyriazis and A.A. Argyros, "3D Tracking of Human Hands in Interaction with Unknown Objects", In British Machine Vision Conference (BMVC 2015), BMVA, pp. 123-1, Swansea, UK, September 2015. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: The analysis and the understanding of object manipulation scenarios based on computer vision techniques can be greatly facilitated if we can gain access to the full articulation of the manipulating hands and the 3D pose of the manipulated objects. Currently, there exist methods for tracking hands in interaction with objects whose 3D models are known. There are also methods that can reconstruct 3D models of objects that are partially observable in each frame of a sequence. However, to the best of our knowledge, no method can track hands in interaction with unknown objects. In this paper we propose such a method. Experimental results show that hand tracking can be achieved with an accuracy that is comparable to the one obtained by methods that assume knowledge of the object models. Additionally, as a by-product, the proposed method delivers accurate 3D models of the manipulated objects.
BibTeX:
@inproceedings{PantelerisKyriazisArgyros2015a,
  author = {Panteleris, Paschalis and Kyriazis, Nikolaos and Argyros, Antonis A},
  title = {3D Tracking of Human Hands in Interaction with Unknown Objects},
  booktitle = {British Machine Vision Conference (BMVC 2015)},
  publisher = {BMVA},
  year = {2015},
  month = {September},
  pages = {123--1},
  address = {Swansea, UK},
  url = {http://users.ics.forth.gr/ argyros/res_handunknownobject.html},
  projects =  {ROBOHOW},
  doi = {10.5244/C.29.123},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2015_09_BMVC_unknownobjects.pdf},
  videolink = {https://youtu.be/9r43PtJ0Fwg}
}
► G. Poier, K. Roditakis, S. Schulter, D. Michel, H. Bischof and A.A. Argyros, "Hybrid One-Shot 3D Hand Pose Estimation by Exploiting Uncertainties", In British Machine Vision Conference (BMVC 2015), BMVA, pp. 182-1, Swansea, UK, September 2015. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: Model-based approaches to 3D hand tracking have been shown to perform well in a wide range of scenarios. However, they require initialisation and cannot recover easily from tracking failures that occur due to fast hand motions. Data-driven approaches, on the other hand, can quickly deliver a solution, but the results often suffer from lower accuracy or missing anatomical validity compared to those obtained from model-based approaches. In this work we propose a hybrid approach for hand pose estimation from a single depth image. First, a learned regressor is employed to deliver multiple initial hypotheses for the 3D position of each hand joint. Subsequently, the kinematic parameters of a 3D hand model are found by deliberately exploiting the inherent uncertainty of the inferred joint proposals. This way, the method provides anatomically valid and accurate solutions without requiring manual initialisation or suffering from track losses. Quantitative results on several standard datasets demonstrate that the proposed method
outperforms state-of-the-art representatives of the model-based, data-driven and hybrid paradigms.
BibTeX:
@inproceedings{PoierRoditakisSchulterEtAl2015a,
  author = {Poier, Georg and Roditakis, Konstantinos and Schulter, Samuel and Michel, Damien and Bischof, Horst and Argyros, Antonis A},
  title = {Hybrid One-Shot 3D Hand Pose Estimation by Exploiting Uncertainties},
  booktitle = {British Machine Vision Conference (BMVC 2015)},
  publisher = {BMVA},
  year = {2015},
  month = {September},
  pages = {182--1},
  address = {Swansea, UK},
  url = {https://lrs.icg.tugraz.at/research/hybridhape/},
  projects =  {WEARHAP},
  doi = {10.5244/C.29.182},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2015_09_BMVC_hybrid.pdf}
}
► A. Qammaz, N. Kyriazis and A.A. Argyros, "Boosting the Performance of Model-based 3D Tracking by Employing Low Level Motion Cues", In British Machine Vision Conference (BMVC 2015), BMVA, pp. 144-1, Swansea, UK, September 2015. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: 3D tracking of objects and hands in an object manipulation scenario is a very interesting computer vision problem with a wide variety of applications ranging from consumer electronics to robotics and medicine. Recent advances in this research topic allow for 3D tracking of complex scenarios involving bimanual manipulation of several rigid objects using commodity hardware and with high accuracy. The problem with these approaches is that they treat tracking as a search problem whose dimensionality increases with the number of objects in the scene. This fact typically limits the number of the tracked objects and/or the processing framerate. In this paper we present a method that utilizes simple low level motion cues for dynamically assigning computational resources to parts of the scene where they are actually required. In a series of experiments, we show that this simple idea improves tracking performance dramatically at a cost of only a minor degradation of tracking accuracy.
BibTeX:
@inproceedings{QammazKyriazisArgyros2015a,
  author = {Qammaz, Ammar and Kyriazis, Nikolaos and Argyros, Antonis A},
  title = {Boosting the Performance of Model-based 3D Tracking by Employing Low Level Motion Cues},
  booktitle = {British Machine Vision Conference (BMVC 2015)},
  publisher = {BMVA},
  year = {2015},
  month = {September},
  pages = {144--1},
  address = {Swansea, UK},
  url = {http://users.ics.forth.gr/ argyros/res_ect.html},
  projects =  {ROBOHOW,WEARHAP},
  doi = {10.5244/C.29.144},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2015_09_BMVC_fect.pdf},
  videolink = {https://youtu.be/nPru6PpWrK4}
}
► C. Hernandez-Matas, X. Zabulis and A.A. Argyros, "Retinal Image Registration Based on Keypoint Correspondences, Spherical Eye Modeling and Camera Pose Estimation", In IEEE Engineering in Medicine and Biology Conference (EMBC 2015), IEEE, pp. 5650-5654, Milan, Italy, August 2015. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: In this work, an image registration method for two retinal images is proposed. The proposed method utilizes keypoint correspondences and assumes a spherical model of the eye. Image registration is treated as a pose estimation problem, which requires estimation of the rigid transformation that relates the two images. Using this estimate, one image can be warped so that it is registered to the coordinate frame of the other. Experimental evaluation shows improved accuracy over state-of-the-art approaches as well as robustness to noise and spurious keypoint correspondences. Experiments also indicate the method's applicability to diagnostic image enhancement and comparative analysis of images from different examinations.
BibTeX:
@inproceedings{Hernandez-MatasZabulisArgyros2015a,
  author = {Hernandez-Matas, Carlos and Zabulis, Xenophon and Argyros, Antonis A},
  title = {Retinal Image Registration Based on Keypoint Correspondences, Spherical Eye Modeling and Camera Pose Estimation},
  booktitle = {IEEE Engineering in Medicine and Biology Conference (EMBC 2015)},
  publisher = {IEEE},
  year = {2015},
  month = {August},
  pages = {5650--5654},
  address = {Milan, Italy},
  projects =  {REVAMMAD},
  doi = {10.1109/EMBC.2015.7319674},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2015_09_EMBC_RetinalImageRegistration.pdf}
}
► K. Roditakis and A.A. Argyros, "Quantifying the Effect of a Colored Glove in the 3D Tracking of a Human Hand", In International Conference on Computer Vision Systems (ICVS 2015), Springer, pp. 404-414, Copenhagen, Denmark, July 2015. [Abstract] [BibTeX] [DOI] [PDF] [VIDEO]
Abstract: Research in vision-based 3D hand tracking targets primarily the scenario in which a bare hand performs unconstrained motion in front of a camera system. Nevertheless, in several important application domains, augmenting the hand with color information so as to facilitate the tracking process constitutes an acceptable alternative. With this observation in mind, in this work we propose a modification of a state of the art method [12] for markerless 3D hand tracking, that takes advantage of the richer observations resulting from a colored glove. We do so by modifying the 3D hand model employed in the aforementioned hypothesize-and-test method as well as the objective function that is minimized in its optimization step. Quantitative and qualitative results obtained from a comparative evaluation of the baseline method to the proposed approach confirm that the latter achieves a remarkable increase in tracking accuracy and robustness and, at the same time, reduces drastically the associated computational costs.
BibTeX:
@inproceedings{RoditakisArgyros2015a,
  author = {Konstantinos Roditakis and Argyros, Antonis A},
  title = {Quantifying the Effect of a Colored Glove in the 3D Tracking of a Human Hand},
  booktitle = {International Conference on Computer Vision Systems (ICVS 2015)},
  publisher = {Springer},
  year = {2015},
  month = {July},
  pages = {404--414},
  address = {Copenhagen, Denmark},
  projects =  {WEARHAP},
  doi = {10.1007/978-3-319-20904-3_36},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2015_07_ICVS_colorglove.pdf},
  videolink = {https://youtu.be/9nkHIgFYtzE}
}
► A. Makris, N. Kyriazis and A.A. Argyros, "Hierarchical particle filtering for 3d hand tracking", In IEEE Computer Vision and Pattern Recognition Workshops (HANDS 2015 - CVPRW 2015), IEEE, pp. 8-17, Boston, USA, June 2015. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: We present a fast and accurate 3D hand tracking method which relies on RGB-D data. The method follows a model based approach using a hierarchical particle filter variant to track the model's state. The filter estimates the probability density function of the state's posterior. As such, it has increased robustness to observation noise and compares favourably to existing methods that can be trapped in local minima resulting in track loses. The data likelihood term is calculated by measuring the discrepancy between the rendered 3D model and the observations. Extensive experiments with real and simulated data show that hand tracking is achieved at a frame rate of 90fps with less that 10mm average error using a GPU implementation, thus comparing favourably to the state of the art in terms of both speed and tracking accuracy.
BibTeX:
@inproceedings{MakrisKyriazisArgyros2015a,
  author = {Makris, Alexandros and Kyriazis, Nikolaos and Argyros, Antonis A},
  title = {Hierarchical particle filtering for 3d hand tracking},
  booktitle = {IEEE Computer Vision and Pattern Recognition Workshops (HANDS 2015 - CVPRW 2015)},
  publisher = {IEEE},
  year = {2015},
  month = {June},
  pages = {8--17},
  address = {Boston, USA},
  url = {http://users.ics.forth.gr/ argyros/res_hmf.html},
  projects =  {WEARHAP, ROBOHOW},
  doi = {10.1109/CVPRW.2015.7301343},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2015_06_HANDS_hmf.pdf},
  videolink = {https://youtu.be/DR8YUOAM3QM}
}
► T.-H. Pham, A. Kheddar, A. Qammaz and A.A. Argyros, "Towards force sensing from vision: Observing hand-object interactions to infer manipulation forces", In IEEE Computer Vision and Pattern Recognition (CVPR 2015), IEEE, pp. 2810-2819, Boston, USA, June 2015. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: We present a novel, non-intrusive approach for estimating contact forces during hand-object interactions relying solely on visual input provided by a single RGB-D camera. We consider a manipulated object with known geometrical and physical properties. First, we rely on model-based visual tracking to estimate the object's pose together with that of the hand manipulating it throughout the motion. Following this, we compute the object's first and second order kinematics using a new class of numerical differentiation operators. The estimated kinematics is then instantly fed into a second-order cone program that returns a minimal force distribution explaining the observed motion. However, humans typically apply more forces than mechanically required when manipulating objects. Thus, we complete our estimation method by learning these excessive forces and their distribution among the fingers in contact. We provide a full validity analysis of the proposed method by evaluating it based on ground truth data from additional sensors such as accelerometers, gyroscopes and pressure sensors. Experimental results show that force sensing from vision (FSV) is indeed feasible.
BibTeX:
@inproceedings{PhamKheddarQammazEtAl2015a,
  author = {Pham, Tu-Hoa and Kheddar, Abderrahmane and Qammaz, Ammar and Argyros, Antonis A},
  title = {Towards force sensing from vision: Observing hand-object interactions to infer manipulation forces},
  booktitle = {IEEE Computer Vision and Pattern Recognition (CVPR 2015)},
  publisher = {IEEE},
  year = {2015},
  month = {June},
  pages = {2810--2819},
  address = {Boston, USA},
  url = {http://users.ics.forth.gr/ argyros/res_fsv.html},
  projects =  {ROBOHOW},
  doi = {10.1109/CVPR.2015.7298898},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2015_06_CVPR_fsv.pdf},
  videolink = {https://youtu.be/C4k-FPWM1t0}
}
► L. Palopoli, A.A. Argyros, J. Birchbauer, A. Colombo, D. Fontanelli, A. Legay, A. Garulli, A. Giannitrapani, D. Macii, F. Moro and others, "Navigation assistance and guidance of older adults across complex public spaces: the DALi approach", Intelligent Service Robotics, Springer, vol. 8, no. 2, pp. 77-92, April 2015. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: The Devices for Assisted Living (DALi) project is a research initiative sponsored by the European Commission under the FP7 programme aiming for the development of a robotic device to assist people with cognitive impairments in navigating complex environments. The project revisits the popular paradigm of the walker enriching it with sensing abilities (to perceive the environment), with cognitive abilities (to decide the best path across the space) and with mechanical, visual, acoustic and haptic guidance devices (to guide the person along the path). In this paper, we offer an overview of the developed system and describe in detail some of its most important technological aspects.
BibTeX:
@article{PalopoliArgyrosBirchbauerEtAl2015a,
  author = {Palopoli, Luigi and Argyros, Antonis A and Birchbauer, Josef and Colombo, Alessio and Fontanelli, Daniele and Legay, Axel and Garulli, Andrea and Giannitrapani, Antonello and Macii, David and Moro, Federico and others},
  title = {Navigation assistance and guidance of older adults across complex public spaces: the DALi approach},
  journal = {Intelligent Service Robotics},
  publisher = {Springer},
  year = {2015},
  month = {April},
  volume = {8},
  number = {2},
  pages = {77--92},
  url = {http://users.ics.forth.gr/ argyros/res_slammot.html},
  projects =  {DALI},
  doi = {10.1007/s11370-015-0169-y},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2015_journal_IJSR_DALi.pdf}
}
► D. Michel, K.E. Papoutsakis and A.A. Argyros, "Gesture Recognition Supporting the Interaction of Humans with Socially Assistive Robots", In Advances in Visual Computing (ISVC 2014), Springer, pp. 793-804, Las Vegas, Nevada, USA, December 2014. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: We propose a new approach for vision-based gesture recognition to support robust and efficient human robot interaction towards developing socially assistive robots. The considered gestural vocabulary consists of five, user specified hand gestures that convey messages of fundamental importance in the context of human-robot dialogue. Despite their small number, the recognition of these gestures exhibits considerable challenges. Aiming at natural, easy-to-memorize means of interaction, users have identified gestures consisting of both static and dynamic hand configurations that involve different scales of observation (from arms to fingers) and exhibit intrinsic ambiguities. Moreover, the gestures need to be recognized regardless of the multifaceted variability of the human subjects performing them. Recognition needs to be performed online, in continuous video streams containing other irrelevant/unmodeled motions. All the above need to be achieved by analyzing information acquired by a possibly moving RGBD camera, in cluttered environments with considerable light variations. We present a gesture recognition method that addresses the above challenges, as well as promising experimental results obtained from relevant user trials.
BibTeX:
@inproceedings{MichelPapoutsakisArgyros2014a,
  author = {Michel, Damien and Konstantinos E. Papoutsakis and Argyros, Antonis A},
  title = {Gesture Recognition Supporting the Interaction of Humans with Socially Assistive Robots},
  booktitle = {Advances in Visual Computing (ISVC 2014)},
  publisher = {Springer},
  year = {2014},
  month = {December},
  pages = {793--804},
  address = {Las Vegas, Nevada, USA},
  url = {http://users.ics.forth.gr/ argyros/res_gesturesforHRI.html},
  projects =  {HOBBIT},
  doi = {10.1007/978-3-319-14249-4_76},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2014_12_ISVC_gestures.pdf},
  videolink = {https://youtu.be/eIIzgjG2V7A}
}
► D.I. Kosmopoulos, K. Papoutsakis and A.A. Argyros, "Online segmentation and classification of modeled actions performed in the context of unmodeled ones", In British Machine Vision Conference (BMVC 2014), BMVA, Nottingham, UK, September 2014. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: In this work, we provide a discriminative framework for online simultaneous segmentation and classification of visual actions, which deals effectively with unknown sequences that may interrupt the known sequential patterns. To this end we employ Hough transform to vote in a 3D space for the begin point, the end point and the label of the segmented part of the input stream. An SVM is used to model each class and to suggest putative labeled segments on the timeline. To identify the most plausible segments among the putative ones we apply a dynamic programming algorithm, which maximises an objective function for label assignment in linear time. The performance of our method is evaluated on synthetic as well as on real data (Weizmann and Berkeley multimodal human action database). The proposed approach is of comparable accuracy to the state of the art for online stream segmentation and classification and performs considerably better in the presence of previously unseen actions.
BibTeX:
@inproceedings{KosmopoulosPapoutsakisArgyros2014a,
  author = {Kosmopoulos, Dimitrios I and Papoutsakis, Konstantinos and Argyros, Antonis A},
  title = {Online segmentation and classification of modeled actions performed in the context of unmodeled ones},
  booktitle = {British Machine Vision Conference (BMVC 2014)},
  publisher = {BMVA},
  year = {2014},
  month = {September},
  address = {Nottingham, UK},
  url = {http://users.ics.forth.gr/ argyros/res_actions.html},
  projects =  {HOBBIT},
  doi = {10.5244/C.28.95},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2014_09_BMVC_actions.pdf},
  videolink = {https://youtu.be/LxIiTFDavpg}
}
► C. Panagiotakis, A.A. Argyros and D. Michel, "Temporal segmentation and seamless stitching of motion patterns for synthesizing novel animations of periodic dances", In IEEE International Conference on Pattern Recognition (ICPR 2014), IEEE, pp. 1892-1897, Stockholm, Sweden, August 2014. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: In this paper, we present an efficient algorithm for synthesizing novel, arbitrarily long animations of periodic dances. The input to the proposed method is motion capture data acquired from markeless visual observations of a human performing a periodic dance. The provided human motion capture data are temporally segmented into the constituent periodic motion patterns. These are further organized in a motion graph that also represents possible transitions among them. Finally, an efficient algorithm exploits this representation to come up with a previously unseen sequence of motion patterns that are stitched seamlessly into a novel, realistic dance animation. Several experiments have been conducted with real recordings of Greek folk dances. The obtained results are very promising and indicate the efficacy of the proposed approach, as well as its tolerance to dynamic and noisy human motion capture input.
BibTeX:
@inproceedings{PanagiotakisArgyrosMichel2014a,
  author = {Panagiotakis, Costas and Argyros, Antonis A and Michel, Damien},
  title = {Temporal segmentation and seamless stitching of motion patterns for synthesizing novel animations of periodic dances},
  booktitle = {IEEE International Conference on Pattern Recognition (ICPR 2014)},
  publisher = {IEEE},
  year = {2014},
  month = {August},
  pages = {1892--1897},
  address = {Stockholm, Sweden},
  url = {https://sites.google.com/site/costaspanagiotakis/research/dancer},
  projects =  {ERASITECHNIS,HOBBIT},
  doi = {10.1109/ICPR.2014.331},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2014_08_ICPR_danceanimation.pdf},
  videolink = {https://youtu.be/SYKjGpV_dN0}
}
► N. Kyriazis and A.A. Argyros, "Scalable 3D Tracking of Multiple Interacting Objects", In IEEE Computer Vision and Pattern Recognition (CVPR 2014), IEEE, pp. 3430-3437, Columbus, Ohio, USA, June 2014. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: We consider the problem of tracking multiple interacting objects in 3D, using RGBD input and by considering a hypothesize-and-test approach. Due to their interaction, objects to be tracked are expected to occlude each other in the field of view of the camera observing them. A naive approach would be to employ a Set of Independent Trackers (SIT) and to assign one tracker to each object. This approach scales well with the number of objects but fails as occlusions become stronger due to their disjoint consideration. The solution representing the current state of the art employs a single Joint Tracker (JT) that accounts for all objects simultaneously. This directly resolves ambiguities due to occlusions but has a computational complexity that grows geometrically with the number of tracked objects. We propose a middle ground, namely an Ensemble of Collaborative Trackers (ECT), that combines best traits from both worlds to deliver a practical and accurate solution to the multi-object 3D tracking problem. We present quantitative and qualitative experiments with several synthetic and real world sequences of diverse complexity. Experiments demonstrate that ECT manages to track far more complex scenes than JT at a computational time that is only slightly larger than that of SIT.
BibTeX:
@inproceedings{KyriazisArgyros2014a,
  author = {Kyriazis, Nikolaos and Argyros, Antonis A},
  title = {Scalable 3D Tracking of Multiple Interacting Objects},
  booktitle = {IEEE Computer Vision and Pattern Recognition (CVPR 2014)},
  publisher = {IEEE},
  year = {2014},
  month = {June},
  pages = {3430--3437},
  address = {Columbus, Ohio, USA},
  url = {http://users.ics.forth.gr/ argyros/res_ect.html},
  projects =  {ROBOHOW, WEARHAP},
  doi = {10.1109/CVPR.2014.438},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2014_06_cvpr_ect.pdf},
  videolink = {https://youtu.be/SCOtBdhDMKg}
}
► I. Oikonomidis, M.I.A. Lourakis and A.A. Argyros, "Evolutionary Quasi-random Search for Hand Articulations Tracking", In IEEE Computer Vision and Pattern Recognition (CVPR 2014), IEEE, pp. 3422-3429, Columbus, Ohio, USA, June 2014. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: We present a new method for tracking the 3D position, global orientation and full articulation of human hands. Following recent advances in model-based, hypothesize-and-test methods, the high-dimensional parameter space of hand configurations is explored with a novel evolutionary optimization technique specifically tailored to the problem. The proposed method capitalizes on the fact that samples from quasi-random sequences such as the Sobol have low discrepancy and exhibit a more uniform coverage of the sampled space compared to random samples obtained from the uniform distribution. The method has been tested for the problems of tracking the articulation of a single hand (27D parameter space) and two hands (54D space). Extensive experiments have been carried out with synthetic and real data, in comparison with state of the art methods. The quantitative evaluation shows that for cases of limited computational resources, the new approach achieves a speed-up of four (single hand tracking) and eight (two hands tracking) without compromising tracking accuracy. Interestingly, the proposed method is preferable compared to the state of the art either in the case of limited computational resources or in the case of more complex (i.e., higher dimensional) problems, thus improving the applicability of the method in a number of application domains.
BibTeX:
@inproceedings{OikonomidisLourakisArgyros2014a,
  author = {Oikonomidis, Iason and Lourakis, Manolis I A and Argyros, Antonis A},
  title = {Evolutionary Quasi-random Search for Hand Articulations Tracking},
  booktitle = {IEEE Computer Vision and Pattern Recognition (CVPR 2014)},
  publisher = {IEEE},
  year = {2014},
  month = {June},
  pages = {3422--3429},
  address = {Columbus, Ohio, USA},
  url = {http://users.ics.forth.gr/ argyros/res_sobolhandtracking.html},
  projects =  {WEARHAP, ROBOHOW},
  doi = {10.1109/CVPR.2014.437},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2014_06_cvpr_sobol.pdf},
  videolink = {https://youtu.be/3yvaFuX09xY}
}
► D. Michel, X. Zabulis and A.A. Argyros, "Shape from interaction", Machine Vision Applications, Springer, vol. 25, no. 4, pp. 1077-1087, May 2014. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: We present “shape from interaction” (SfI), an approach to the problem of acquiring 3D representations of rigid objects through observing the activity of a human who handles a tool. SfI relies on the fact that two rigid objects cannot share the same physical space. The 3D reconstruction of the unknown object is achieved by tracking the known 3D tool and by carving out the space it occupies as a function of time. Due to this indirection, SfI reconstructs rigid objects regardless of their material and appearance properties and proves particularly useful for the cases of textureless, transparent, translucent, refractive and specular objects for which there exists no practical vision-based 3D reconstruction method. Additionally, object concavities that are not directly observable can also be reconstructed. The 3D tracking of the tool is formulated as an optimization problem that is solved based on visual input acquired by a multicamera system. Experimental results from a prototype implementation of SfI support qualitatively and quantitatively the effectiveness of the proposed approach.
BibTeX:
@article{MichelZabulisArgyros2014a,
  author = {Michel, Damien and Zabulis, Xenophon and Argyros, Antonis A},
  title = {Shape from interaction},
  journal = {Machine Vision Applications},
  publisher = {Springer},
  year = {2014},
  month = {May},
  volume = {25},
  number = {4},
  pages = {1077--1087},
  url = {http://users.ics.forth.gr/ argyros/res_sfi.html},
  projects =  {ROBOHOW},
  doi = {10.1007/s00138-014-0602-9},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2014_journal_MVA_sfi.pdf},
  videolink = {https://youtu.be/uZQQkGTk6-k}
}
► P. Panteleris and A.A. Argyros, "Vision-Based SLAM and Moving Objects Tracking for the Perceptual Support of a Smart Walker Platform", In European Conference on Computer Vision Workshops (HAU3D 2014 - ECCVW 2014), Springer, pp. 407-423, Zurich, Switzerland, January 2014. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: The problems of vision-based detection and tracking of independently moving objects, localization and map construction are highly interrelated, in the sense that the solution of any of them provides valuable information to the solution of the others. In this paper, rather than trying to solve each of them in isolation, we propose a method that treats all of them simultaneously. More specifically, given visual input acquired by a moving RGBD camera, the method detects independently moving objects and tracks them in time. Additionally, the method estimates the camera (ego)motion and the motion of the tracked objects in a coordinate system that is attached to the static environment, a map of which is progressively built from scratch. The loose assumptions that the method adopts with respect to the problem parameters make it a valuable component for any robotic platform that moves in a dynamic environment and requires simultaneous tracking of moving objects, egomotion estimation and map construction. The usability of the method is further enhanced by its robustness and its low computational requirements that permit real time execution even on low-end CPUs.
BibTeX:
@inproceedings{PantelerisArgyros2014a,
  author = {Paschalis Panteleris and Argyros, Antonis A},
  title = {Vision-Based SLAM and Moving Objects Tracking for the Perceptual Support of a Smart Walker Platform},
  booktitle = {European Conference on Computer Vision Workshops (HAU3D 2014 - ECCVW 2014)},
  publisher = {Springer},
  year = {2014},
  month = {January},
  pages = {407--423},
  address = {Zurich, Switzerland},
  url = {http://users.ics.forth.gr/ argyros/res_slammot.html},
  projects =  {ACANTO},
  doi = {10.1007/978-3-319-16199-0_29},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2014_09_ACVR_slammot.pdf},
  videolink = {https://youtu.be/RnKFCypUk9U}
}
► D. Grammenos, X. Zabulis, D. Michel, P. Padeleris, T. Sarmis, G. Georgalis, P. Koutlemanis, K. Tzevanidis, A.A. Argyros, M. Sifakis and others, "A prototypical interactive exhibition for the archaeological museum of Thessaloniki", International Journal of Heritage in the Digital Era, SAGE Publications, vol. 2, no. 1, pp. 75-99, 2013. [Abstract] [BibTeX] [PDF] [URL]
Abstract: In 2010, the Institute of Computer Science of the Foundation for
Research and Technology-Hellas (ICS FORTH) and the Archaeological Museum of Thessaloniki (AMTh) collaborated towards the creation of a special exhibition of prototypical interactive systems with subjects drawn from ancient Macedonia, named “Macedonia from fragments to pixels”. The exhibition comprises seven interactive systems based on the research outcomes of ICS FORTH’s Ambient Intelligence Programme. Up to the summer of 2012, more than 165.000 people have visited it. The paper initially provides some background information, including related previous research work, and then illustrates and discusses the development process that was followed for creating the exhibition. Subsequently, the technological and interactive characteristics of the project outcomes (i.e., the interactive systems) are analysed and the complementary evaluation approaches followed are briefly described. Finally, some conclusions stemming from the project are highlighted.
BibTeX:
@article{GrammenosZabulisMichelEtAl2013a,
  author = {Grammenos, Dimitris and Zabulis, Xenophon and Michel, Damine and Padeleris, Pashalis and Sarmis, Thomas and Georgalis, Giannis and Koutlemanis, Panagiotis and Tzevanidis, Konstantinos and Argyros, Antonis A and Sifakis, M and others},
  title = {A prototypical interactive exhibition for the archaeological museum of Thessaloniki},
  journal = {International Journal of Heritage in the Digital Era},
  publisher = {SAGE Publications},
  year = {2013},
  volume = {2},
  number = {1},
  pages = {75--99},
  url = {http://users.ics.forth.gr/ argyros/res_humanpresence.html},
  projects =  {AMIPROJ},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2013_journal_JHDE_macrografia.pdf}
}
► K.E. Papoutsakis and A.A. Argyros, "Integrating tracking with fine object segmentation", Image and Vision Computing, Elsevier, vol. 31, no. 10, pp. 771-785, 2013. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: We present a novel method for on-line, joint object tracking and segmentation in a monocular video captured by a possibly moving camera. Our goal is to integrate tracking and fine segmentation of a single, previously unseen, potentially non-rigid object of unconstrained appearance, given its segmentation in the first frame of an image sequence as the only prior information. To this end, we tightly couple an existing kernel-based object tracking method with Random Walker-based image segmentation. Bayesian inference mediates between tracking and segmentation, enabling effective data fusion of pixel-wise spatial and color visual cues. The fine segmentation of an object at a certain frame provides tracking with reliable initialization for the next frame, closing the loop between the two building blocks of the proposed framework. The effectiveness of the proposed methodology is evaluated experimentally by comparing it to a large collection of state of the art tracking and video-based object segmentation methods on the basis of a data set consisting of several challenging image sequences for which ground truth data is available.
BibTeX:
@article{PapoutsakisArgyros2013a,
  author = {Papoutsakis, Konstantinos E and Argyros, Antonis A},
  title = {Integrating tracking with fine object segmentation},
  journal = {Image and Vision Computing},
  publisher = {Elsevier},
  year = {2013},
  volume = {31},
  number = {10},
  pages = {771--785},
  url = {http://users.ics.forth.gr/ argyros/res_trackingsegmentation.html},
  projects =  {ROBOHOW},
  doi = {10.1016/j.imavis.2013.07.008},
  pdflink = {http://dx.doi.org/10.1016/j.imavis.2013.07.008},
  videolink = {https://youtu.be/n_z6SY3UYB0}
}
► I. Oikonomidis, N. Kyriazis and A.A. Argyros, "Tracking the Articulated Motion of Human Hands in 3D", ERCIM News, no. 95, 2013. [BibTeX] [PDF] [URL]
BibTeX:
@periodical{OikonomidisKyriazisArgyros2013a,
  author = {Oikonomidis, Iason and Kyriazis, Nikolaos and Argyros, Antonis A},
  title = {Tracking the Articulated Motion of Human Hands in 3D},
  journal = {ERCIM News},
  year = {2013},
  number = {95},
  url = {http://cvrlcode.ics.forth.gr/handtracking/},
  projects =  {ROBOHOW,WEARHAP},
  pdflink = {http://ercim-news.ercim.eu/en95/special/tracking-the-articulated-motion-of-human-hands-in-3d}
}
► S. Escalera, J. Gonzàlez, X. Baró, M. Reyes, I. Guyon, V. Athitsos, H. Escalante, L. Sigal, A.A. Argyros, C. Sminchisescu and others, "ChaLearn multi-modal gesture recognition 2013: grand challenge and workshop summary", In ACM International Conference on Multimodal Interaction (ICMI 2013), ACM, pp. 365-368, Sydney, Australia, December 2013. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: We organized a Grand Challenge and Workshop on Multi-Modal Gesture Recognition. The MMGR Grand Challenge focused on the recognition of continuous natural gestures from multi-modal data (including RGB, Depth, user mask, Skeletal model, and audio). We made available a large labeled video database of 13,858 gestures from a lexicon of 20 Italian gesture categories recorded with a KinectTM camera. More than 54 teams participated in the challenge and a final error rate of 12% was achieved by the winner of the competition. Winners of the competition published their work in the workshop of the Challenge. The MMGR Workshop was held at ICMI conference 2013, Sidney. A total of 9 relevant papers with basis on multi-modal gesture recognition were accepted for presentation. This includes multi-modal descriptors, multi-class learning strategies for segmentation and classification in temporal data, as well as relevant applications in the field, including multi-modal Social Signal Processing and multi-modal Human Computer Interfaces. Five relevant invited speakers participated in the workshop: Profs. Leonid Signal from Disney Research, Argyros, Antonis A from FORTH, Institute of Computer Science, Cristian Sminchisescu from Lund University, Richard Bowden from University of Surrey, and Stan Sclaroff from Boston University. They summarized their research in the field and discussed past, current, and future challenges in Multi-Modal Gesture Recognition.
BibTeX:
@inproceedings{EscaleraGonzalezBaroEtAl2013a,
  author = {Escalera, Sergio and Gonzàlez, Jordi and Baró, Xavier and Reyes, Miguel and Guyon, Isabelle and Athitsos, Vassilis and Escalante, Hugo and Sigal, Leonid and Argyros, Antonis A and Sminchisescu, Cristian and others},
  title = {ChaLearn multi-modal gesture recognition 2013: grand challenge and workshop summary},
  booktitle = {ACM International Conference on Multimodal Interaction (ICMI 2013)},
  publisher = {ACM},
  year = {2013},
  month = {December},
  pages = {365--368},
  address = {Sydney, Australia},
  doi = {10.1145/2522848.2532597},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2013_12_icmi_mmgr.pdf}
}
► D. Fischinger, P. Einramhof, W. Wohlkinger, K. Papoutsakis, P. Mayer, P. Panek, T. Koertner, S. Hofmann, A.A. Argyros and M. Vincze, "Hobbit-The Mutual Care Robot", In IEEE/RSJ International Conference on Intelligent Robots and Systems Workshops (ASROB 2013 - IROSW 2013), IEEE, Tokyo, Japan, November 2013. [Abstract] [BibTeX] [PDF]
Abstract: One option to face the aging society is to build robots that help old persons to stay longer at home. We present Hobbit, a robot that attempts to let users feel safe at home by preventing and detecting falls. Falling has been identified as the highest risk for older adults of getting injured so badly that they can no longer live independently at home and have to move to a care facility. Hobbit is intended to provide high usability and acceptability for the target user group while, at the same time, needs to be affordable for private customers. The development process so far (1.5 years) included a thorough user requirement analysis, conceptual interaction design, prototyping and implementation of key behaviors, as well as extensive empirical testing with target users in the laboratory. We shortly describe the overall interdisciplinary decision-making and conceptualization of the robot and will then focus on the system itself describing the hardware, basic components, and the robot tasks. Finally, we will summarize the findings of the first empirical test with 49 users in three countries and give an outlook of how the platform will be extended in future.
BibTeX:
@inproceedings{FischingerEinramhofWohlkingerEtAl2013a,
  author = {Fischinger, Davis and Einramhof, Peter and Wohlkinger, Walter and Papoutsakis, Konstantinos and Mayer, Peter and Panek, Paul and Koertner, Tobias and Hofmann, Stefan and Argyros, Antonis A and Vincze, Markus},
  title = {Hobbit-The Mutual Care Robot},
  booktitle = {IEEE/RSJ International Conference on Intelligent Robots and Systems Workshops (ASROB 2013 - IROSW 2013)},
  publisher = {IEEE},
  year = {2013},
  month = {November},
  address = {Tokyo, Japan},
  projects =  {HOBBIT},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2013_11_asrob_hobbit.pdf}
}
► P. Padeleris, X. Zabulis and A.A. Argyros, "Multicamera tracking of multiple humans based on colored visual hulls", In IEEE Conference on Emerging Technologies & Factory Automation, (ETFA 2013), IEEE, pp. 1-8, Cagliari, Italy, September 2013. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: Detecting, localizing and tracking humans within an industrial environment are three tasks which are of central importance towards achieving automation in workplaces and intelligent environments. This is because unobtrusive, real-time and reliable person tracking provides valuable input to solving problems such as workplace surveillance and event/activity recognition and, also, contributes to safety and optimized use of resources. This paper presents a passive approach to the problem of person tracking that is based on a network of conventional color cameras. The proposed approach exhibits robustness to challenging conditions that are encountered in industrial environments due to illumination artifacts, occlusions and the highly dynamic nature of the observed scenes. The multiple views of the environment that the system employs are used to obtain a volumetric representation of the humans within it, in real-time. Although human tracking can be achieved based solely on such a volumetric representation, in demanding scenes, this information is not enough to recover from tracking failures. Thus, in this work, we collect and update a representation of the color appearance of the persons in the environment. The combination of volumetric and color information reinforces tracking robustness, even when a person is not visible by any of the cameras for extended time intervals. The proposed approach has been extensively evaluated in comparison with an existing state of the art method and pertinent results are reported.
BibTeX:
@inproceedings{PadelerisZabulisArgyros2013a,
  author = {Padeleris, Pashalis and Zabulis, Xenophon and Argyros, Antonis A},
  title = {Multicamera tracking of multiple humans based on colored visual hulls},
  booktitle = {IEEE Conference on Emerging Technologies & Factory Automation, (ETFA 2013)},
  publisher = {IEEE},
  year = {2013},
  month = {September},
  pages = {1--8},
  address = {Cagliari, Italy},
  url = {http://users.ics.forth.gr/ argyros/res_humanpresence.html},
  projects =  {DALI},
  doi = {10.1109/ETFA.2013.6647982},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2013_09_etfa_coloredhulls.pdf}
}
► P. Douvantzis, I. Oikonomidis, N. Kyriazis and A.A. Argyros, "Dimensionality Reduction for Efficient Single Frame Hand Pose Estimation", In International Conference on Computer Vision Systems (ICVS 2013), Springer, pp. 143-152, St. Petersburg, Russia, July 2013. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: Model based approaches for the recovery of the 3D position, orientation and full articulation of the human hand have a number of attractive properties. One bottleneck towards their practical exploitation is their computational cost. To a large extent, this is determined by the large dimensionality of the problem to be solved. In this work we exploit the fact that the parametric joints space representing hand configurations is highly redundant. Thus, we employ Principal Component Analysis (PCA) to learn a lower dimensional space that describes compactly and effectively the human hand articulation. The reduced dimensionality of the resulting space leads to a simpler optimization problem, so model-based approaches require less computational effort to solve it. Experiments demonstrate that the proposed approach achieves better accuracy in hand pose recovery compared to a state of the art baseline method using only 1/4 of the latter’s computational budget.
BibTeX:
@inproceedings{DouvantzisOikonomidisKyriazisEtAl2013a,
  author = {Douvantzis, Petros and Oikonomidis, Iason and Kyriazis, Nikolaos and Argyros, Antonis A},
  title = {Dimensionality Reduction for Efficient Single Frame Hand Pose Estimation},
  booktitle = {International Conference on Computer Vision Systems (ICVS 2013)},
  publisher = {Springer},
  year = {2013},
  month = {July},
  pages = {143--152},
  address = {St. Petersburg, Russia},
  projects =  {WEARHAP},
  doi = {10.1007/978-3-642-39402-7_15},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2013_07_icvs_dimreduction.pdf}
}
► P. Koutlemanis, X. Zabulis, A. Ntelidakis and A.A. Argyros, "Foreground detection with a moving rgbd camera", In Advances in Visual Computing (ISVC 2013), Springer, pp. 216-227, Rethymnon, Crete, Greece, July 2013. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: A method for foreground detection in data acquired by a moving RGBD camera is proposed. The background scene is initially in a reference model. An initial estimation of camera motion is provided by a conventional point cloud registration approach of matched keypoints between the captured scene and the reference model. This initial solution is then refined based on a top-down, model based approach that evaluates candidate camera poses in a Particle Swarm Optimization framework. To evaluate a candidate pose, the method renders color and depth images of the model according to this pose and computes a dissimilarity score of the rendered images to the currently captured ones. This score is based on the direct comparison of color, depth, and surface geometry between the acquired and rendered images, while allowing for outliers due to the potential occurrence of foreground objects, or newly imaged surfaces. Extended quantitative and qualitative experimental results confirm that the proposed method produces significantly more accurate foreground segmentation maps compared to the conventional, baseline feature-based approach.
BibTeX:
@inproceedings{KoutlemanisZabulisNtelidakisEtAl2013a,
  author = {Koutlemanis, Panayotis and Zabulis, Xenophon and Ntelidakis, Antonios and Argyros, Antonis A},
  title = {Foreground detection with a moving rgbd camera},
  booktitle = {Advances in Visual Computing (ISVC 2013)},
  publisher = {Springer},
  year = {2013},
  month = {July},
  pages = {216--227},
  address = {Rethymnon, Crete, Greece},
  projects =  {WEARHAP},
  doi = {10.1007/978-3-642-41914-0_22},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2013_07_isvc_fgbg.pdf}
}
► I. Oikonomidis, N. Kyriazis, K. Tzevanidis and A.A. Argyros, "Tracking hand articulations: Relying on 3D visual hulls versus relying on multiple 2D cues", In IEEE International Symposium on Ubiquitous Virtual Reality (ISUVR 2013), IEEE, pp. 7-10, Daejeon, South Korea, July 2013. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: We present a method for articulated hand tracking that relies on visual input acquired by a calibrated multicamera system. A state-of-the-art result on this problem has been presented in [12]. In that work, hand tracking is formulated as the minimization of an objective function that quantifies the discrepancy between a hand pose hypothesis and the observations. The objective function treats the observations from each camera view in an independent way. We follow the same general optimization framework but we choose to employ the visual hull [10] as the main observation cue, which results from the integration of information from all available views prior to optimization. We investigate the behavior of the resulting method in extensive experiments and in comparison with that of [12]. The obtained results demonstrate that for low levels of noise contamination, regardless of the number of cameras, the two methods perform comparably. The situation changes when noisy observations or as few as two cameras with short baselines are employed. In these cases, the proposed method is more accurate than that of [12]. Thus, the proposed method is preferable in real-world scenarios with noisy observations obtained from easy-to-deploy, stereo camera setups.
BibTeX:
@inproceedings{OikonomidisKyriazisTzevanidisEtAl2013a,
  author = {Oikonomidis, Iason and Kyriazis, Nikolaos and Tzevanidis, Konstantinos and Argyros, Antonis A},
  title = {Tracking hand articulations: Relying on 3D visual hulls versus relying on multiple 2D cues},
  booktitle = {IEEE International Symposium on Ubiquitous Virtual Reality (ISUVR 2013)},
  publisher = {IEEE},
  year = {2013},
  month = {July},
  pages = {7--10},
  address = {Daejeon, South Korea},
  projects =  {ROBOHOW,WEARHAP},
  doi = {10.1109/ISUVR.2013.13},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2013_07_isuvr_handvisualhull.pdf}
}
► C. Panagiotakis, A. Holzapfel, D. Michel and A.A. Argyros, "Beat Synchronous Dance Animation Based on Visual Analysis of Human Motion and Audio Analysis of Music Tempo", In Advances in Visual Computing (ISVC 2013), Springer, pp. 118-127, Rethymnon, Crete, Greece, July 2013. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: We present a framework that generates beat synchronous dance animation based on the analysis of both visual and audio data. First, the articulated motion of a dancer is captured based on markerless visual observations obtained by a multicamera system. We propose and employ a new method for the temporal segmentation of such motion data into the periods of dance. Next, we use a beat tracking algorithm to estimate the pulse related to the tempo of a piece of music. Given an input music that is of the same genre as the one corresponding to the visually observed dance, we automatically produce a beat synchronous dance animation of a virtual character. The proposed approach has been validated with extensive experiments performed on a data set containing a variety on traditional Greek/Cretan dances and the corresponding music.
BibTeX:
@inproceedings{PanagiotakisHolzapfelMichelEtAl2013a,
  author = {Panagiotakis, Costas and Holzapfel, Andre and Michel, Damien and Argyros, Antonis A},
  title = {Beat Synchronous Dance Animation Based on Visual Analysis of Human Motion and Audio Analysis of Music Tempo},
  booktitle = {Advances in Visual Computing (ISVC 2013)},
  publisher = {Springer},
  year = {2013},
  month = {July},
  pages = {118--127},
  address = {Rethymnon, Crete, Greece},
  url = {https://sites.google.com/site/costaspanagiotakis/research/dancer},
  projects =  {ERASITECHNIS},
  doi = {10.1007/978-3-642-41939-3_12},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2013_07_isvc_dancer.pdf},
  videolink = {https://youtu.be/SYKjGpV_dN0}
}
► N. Kyriazis and A.A. Argyros, "Physically Plausible 3D Scene Tracking: The Single Actor Hypothesis", In IEEE Computer Vision and Pattern Recognition (CVPR 2013), IEEE, pp. 9-16, Portland, Oregon, USA, June 2013. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: In several hand-object(s) interaction scenarios, the change in the objects' state is a direct consequence of the hand's motion. This has a straightforward representation in Newtonian dynamics. We present the first approach that exploits this observation to perform model-based 3D tracking of a table-top scene comprising passive objects and an active hand. Our forward modelling of 3D hand-object(s) interaction regards both the appearance and the physical state of the scene and is parameterized over the hand motion (26 DoFs) between two successive instants in time. We demonstrate that our approach manages to track the 3D pose of all objects and the 3D pose and articulation of the hand by only searching for the parameters of the hand motion. In the proposed framework, covert scene state is inferred by connecting it to the overt state, through the incorporation of physics. Thus, our tracking approach treats a variety of challenging observability issues in a principled manner, without the need to resort to heuristics.
BibTeX:
@inproceedings{KyriazisArgyros2013a,
  author = {Kyriazis, Nikolaos and Argyros, Antonis A},
  title = {Physically Plausible 3D Scene Tracking: The Single Actor Hypothesis},
  booktitle = {IEEE Computer Vision and Pattern Recognition (CVPR 2013)},
  publisher = {IEEE},
  year = {2013},
  month = {June},
  pages = {9--16},
  address = {Portland, Oregon, USA},
  url = {http://users.ics.forth.gr/ argyros/res_singleactorhypothesis.html},
  projects =  {ROBOHOW},
  doi = {10.1109/CVPR.2013.9},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2013_06_cvpr_singleactor.pdf},
  videolink = {https://youtu.be/0RCsQPXeHRQ}
}
► K. Papoutsakis, P. Padeleris, A. Ntelidakis, S. Stefanou, X. Zabulis, D. Kosmopoulos and A.A. Argyros, "Developing visual competencies for socially assistive robots: the HOBBIT approach", In International Conference on Pervasive Technologies Related to Assistive Environments (PETRA 2013), ACM, pp. 1-7, Rhodes, Greece, May 2013. [Abstract] [BibTeX] [DOI] [PDF] [VIDEO]
Abstract: In this paper, we present our approach towards developing visual competencies for socially assistive robots within the framework of the HOBBIT project. We show how we integrated several vision modules using a layered architectural scheme. Our goal is to endow the mobile robot with visual perception capabilities so that it can interact with the users. We present the key modules of independent motion detection, object detection, body localization, person tracking, head pose estimation and action recognition and we explain how they serve the goal of natural integration of robots in social environments.
BibTeX:
@inproceedings{PapoutsakisPadelerisNtelidakisEtAl2013a,
  author = {Papoutsakis, Konstantinos and Padeleris, Pashalis and Ntelidakis, Antonis and Stefanou, Stefanos and Zabulis, Xenophon and Kosmopoulos, Dimitrios and Argyros, Antonis A},
  title = {Developing visual competencies for socially assistive robots: the HOBBIT approach},
  booktitle = {International Conference on Pervasive Technologies Related to Assistive Environments (PETRA 2013)},
  publisher = {ACM},
  year = {2013},
  month = {May},
  pages = {1--7},
  address = {Rhodes, Greece},
  projects =  {HOBBIT, DALI},
  doi = {10.1145/2504335.2504395},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2013_05_petra_hobbit.pdf},
  videolink = {https://youtu.be/LxIiTFDavpg}
}
► M. Patel, C.H. Ek, N. Kyriazis, A.A. Argyros, J.V. Miró and D. Kragic, "Language for learning complex human-object interactions", In IEEE International Conference on Robotics and Automation (ICRA 2013), IEEE, pp. 4997-5002, Karlsruhe, Germany, May 2013. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: In this paper we use a Hierarchical Hidden Markov Model (HHMM) to represent and learn complex activities/task performed by humans/robots in everyday life. Action primitives are used as a grammar to represent complex human behaviour and learn the interactions and behaviour of human/robots with different objects. The main contribution is the use of a probabilistic model capable of representing behaviours at multiple levels of abstraction to support the proposed hypothesis. The hierarchical nature of the model allows decomposition of the complex task into simple action primitives. The framework is evaluated with data collected for tasks of everyday importance performed by a human user.
BibTeX:
@inproceedings{PatelEkKyriazisEtAl2013a,
  author = {Patel, Mitesh and Ek, Carl Henrik and Kyriazis, Nikolaos and Argyros, Antonis A and Miró, Jaime Valls and Kragic, Danica},
  title = {Language for learning complex human-object interactions},
  booktitle = {IEEE International Conference on Robotics and Automation (ICRA 2013)},
  publisher = {IEEE},
  year = {2013},
  month = {May},
  pages = {4997--5002},
  address = {Karlsruhe, Germany},
  projects =  {ROBOHOW, GRASP},
  doi = {10.1109/ICRA.2013.6631291},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2013_05_icra_mitesh.pdf}
}
► D. Song, N. Kyriazis, I. Oikonomidis, C. Papazov, A.A. Argyros, D. Burschka and D. Kragic, "Predicting human intention in visual observations of hand/object interactions", In IEEE International Conference on Robotics and Automation (ICRA 2013), IEEE, pp. 1608-1615, Karlsruhe, Germany, May 2013. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: The main contribution of this paper is a probabilistic method for predicting human manipulation intention from image sequences of human-object interaction. Predicting intention amounts to inferring the imminent manipulation task when human hand is observed to have stably grasped the object. Inference is performed by means of a probabilistic graphical model that encodes object grasping tasks over the 3D state of the observed scene. The 3D state is extracted from RGB-D image sequences by a novel vision-based, markerless hand-object 3D tracking framework. To deal with the high-dimensional state-space and mixed data types (discrete and continuous) involved in grasping tasks, we introduce a generative vector quantization method using mixture models and self-organizing maps. This yields a compact model for encoding of grasping actions, able of handling uncertain and partial sensory data. Experimentation showed that the model trained on simulated data can provide a potent basis for accurate goal-inference with partial and noisy observations of actual real-world demonstrations. We also show a grasp selection process, guided by the inferred human intention, to illustrate the use of the system for goal-directed grasp imitation.
BibTeX:
@inproceedings{SongKyriazisOikonomidisEtAl2013a,
  author = {Song, Dan and Kyriazis, Nikolaos and Oikonomidis, Iason and Chavdar Papazov and Argyros, Antonis A and Burschka, Darius and Kragic, Danica},
  title = {Predicting human intention in visual observations of hand/object interactions},
  booktitle = {IEEE International Conference on Robotics and Automation (ICRA 2013)},
  publisher = {IEEE},
  year = {2013},
  month = {May},
  pages = {1608--1615},
  address = {Karlsruhe, Germany},
  projects =  {GRASP},
  doi = {10.1109/ICRA.2013.6630785},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2013_05_icra_song.pdf}
}
► X. Zabulis, D. Grammenos, T. Sarmis, K. Tzevanidis, P. Padeleris, P. Koutlemanis and A.A. Argyros, "Multicamera human detection and tracking supporting natural interaction with large-scale displays", Machine Vision Applications, Springer, vol. 24, no. 2, pp. 319-336, February 2013. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: This paper presents a computer vision system that supports non-instrumented, location-based interaction of multiple users with digital representations of large-scale artifacts. The proposed system is based on a camera network that observes multiple humans in front of a very large display. The acquired views are used to volumetrically reconstruct and track the humans robustly and in real time, even in crowded scenes and challenging human configurations. Given the frequent and accurate monitoring of humans in space and time, a dynamic and personalized textual/graphical annotation of the display can be achieved based on the location and the walk-through trajectory of each visitor. The proposed system has been successfully deployed in an archaeological museum, offering its visitors the capability to interact with and explore a digital representation of an ancient wall painting. This installation permits an extensive evaluation of the proposed system in terms of tracking robustness, computational performance and usability. Furthermore, it proves that computer vision technology can be effectively used to support non-instrumented interaction of humans with their environments in realistic settings.
BibTeX:
@article{ZabulisGrammenosSarmisEtAl2013a,
  author = {Zabulis, Xenophon and Grammenos, Dimitris and Sarmis, Thomas and Tzevanidis, Konstantinos and Padeleris, Pashalis and Koutlemanis, Panagiotis and Argyros, Antonis A},
  title = {Multicamera human detection and tracking supporting natural interaction with large-scale displays},
  journal = {Machine Vision Applications},
  publisher = {Springer},
  year = {2013},
  month = {February},
  volume = {24},
  number = {2},
  pages = {319--336},
  url = {http://users.ics.forth.gr/ argyros/res_humanpresence.html},
  projects =  {AMIPROJ,GRASP},
  doi = {10.1007/s00138-012-0408-6},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2012_XX_journal_mva_macrografia.pdf},
  videolink = {https://youtu.be/x9KTfZafZBA}
}
► D. Grammenos, X. Zabulis, D. Michel, P. Padeleris, T. Sarmis, G. Georgalis, P. Koutlemanis, K. Tzevanidis, A.A. Argyros, M. Sifakis, P. Adam-Veleni and C. Stephanidis, "Macedonia from Fragments to Pixels: A Permanent Exhibition of Interactive Systems at the Archaeological Museum of Thessaloniki", In International Conference on Progress in Cultural Heritage Preservation (EuroMed 2012), Springer, pp. 602-609, Lemesos, Cyprus, October 2012. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: The theme of this paper is an exhibition of prototypical interactive systems with subjects drawn from ancient Macedonia, named "Macedonia from fragments to pixels". Since 2010, the exhibition is hosted by the Archaeological Museum of Thessaloniki and is open daily to the general public. Up to now, more than 165.000 people have visited it. The exhibition comprises 7 interactive systems which are based on some research outcomes of the Ambient Intelligence Programme of the Institute of Computer Science, Foundation for Research and Technology - Hellas. The digital content of these systems includes objects from the Museum’s permanent collection and from Macedonia.
BibTeX:
@inproceedings{GrammenosZabulisMichelEtAl2012a,
  author = {Grammenos, Dimitris and Zabulis, Xenophon and Michel, Damien and Padeleris, Pashalis and Sarmis, Thomas and Georgalis, Giannis and Koutlemanis, Panayotis and Tzevanidis, Konstantinos and Argyros, Antonis A and Michalis Sifakis and Polyxeni Adam-Veleni and Stephanidis, Constantine},
  title = {Macedonia from Fragments to Pixels: A Permanent Exhibition of Interactive Systems at the Archaeological Museum of Thessaloniki},
  booktitle = {International Conference on Progress in Cultural Heritage Preservation (EuroMed 2012)},
  publisher = {Springer},
  year = {2012},
  month = {October},
  pages = {602--609},
  address = {Lemesos, Cyprus},
  url = {http://users.ics.forth.gr/ argyros/res_humanpresence.html},
  projects =  {AMIPROJ},
  doi = {10.1007/978-3-642-34234-9_62},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2012_10_euromed_ami.pdf}
}
► S. Stefanou and A.A. Argyros, "Efficient Scale and Rotation Invariant Object Detection Based on HOGs and Evolutionary Optimization Techniques", In Advances in Visual Computing (ISVC 2012), Springer, pp. 220-229, Rethymnon, Crete, Greece, July 2012. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: Object detection and localization in an image can be achieved by representing an object as a Histogram of Oriented Gradients (HOG). HOGs have proven to be robust object descriptors. However, to achieve accurate object localization, one must take a sliding window approach and evaluate the similarity of the descriptor over all possible windows in an image. In case that search should also be scale and rotation invariant, the exhaustive consideration of all possible HOG transformations makes the method impractical due to its computational complexity. In this work, we first propose a variant of an existing rotation invariant HOG-like descriptor. We then formulate object detection and localization as an optimization problem that is solved using the Particle Swarm Optimization (PSO) method. A series of experiments demonstrates that the proposed approach results in very large performance gains without sacrificing object detection and localization accuracy.
BibTeX:
@inproceedings{StefanouArgyros2012a,
  author = {Stefanou, Stefanos and Argyros, Antonis A},
  title = {Efficient Scale and Rotation Invariant Object Detection Based on HOGs and Evolutionary Optimization Techniques},
  booktitle = {Advances in Visual Computing (ISVC 2012)},
  publisher = {Springer},
  year = {2012},
  month = {July},
  pages = {220--229},
  address = {Rethymnon, Crete, Greece},
  projects =  {HOBBIT},
  doi = {10.1007/978-3-642-33179-4_22},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2012_07_isvc_hogpso.pdf}
}
► I. Oikonomidis, N. Kyriazis and A.A. Argyros, "Tracking the articulated motion of two strongly interacting hands", In IEEE Computer Vision and Pattern Recognition (CVPR 2012), IEEE, pp. 1862-1869, Providence, Rhode Island, USA, June 2012. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: We propose a method that relies on markerless visual observations to track the full articulation of two hands that interact with each-other in a complex, unconstrained manner. We formulate this as an optimization problem whose 54-dimensional parameter space represents all possible configurations of two hands, each represented as a kinematic structure with 26 Degrees of Freedom (DoFs). To solve this problem, we employ Particle Swarm Optimization (PSO), an evolutionary, stochastic optimization method with the objective of finding the two-hands configuration that best explains observations provided by an RGB-D sensor. To the best of our knowledge, the proposed method is the first to attempt and achieve the articulated motion tracking of two strongly interacting hands. Extensive quantitative and qualitative experiments with simulated and real world image sequences demonstrate that an accurate and efficient solution of this problem is indeed feasible.
BibTeX:
@inproceedings{OikonomidisKyriazisArgyros2012a,
  author = {Oikonomidis, Iason and Kyriazis, Nikolaos and Argyros, Antonis A},
  title = {Tracking the articulated motion of two strongly interacting hands},
  booktitle = {IEEE Computer Vision and Pattern Recognition (CVPR 2012)},
  publisher = {IEEE},
  year = {2012},
  month = {June},
  pages = {1862--1869},
  address = {Providence, Rhode Island, USA},
  url = {http://users.ics.forth.gr/ argyros/res_twohands.html},
  projects =  {GRASP,ROBOHOW},
  doi = {10.1109/CVPR.2012.6247885},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2012_06_cvpr_twohands.pdf},
  videolink = {https://youtu.be/e3G9soCdIbc}
}
► P. Padeleris, X. Zabulis and A.A. Argyros, "Head pose estimation on depth data based on Particle Swarm Optimization", In IEEE Computer Vision and Pattern Recognition Workshops (CVPRW 2012), IEEE, pp. 42-49, Providence, Rhode Island, USA, June 2012. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: We propose a method for human head pose estimation based on images acquired by a depth camera. During an initialization phase, a reference depth image of a human subject is obtained. At run time, the method searches the 6-dimensional pose space to find a pose from which the head appears identical to the reference view. This search is formulated as an optimization problem whose objective function quantifies the discrepancy of the depth measurements between the hypothesized views to the reference view. The method is demonstrated in several data sets including ones with known ground truth and comparatively evaluated with respect to state of the art methods. The obtained experimental results show that the proposed method outperforms existing methods in accuracy and tolerance to occlusions. Additionally, compared to the state of the art, it handles head pose estimation in a wider range of head poses.
BibTeX:
@inproceedings{PadelerisZabulisArgyros2012a,
  author = {Padeleris, Pashalis and Zabulis, Xenophon and Argyros, Antonis A},
  title = {Head pose estimation on depth data based on Particle Swarm Optimization},
  booktitle = {IEEE Computer Vision and Pattern Recognition Workshops (CVPRW 2012)},
  publisher = {IEEE},
  year = {2012},
  month = {June},
  pages = {42--49},
  address = {Providence, Rhode Island, USA},
  url = {http://users.ics.forth.gr/ argyros/res_rgbdheadpose.html},
  projects =  {DALI,HOBBIT,AMIPROJ},
  doi = {10.1109/CVPRW.2012.6239236},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2012_06_hau3d_headpose.pdf},
  videolink = {https://youtu.be/BFxzyagDF9A}
}
► N. Kyriazis, I. Oikonomidis and A.A. Argyros, "A GPU-powered Computational Framework for Efficient 3D Model-based Vision", In International Conference on Cognitive Systems (COGSYS 2012), Vienna, Austria, February 2012. [BibTeX] [PDF] [URL]
BibTeX:
@inproceedings{KyriazisOikonomidisArgyros2012a,
  author = {Kyriazis, Nikolaos and Oikonomidis, Iason and Argyros, Antonis A},
  title = {A GPU-powered Computational Framework for Efficient 3D Model-based Vision},
  booktitle = {International Conference on Cognitive Systems (COGSYS 2012)},
  year = {2012},
  month = {February},
  address = {Vienna, Austria},
  url = {http://cvrlcode.ics.forth.gr/handtracking/},
  projects =  {GRASP},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2012_02_cogsys_kyriazis.pdf}
}
► I. Oikonomidis, N. Kyriazis and A.A. Argyros, "Efficient Model-based Tracking of the Articulated Motion of Hands", In International Conference on Cognitive Systems (COGSYS 2012), Vienna, Austria, February 2012. [BibTeX] [PDF] [URL]
BibTeX:
@inproceedings{OikonomidisKyriazisArgyros2012b,
  author = {Oikonomidis, Iason and Kyriazis, Nikolaos and Argyros, Antonis A},
  title = {Efficient Model-based Tracking of the Articulated Motion of Hands},
  booktitle = {International Conference on Cognitive Systems (COGSYS 2012)},
  year = {2012},
  month = {February},
  address = {Vienna, Austria},
  url = {http://cvrlcode.ics.forth.gr/handtracking/},
  projects =  {GRASP},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2012_02_cogsys_oikonom.pdf}
}
► D. Michel, I. Oikonomidis and A.A. Argyros, "Scale invariant and deformation tolerant partial shape matching", Image and Vision Computing, Elsevier, vol. 29, no. 7, pp. 459-469, 2011. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: We present a novel approach to the problem of establishing the best match between an open contour and a part of a closed contour. At the heart of the proposed scheme lies a novel shape descriptor that also permits the quantification of local scale. Shape descriptors are computed along open or closed contours in a spatially non-uniform manner. The resulting ordered collections of shape descriptors constitute the global shape representation. A variant of an existing Dynamic Time Warping (DTW) matching technique is proposed to handle the matching of shape representations. Due to the properties of the employed shape descriptor, sampling scheme and matching procedure, the proposed approach performs partial shape matching that is invariant to Euclidean transformations, starting point as well as to considerable shape deformations. Additionally, the problem of matching closed-to-closed contours is naturally treated as a special case. Extensive experiments on benchmark datasets but also in the context of specific applications, demonstrate that the proposed scheme outperforms existing methods for the problem of partial shape matching and performs comparably to methods for full shape matching.
BibTeX:
@article{MichelOikonomidisArgyros2011a,
  author = {Michel, Damien and Oikonomidis, Iason and Argyros, Antonis A},
  title = {Scale invariant and deformation tolerant partial shape matching},
  journal = {Image and Vision Computing},
  publisher = {Elsevier},
  year = {2011},
  volume = {29},
  number = {7},
  pages = {459--469},
  url = {http://users.ics.forth.gr/ argyros/res_partialshapematching.html},
  projects =  {GRASP},
  doi = {10.1016/j.imavis.2011.01.008},
  pdflink = {http://dx.doi.org/10.1016/j.imavis.2011.01.008},
  videolink = {https://youtu.be/_N41CP0f0Mg}
}
► K. Tzevanidis and A.A. Argyros, "Unsupervised learning of background modeling parameters in multicamera systems", Computer Vision and Image Understanding, Academic Press, vol. 115, no. 1, pp. 105-116, 2011. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: Background modeling algorithms are commonly used in camera setups for foreground object detection. Typically, these algorithms need adjustment of their parameters towards achieving optimal performance in different scenarios and/or lighting conditions. This is a tedious process requiring considerable effort by expert users. In this work we propose a novel, fully automatic method for the tuning of foreground detection parameters in calibrated multicamera systems. The proposed method requires neither user intervention nor ground truth data. Given a set of such parameters, we define a fitness function based on the consensus built from the multicamera setup regarding whether points belong to the scene foreground or background. The maximization of this fitness function through Particle Swarm Optimization leads to the adjustment of the foreground detection parameters. Extensive experimental results confirm the effectiveness of the adopted approach.
BibTeX:
@article{TzevanidisArgyros2011a,
  author = {Tzevanidis, Konstantinos and Argyros, Antonis A},
  title = {Unsupervised learning of background modeling parameters in multicamera systems},
  journal = {Computer Vision and Image Understanding},
  publisher = {Academic Press},
  year = {2011},
  volume = {115},
  number = {1},
  pages = {105--116},
  doi = {10.1016/j.cviu.2010.09.003},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2011_01_journal_cviu_background.pdf}
}
► N. Kyriazis, I. Oikonomidis and A.A. Argyros, "Binding Computer Vision to Physics Based Simulation: The Case Study of a Bouncing Ball", In British Machine Vision Conference (BMVC 2011), BMVA, pp. 1-11, Dundee, UK, 2011. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: A dynamic scene and, therefore, its visual observations are invariably determined by the laws of physics. We demonstrate an illustrative case where physical explanation, as a vision prior, is not a commodity but a necessity. By considering the problem of ball motion estimation we show how physics-based simulation in conjunction with visual processes can lead to the reduction of the visual input required to infer physical attributes of the observed world. Even further, we show that the proposed methodology manages to reveal certain physical attributes of the observed scene that are difficult or even impossible to extract by other means. A series of experiments on synthetic data as well as experiments with image sequences of an actual ball, support the validity of the proposed approach. The use of generic tools and the top-down nature of the proposed approach make it general enough to be a likely candidate for handling even more complex problems in larger contexts.
BibTeX:
@inproceedings{KyriazisOikonomidisArgyros2011a,
  author = {Kyriazis, Nikolaos and Oikonomidis, Iason and Argyros, Antonis A},
  title = {Binding Computer Vision to Physics Based Simulation: The Case Study of a Bouncing Ball},
  booktitle = {British Machine Vision Conference (BMVC 2011)},
  publisher = {BMVA},
  year = {2011},
  pages = {1--11},
  address = {Dundee, UK},
  url = {http://users.ics.forth.gr/ argyros/res_bouncingball.html},
  projects =  {GRASP},
  doi = {10.5244/C.25.43},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2011_09_bmvc_bouncing_ball.pdf},
  videolink = {https://youtu.be/Lr5wq5It4io}
}
► I. Oikonomidis, N. Kyriazis and A.A. Argyros, "Efficient model-based 3D tracking of hand articulations using Kinect", In British Machine Vision Conference (BMVC 2011), BMVA, pp. 1-11, Dundee, UK, 2011. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: We present a novel solution to the problem of recovering and tracking the 3D position, orientation and full articulation of a human hand from markerless visual observations obtained by a Kinect sensor. We treat this as an optimization problem, seeking for the hand model parameters that minimize the discrepancy between the appearance and 3D structure of hypothesized instances of a hand model and actual hand observations. This optimization problem is effectively solved using a variant of Particle Swarm Optimization (PSO). The proposed method does not require special markers and/or a complex image acquisition setup. Being model based, it provides continuous solutions to the problem of tracking hand articulations. Extensive experiments with a prototype GPU-based implementation of the proposed method demonstrate that accurate and robust 3D tracking of hand articulations can be achieved in near real-time (15Hz).
BibTeX:
@inproceedings{OikonomidisKyriazisArgyros2011b,
  author = {Oikonomidis, Iason and Kyriazis, Nikolaos and Argyros, Antonis A},
  title = {Efficient model-based 3D tracking of hand articulations using Kinect},
  booktitle = {British Machine Vision Conference (BMVC 2011)},
  publisher = {BMVA},
  year = {2011},
  volume = {1},
  number = {2},
  pages = {1--11},
  address = {Dundee, UK},
  url = {http://cvrlcode.ics.forth.gr/handtracking/},
  projects =  {GRASP},
  doi = {10.5244/C.25.101},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2011_09_bmvc_kinect_hand_tracking.pdf},
  videolink = {https://youtu.be/Fxa43qcm1C4}
}
► R. Dillmann, T. Asfour and A.A. Argyros, "Intelligent and Cognitive Systems-Introduction to the Special Theme", ERCIM News, no. 84, pp. 12-13, 2011. [BibTeX] [PDF] [URL]
BibTeX:
@periodical{DillmannAsfourArgyros2011a,
  author = {Dillmann, Rudiger and Asfour, Tamim and Argyros, Antonis A},
  title = {Intelligent and Cognitive Systems-Introduction to the Special Theme},
  journal = {ERCIM News},
  year = {2011},
  number = {84},
  pages = {12--13},
  url = {http://users.ics.forth.gr/ argyros},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2011_01_ercimnews_cognitive_systems.pdf}
}
► X. Zabulis, D. Grammenos, A.A. Argyros, M. Sifakis and C. Stephanidis, "Macedonia: From Fragments to Pixels", ERCIM News, no. 86, 2011. [BibTeX] [PDF] [URL]
BibTeX:
@periodical{ZabulisGrammenosArgyrosEtAl2011a,
  author = {Zabulis, Xenophon and Grammenos, Dimitris and Argyros, Antonis A and Sifakis, Michalis and Stephanidis, Constantine},
  title = {Macedonia: From Fragments to Pixels},
  journal = {ERCIM News},
  year = {2011},
  number = {86},
  url = {http://users.ics.forth.gr/ argyros/res_humanpresence.html},
  projects =  {AMIPROJ},
  pdflink = {http://ercim-news.ercim.eu/en86/special/macedonia-from-fragments-to-pixels}
}
► N. Kyriazis, I. Oikonomidis and A.A. Argyros, "A GPU-powered computational framework for efficient 3D model-based vision", FORTH-ICS, TR-420, 2011. [Abstract] [BibTeX] [PDF] [URL]
Abstract: We present a generic computational framework that exploits GPU processing to cope with the significant computational requirements of a class of model-based vision problems. We study the structure of this class of problems and map the involved processes to contemporary GPU architectures. The proposed framework has been validated through its application to various instances of the problem of model-based 3D hand tracking. We show that through the exploitation of this framework near real-time performance is achieved in problems that are prohibitively expensive to solve on CPU-only architectures. Additional experiments performed in various GPU architectures demonstrate the scalability of the approach and the distribution of the execution time among the involved processes.
BibTeX:
@techreport{KyriazisOikonomidisArgyros2011b,
  author = {Kyriazis, Nikolaos and Oikonomidis, Iason and Argyros, Antonis A},
  title = {A GPU-powered computational framework for efficient 3D model-based vision},
  school = {FORTH-ICS},
  year = {2011},
  number = {TR-420},
  url = {http://cvrlcode.ics.forth.gr/handtracking/},
  projects =  {GRASP},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2011_07_tr420_gpuarch.pdf}
}
► I. Oikonomidis, N. Kyriazis and A.A. Argyros, "Full DOF tracking of a hand interacting with an object by modeling occlusions and physical constraints", In IEEE International Conference on Computer Vision (ICCV 2011), IEEE, pp. 2088-2095, Barcelona, Spain, November 2011. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: Due to occlusions, the estimation of the full pose of a human hand interacting with an object is much more challenging than pose recovery of a hand observed in isolation. In this work we formulate an optimization problem whose solution is the 26-DOF hand pose together with the pose and model parameters of the manipulated object. Optimization seeks for the joint hand-object model that (a) best explains the incompleteness of observations resulting from occlusions due to hand-object interaction and (b) is physically plausible in the sense that the hand does not share the same physical space with the object. The proposed method is the first that solves efficiently the continuous, full-DOF, joint hand-object tracking problem based solely on markerless multicamera input. Additionally, it is the first to demonstrate how hand-object interaction can be exploited as a context that facilitates hand pose estimation, instead of being considered as a complicating factor. Extensive quantitative and qualitative experiments with simulated and real world image sequences as well as a comparative evaluation with a state-of-the-art method for pose estimation of isolated hands, support the above findings.
BibTeX:
@inproceedings{OikonomidisKyriazisArgyros2011a,
  author = {Oikonomidis, Iason and Kyriazis, Nikolaos and Argyros, Antonis A},
  title = {Full DOF tracking of a hand interacting with an object by modeling occlusions and physical constraints},
  booktitle = {IEEE International Conference on Computer Vision (ICCV 2011)},
  publisher = {IEEE},
  year = {2011},
  month = {November},
  pages = {2088--2095},
  address = {Barcelona, Spain},
  url = {http://users.ics.forth.gr/ argyros/res_hope.html},
  projects =  {GRASP},
  doi = {10.1109/ICCV.2011.6126483},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2011_11_iccv_hope.pdf},
  videolink = {https://youtu.be/N3ffgj1bBGw}
}
► D. Grammenos, X. Zabulis, D. Michel, T. Sarmis, G. Georgalis, K. Tzevanidis, A.A. Argyros and C. Stephanidis, "Design and Development of Four Prototype Interactive Edutainment Exhibits for Museums", In Universal Access in Human-Computer Interaction Context Diversity UAHCI 2011, Held as Part of HCI International 2011, pp. 173-182, Orlando, Florida, USA, July 2011. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: This paper describes the outcomes stemming from the work of a multidisciplinary R&D project of ICS FORTH, aiming to explore and experiment with novel interactive museum exhibits, and to assess their utility, usability and potential impact. More specifically, four interactive systems are presented in this paper which have been integrated, tested and evaluated in a dedicated, appropriately designed, laboratory space. The paper also discusses key issues stemming from experience and observations in the course of qualitative evaluation sessions with a large number of participants.
BibTeX:
@inproceedings{GrammenosZabulisMichelEtAl2011a,
  author = {Grammenos, Dimitris and Zabulis, Xenophon and Michel, Damien and Sarmis, Thomas and Georgalis, Giannis and Tzevanidis, Konstantinos and Argyros, Antonis A and Stephanidis, Constantine},
  title = {Design and Development of Four Prototype Interactive Edutainment Exhibits for Museums},
  booktitle = {Universal Access in Human-Computer Interaction Context Diversity UAHCI 2011, Held as Part of HCI International 2011},
  year = {2011},
  month = {July},
  pages = {173--182},
  address = {Orlando, Florida, USA},
  url = {http://users.ics.forth.gr/ argyros/res_humanpresence.html},
  projects =  {AMIPROJ},
  doi = {10.1007/978-3-642-21666-4_20},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2011_07_hcii_ami.pdf}
}
► D. Grammenos, X. Zabulis, D. Michel and A.A. Argyros, "Augmented Reality Interactive Exhibits in Cartographic Heritage: An implemented case-study open to the general public", International web journal on sciences and technologies affined to history of cartography and maps, ePerimetron, vol. 6, no. 2, pp. 57-67, April 2011. [Abstract] [BibTeX] [PDF] [URL]
Abstract: This paper presents the application of the PaperView system in the domain of cartographic heritage. PaperView is a multi-user augmented-reality system for supplementing physical surfaces with digital information, through the use of pieces of plain paper that act as personal, location-aware, interactive screens. By applying the proposed method of reality augmentation in the cartographic heritage domain, the system provides the capability of retrieving multimedia information about areas of interest, overlaying information on a 2D or 3D (i.e., scale model) map, as well as comparing different versions of a single map. The technologies employed are presented, along with the interactive behavior of the system, which was instantiated and tested in three setups: (i) a map of Macedonia, Greece, including ancient Greek cities with archeological interest; (ii) a glass case containing a scale model and (iii) a part of Rigas Velestinlis’ Charta. The first two systems are currently installed and available to the general public at the Archaeological Museum of Thessaloniki, Greece, as part of a permanent exhibition of interactive systems.
BibTeX:
@article{GrammenosZabulisMichelEtAl2011b,
  author = {Grammenos, Dimitris and Zabulis, Xenophon and Michel, Damien and Argyros, Antonis A},
  title = {Augmented Reality Interactive Exhibits in Cartographic Heritage: An implemented case-study open to the general public},
  journal = {International web journal on sciences and technologies affined to history of cartography and maps},
  publisher = {ePerimetron},
  year = {2011},
  month = {April},
  volume = {6},
  number = {2},
  pages = {57--67},
  address = {Hague, Netherlands},
  url = {http://users.ics.forth.gr/ argyros/res_humanpresence.html},
  projects =  {AMIPROJ},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2011_04_ica_cartographic.pdf}
}
► D. Grammenos, D. Michel, X. Zabulis and A.A. Argyros, "PaperView: augmenting physical surfaces with location-aware digital information", In ACM Tangible, Embedded, and Embodied Interaction (TEI 2011), ACM, pp. 57-60, Funchal, Portugal, January 2011. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: A frequent need of museums is to provide visitors with context-sensitive information about exhibits in the form of maps, or scale models. This paper suggests an augmented-reality approach for supplementing physical surfaces with digital information, through the use of pieces of plain paper that act as personal, location-aware, interactive screens. The technologies employed are presented, along with the interactive behavior of the system, which was instantiated and tested in the form of two prototype setups: a wooden table covered with a printed map and a glass case containing a scale model. The paper also discusses key issues stemming from experience and observations in the course of qualitative evaluation sessions.
BibTeX:
@inproceedings{GrammenosMichelZabulisEtAl2011a,
  author = {Grammenos, Dimitris and Michel, Damien and Zabulis, Xenophon and Argyros, Antonis A},
  title = {PaperView: augmenting physical surfaces with location-aware digital information},
  booktitle = {ACM Tangible, Embedded, and Embodied Interaction (TEI 2011)},
  publisher = {ACM},
  year = {2011},
  month = {January},
  pages = {57--60},
  address = {Funchal, Portugal},
  url = {http://users.ics.forth.gr/ argyros/res_paperview.html},
  projects =  {AMIPROJ},
  doi = {10.1145/1935701.1935713},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2011_01_tei_paperview.pdf},
  videolink = {https://youtu.be/ZxqUEYxc5FA?list=PL51573060F0131D04}
}
► D. Michel, A.A. Argyros and M.I.A. Lourakis, "Horizon matching for localizing unordered panoramic images", Computer Vision and Image Understanding, Elsevier, vol. 114, no. 2, pp. 274-285, 2010. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: There is currently an abundance of vision algorithms which, provided with a sequence of images that have been acquired from sufficiently close successive 3D locations, are capable of determining the relative positions of the viewpoints from which the images have been captured. However, very few of these algorithms can cope with unordered image sets. This paper presents an efficient method for recovering the position and orientation parameters corresponding to the viewpoints of a set of panoramic images for which no a priori order information is available, along with certain structure information regarding the imaged environment. The proposed approach assumes that all images have been acquired from a constant height above a planar ground and operates sequentially, employing the Levenshtein distance to deduce the spatial proximity of image viewpoints and thus determine the order in which images should be processed. The Levenshtein distance also provides matches between imaged points, from which their corresponding environment points can be reconstructed. Image matching with the aid of the Levenshtein distance forms the crux of an iterative process that alternates between image localization from multiple reconstructed points and point reconstruction from multiple image projections, until all views have been localized. Periodic refinement of the reconstruction with the aid of bundle adjustment, distributes the reconstruction error among images. The approach is demonstrated on several unordered sets of panoramic images obtained in indoor environments.
BibTeX:
@article{MichelArgyrosLourakis2010a,
  author = {Michel, Damien and Argyros, Antonis A and Lourakis, Manolis I A},
  title = {Horizon matching for localizing unordered panoramic images},
  journal = {Computer Vision and Image Understanding},
  publisher = {Elsevier},
  year = {2010},
  volume = {114},
  number = {2},
  pages = {274--285},
  url = {http://users.ics.forth.gr/ argyros/res_pan_slam.html},
  doi = {10.1016/j.cviu.2009.03.006},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2010_02_journal_cviu_omni_localization.pdf},
  videolink = {http://users.ics.forth.gr/ argyros/imgvideo/reconsProgress2frames.avi}
}
► V. Papadourakis and A.A. Argyros, "Multiple objects tracking in the presence of long-term occlusions", Computer Vision and Image Understanding, Elsevier, vol. 114, no. 7, pp. 835-846, 2010. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: We present a robust object tracking algorithm that handles spatially extended and temporally long object occlusions. The proposed approach is based on the concept of “object permanence” which suggests that a totally occluded object will re-emerge near its occluder. The proposed method does not require prior training to account for differences in the shape, size, color or motion of the objects to be tracked. Instead, the method automatically and dynamically builds appropriate object representations that enable robust and effective tracking and occlusion reasoning. The proposed approach has been evaluated on several image sequences showing either complex object manipulation tasks or human activity in the context of surveillance applications. Experimental results demonstrate that the developed tracker is capable of handling several challenging situations, where the labels of objects are correctly identified and maintained over time, despite the complex interactions among the tracked objects that lead to several layers of occlusions.
BibTeX:
@article{PapadourakisArgyros2010a,
  author = {Papadourakis, Vasilis and Argyros, Antonis A},
  title = {Multiple objects tracking in the presence of long-term occlusions},
  journal = {Computer Vision and Image Understanding},
  publisher = {Elsevier},
  year = {2010},
  volume = {114},
  number = {7},
  pages = {835--846},
  url = {http://users.ics.forth.gr/ argyros/res_occlusions.html},
  projects =  {GRASP},
  doi = {10.1016/j.cviu.2010.02.003},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2010_07_journal_cviu_occlusions.pdf},
  videolink = {https://youtu.be/MiLah8Q0TWk}
}
► K. Papoutsakis and A.A. Argyros, "Object Tracking and Segmentation in a Closed Loop", In Advances in Visual Computing (ISVC 2010), Springer, pp. 405-416, Las Vegas, Nevada, USA, November 2010. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: We introduce a new method for integrated tracking and segmentation of a single non-rigid object in an monocular video, captured by a possibly moving camera. A closed-loop interaction between EM-like color-histogram-based tracking and Random Walker-based image segmentation is proposed, which results in reduced tracking drifts and in fine object segmentation. More specifically, pixel-wise spatial and color image cues are fused using Bayesian inference to guide object segmentation. The spatial properties and the appearance of the segmented objects are exploited to initialize the tracking algorithm in the next step, closing the loop between tracking and segmentation. As confirmed by experimental results on a variety of image sequences, the proposed approach efficiently tracks and segments previously unseen objects of varying appearance and shape, under challenging environmental conditions.
BibTeX:
@inproceedings{PapoutsakisArgyros2010a,
  author = {Papoutsakis, Konstantinos and Argyros, Antonis A},
  title = {Object Tracking and Segmentation in a Closed Loop},
  booktitle = {Advances in Visual Computing (ISVC 2010)},
  publisher = {Springer},
  year = {2010},
  month = {November},
  pages = {405--416},
  address = {Las Vegas, Nevada, USA},
  url = {http://users.ics.forth.gr/ argyros/res_trackingsegmentation.html},
  projects =  {GRASP},
  doi = {10.1007/978-3-642-17289-2_39},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2010_12_isvc_trackingsegmentation.pdf}
}
► X. Zabulis, T. Sarmis, K. Tzevanidis, P. Koutlemanis, D. Grammenos and A.A. Argyros, "A Platform for Monitoring Aspects of Human Presence in Real-Time", In Advances in Visual Computing (ISVC 2010), Springer, pp. 584-595, Las Vegas, Nevada, USA, November 2010. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: In this paper, the design and implementation of a hardware/software platform for parallel and distributed multiview vision processing is presented. The platform is focused at supporting the monitoring of human presence in indoor environments. Its architecture is focused at increased throughput through process pipelining as well as at reducing communication costs and hardware requirements. Using this platform, we present efficient implementations of basic visual processes such as person tracking, textured visual hull computation and head pose estimation. Using the proposed platform multiview visual operations can be combined and third-party ones integrated, to ultimately facilitate the development of interactive applications that employ visual input. Computational performance is benchmarked comparatively to state of the art and the efficacy of the approach is qualitatively assessed in the context of already developed applications related to interactive environment.
BibTeX:
@inproceedings{ZabulisSarmisTzevanidisEtAl2010a,
  author = {Zabulis, Xenophon and Sarmis, Thomas and Tzevanidis, Konstantinos and Koutlemanis, Panayotis and Grammenos, Dimitris and Argyros, Antonis A},
  title = {A Platform for Monitoring Aspects of Human Presence in Real-Time},
  booktitle = {Advances in Visual Computing (ISVC 2010)},
  publisher = {Springer},
  year = {2010},
  month = {November},
  pages = {584--595},
  address = {Las Vegas, Nevada, USA},
  url = {http://users.ics.forth.gr/ argyros/res_humanpresence.html},
  projects =  {AMIPROJ},
  doi = {10.1007/978-3-642-17274-8_57},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2010_12_isvc_humanpresence.pdf}
}
► K. Tzevanidis, X. Zabulis, T. Sarmis, P. Koutlemanis, N. Kyriazis and A.A. Argyros, "From Multiple Views to Textured 3D Meshes: A GPU-Powered Approach", In European Conference on Computer Vision Workshops (CVGPU 2010 - ECCVW 2010), Springer, pp. 384-397, Heraklion, Crete, Greece, September 2010. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: We present work on exploiting modern graphics hardware towards the real-time production of a textured 3D mesh representation of a scene observed by a multicamera system. The employed computational infrastructure consists of a network of four PC workstations each of which is connected to a pair of cameras. One of the PCs is equipped with a GPU that is used for parallel computations. The result of the processing is a list of texture mapped triangles representing the reconstructed surfaces. In contrast to previous works, the entire processing pipeline (foreground segmentation, 3D reconstruction, 3D mesh computation, 3D mesh smoothing and texture mapping) has been implemented on the GPU. Experimental results demonstrate that an accurate, high resolution, texture-mapped 3D reconstruction of a scene observed by eight cameras is achievable in real time.
BibTeX:
@inproceedings{TzevanidisZabulisSarmisEtAl2010a,
  author = {Tzevanidis, Konstantinos and Zabulis, Xenophon and Sarmis, Thomas and Koutlemanis, Panayotis and Kyriazis, Nikolaos and Argyros, Antonis A},
  title = {From Multiple Views to Textured 3D Meshes: A GPU-Powered Approach},
  booktitle = {European Conference on Computer Vision Workshops (CVGPU 2010 - ECCVW 2010)},
  publisher = {Springer},
  year = {2010},
  month = {September},
  pages = {384--397},
  address = {Heraklion, Crete, Greece},
  url = {http://users.ics.forth.gr/ argyros/res_gpu3Drec.html},
  projects =  {GRASP,AMIPROJ},
  doi = {10.1007/978-3-642-35740-4_30},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2010_09_cvgpu_3Dreconstruction.pdf},
  videolink = {https://youtu.be/n0KC7wL_D_Q}
}
► X. Zabulis, D. Grammenos, T. Sarmis, K. Tzevanidis and A.A. Argyros, "Exploration of Large-scale Museum Artifacts through Non-instrumented, Location-based, Multi-user Interaction", In International Symposium on Virtual Reality, Archaeology and Intelligent Cultural Heritage (VAST 2010), pp. 155-162, Paris, France, September 2010. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: This paper presents a system that supports the exploration of digital representations of large-scale museum artifacts in through non-instrumented, location-based interaction. The system employs a state-of-the-art computer vision system, which localizes and tracks multiple visitors. The artifact is presented in a wall-sized projection screen and it is visually annotated with text and images according to the location as well as walkthrough trajectories of the tracked visitors. The system is evaluated in terms of computational performance, localization accuracy, tracking robustness and usability.
BibTeX:
@inproceedings{ZabulisGrammenosSarmisEtAl2010a,
  author = {Zabulis, Xenophon and Grammenos, Dimitris and Sarmis, Thomas and Tzevanidis, Konstantinos and Argyros, Antonis A},
  title = {Exploration of Large-scale Museum Artifacts through Non-instrumented, Location-based, Multi-user Interaction},
  booktitle = {International Symposium on Virtual Reality, Archaeology and Intelligent Cultural Heritage (VAST 2010)},
  year = {2010},
  month = {September},
  pages = {155--162},
  address = {Paris, France},
  url = {http://users.ics.forth.gr/ argyros/res_humanpresence.html},
  projects =  {AMIPROJ},
  doi = {10.2312/VAST/VAST10/155-162},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2010_09_vast_localization.pdf}
}
► I. Oikonomidis, N. Kyriazis and A.A. Argyros, "Markerless and Efficient 26-DOF Hand Pose Recovery", In Asian Conference on Computer Vision (ACCV 2010), Springer, pp. 744-757, Queenstown, New Zealand, April 2010. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: We present a novel method that, given a sequence of synchronized views of a human hand, recovers its 3D position, orientation and full articulation parameters. The adopted hand model is based on properly selected and assembled 3D geometric primitives. Hypothesized configurations/poses of the hand model are projected to different camera views and image features such as edge maps and hand silhouettes are computed. An objective function is then used to quantify the discrepancy between the predicted and the actual, observed features. The recovery of the 3D hand pose amounts to estimating the parameters that minimize this objective function which is performed using Particle Swarm Optimization. All the basic components of the method (feature extraction, objective function evaluation, optimization process) are inherently parallel. Thus, a GPU-based implementation achieves a speedup of two orders of magnitude over the case of CPU processing. Extensive experimental results demonstrate qualitatively and quantitatively that accurate 3D pose recovery of a hand can be achieved robustly at a rate that greatly outperforms the current state of the art.
BibTeX:
@inproceedings{OikonomidisKyriazisArgyros2010a,
  author = {Oikonomidis, Iason and Kyriazis, Nikolaos and Argyros, Antonis A},
  title = {Markerless and Efficient 26-DOF Hand Pose Recovery},
  booktitle = {Asian Conference on Computer Vision (ACCV 2010)},
  publisher = {Springer},
  year = {2010},
  month = {April},
  pages = {744--757},
  address = {Queenstown, New Zealand},
  url = {http://users.ics.forth.gr/ argyros/res_3Dhandpose.html},
  projects =  {GRASP},
  doi = {10.1007/978-3-642-19318-7_58},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2010_11_ACCV_3Dhandpose.pdf}
}
► X. Zabulis, H. Baltzakis and A.A. Argyros, "Vision-Based Hand Gesture Recognition for Human-Computer Interaction", The Universal Access Handbook, LEA, pp. 34.1-34.30, 2009. [BibTeX] [DOI] [PDF]
BibTeX:
@incollection{ZabulisBaltzakisArgyros2009a,
  author = {Zabulis, Xenophon and Baltzakis, Haris and Argyros, Antonis A},
  title = {Vision-Based Hand Gesture Recognition for Human-Computer Interaction},
  booktitle = {The Universal Access Handbook},
  publisher = {LEA},
  year = {2009},
  pages = {34.1--34.30},
  file = {C:\Users\argyros\OneDrive - ΙΔΡΥΜΑ ΤΕΧΝΟΛΟΓΙΑΣ ΚΑΙ ΕΡΕΥΝΑΣ\antonis\professional\html\mypapers\009_06_book_hci_gestures.pdf:PDF},
  projects =  {MUSCLE,XENIOS,INDIGO},
  doi = {10.1201/9781420064995-c34},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2009_06_book_hci_gestures.pdf}
}
► M.I.A. Lourakis and A.A. Argyros, "SBA: A software package for generic sparse bundle adjustment", ACM Transactions on Mathematical Software (TOMS), ACM, vol. 36, no. 1, 2009. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: Bundle adjustment constitutes a large, nonlinear least-squares problem that is often solved as the last step of feature-based structure and motion estimation computer vision algorithms to obtain optimal estimates. Due to the very large number of parameters involved, a general purpose least-squares algorithm incurs high computational and memory storage costs when applied to bundle adjustment. Fortunately, the lack of interaction among certain subgroups of parameters results in the corresponding Jacobian being sparse, a fact that can be exploited to achieve considerable computational savings. This article presents sba, a publicly available C/C++ software package for realizing generic bundle adjustment with high efficiency and flexibility regarding parameterization.
BibTeX:
@article{LourakisArgyros2009a,
  author = {Lourakis, Manolis I A and Argyros, Antonis A},
  title = {SBA: A software package for generic sparse bundle adjustment},
  journal = {ACM Transactions on Mathematical Software (TOMS)},
  publisher = {ACM},
  year = {2009},
  volume = {36},
  number = {1},
  url = {http://users.ics.forth.gr/ lourakis/sba/},
  doi = {10.1145/1486525.1486527},
  pdflink = {http://doi.acm.org/10.1145/1486525.1486527}
}
► M. Vincze, M. Zillich, W. Ponweiser, V. Hlavác, J. Matas, S. Obdrzálek, H. Buxton, J. Howell, K. Sage, A.A. Argyros, C. Eberst and G. Umgeher, "Integrated vision system for the semantic interpretation of activities where a person handles objects", Computer Vision and Image Understanding, Elsevier, vol. 113, no. 6, pp. 682-692, 2009. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: Interpretation of human activity is primarily known from surveillance and video analysis tasks and concerned with the persons alone. In this paper we present an integrated system that gives a natural language interpretation of activities where a person handles objects. The system integrates low-level image components such as hand and object tracking, detection and recognition, with high-level processes such as spatio-temporal object relationship generation, posture and gesture recognition, and activity reasoning. A task-oriented approach focuses processing to achieve near real-time and to react depending on the situation context.
BibTeX:
@article{VinczeZillichPonweiserEtAl2009a,
  author = {Vincze, Markus and Zillich, Michael and Ponweiser, Wolfgang and Hlavác, Václav and Matas, Jiri and Obdrzálek, Stepán and Buxton, Hilary and Howell, Jonathan and Sage, Kingsley and Argyros, Antonis A and Eberst, Christof and Umgeher, Gerald},
  title = {Integrated vision system for the semantic interpretation of activities where a person handles objects},
  journal = {Computer Vision and Image Understanding},
  publisher = {Elsevier},
  year = {2009},
  volume = {113},
  number = {6},
  pages = {682--692},
  url = {http://users.ics.forth.gr/ argyros},
  projects =  {ACTIPRET},
  doi = {10.1016/j.cviu.2008.10.008},
  pdflink = {http://dx.doi.org/10.1016/j.cviu.2008.10.008},
  videolink = {http://users.ics.forth.gr/ argyros/imgvideo/ActipretVideo.mpg}
}
► T. Sarmis, X. Zabulis and A.A. Argyros, "A Software Platform for the Acquisition and Online Processing of Images in a Camera Network", ERCIM News, no. 76, 2009. [BibTeX] [PDF] [URL]
BibTeX:
@periodical{SarmisZabulisArgyros2009b,
  author = {Sarmis, Thomas and Zabulis, Xenophon and Argyros, Antonis A},
  title = {A Software Platform for the Acquisition and Online Processing of Images in a Camera Network},
  journal = {ERCIM News},
  year = {2009},
  number = {76},
  url = {http://users.ics.forth.gr/ argyros/res_humanpresence.html},
  projects =  {AMIPROJ},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2009_01_ercimnews_sensorweb.pdf}
}
► T. Sarmis, X. Zabulis and A.A. Argyros, "A checkerboard detection utility for intrinsic and extrinsic camera cluster calibration", FORTH-ICS, TR-397, 2009. [BibTeX] [PDF] [URL]
BibTeX:
@techreport{SarmisZabulisArgyros2009a,
  author = {Sarmis, Thomas and Zabulis, Xenophon and Argyros, Antonis A},
  title = {A checkerboard detection utility for intrinsic and extrinsic camera cluster calibration},
  school = {FORTH-ICS},
  year = {2009},
  number = {TR-397},
  url = {http://users.ics.forth.gr/ argyros},
  projects =  {AMIPROJ},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2009_08_tr397_calibration.pdf}
}
► D. Grammenos, X. Zabulis, A.A. Argyros and C. Stephanidis, "FORTH-ICS Internal RTD Programme Ambient Intelligence and Smart Environments", In European Conference on Ambient Intelligence (AMI 2009), Saltsburg, Austria, November 2009. [Abstract] [BibTeX] [PDF]
Abstract: This paper introduces the horizontal, interdisciplinary, cross-thematic RTD Programme in the field of Ambient Intelligence which has recently been initiated by the Institute of Computer Science of the Foundation for Research and Technology Hellas, aiming to contribute towards the creation and provision of pioneering human-centric AmI technologies and smart environments.
BibTeX:
@inproceedings{GrammenosZabulisArgyrosEtAl2009a,
  author = {Grammenos, Dimitris and Zabulis, Xenophon and Argyros, Antonis A and Stephanidis, Constantine},
  title = {FORTH-ICS Internal RTD Programme Ambient Intelligence and Smart Environments},
  booktitle = {European Conference on Ambient Intelligence (AMI 2009)},
  year = {2009},
  month = {November},
  address = {Saltsburg, Austria},
  projects =  {AMIPROJ},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2009_11_AmI09_AmI.pdf}
}
► I. Oikonomidis and A.A. Argyros, "Deformable 2D Shape Matching Based on Shape Contexts and Dynamic Programming", In Advances in Visual Computing (ISVC 2009), Springer, pp. 460-469, Las Vegas, Nevada, USA, November 2009. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: This paper presents a method for matching closed, 2D shapes (2D object silhouettes) that are represented as an ordered collection of shape contexts [1]. Matching is performed using a recent method that computes the optimal alignment of two cyclic strings in sub-cubic runtime. Thus, the proposed method is suitable for efficient, near real-time matching of closed shapes. The method is qualitatively and quantitatively evaluated using several datasets. An application of the method for joint detection in human figures is also presented.
BibTeX:
@inproceedings{OikonomidisArgyros2009a,
  author = {Oikonomidis, Iason and Argyros, Antonis A},
  title = {Deformable 2D Shape Matching Based on Shape Contexts and Dynamic Programming},
  booktitle = {Advances in Visual Computing (ISVC 2009)},
  publisher = {Springer},
  year = {2009},
  month = {November},
  pages = {460--469},
  address = {Las Vegas, Nevada, USA},
  url = {http://users.ics.forth.gr/ argyros/res_shapematching.html},
  projects =  {GRASP},
  doi = {10.1007/978-3-642-10520-3_43},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2009_11_isvc_shape_matching.pdf}
}
► I. Cheng, D. Michel, A.A. Argyros and A. Basu, "A HIMI model for collaborative multi-touch multimedia education", In Proceedings of the 2009 workshop on Ambient media computing, ACM, pp. 3-12, Beijing, China, October 2009. [Abstract] [BibTeX] [PDF]
Abstract: Educational testing and learning have evolved from using standard True/False, fill-in-the-blank and multiple choice on paper to more visually enriched formats using interactive multimedia content on digital displays. However, traditional educational application interfaces are primarily mouse-driven, which prevents multiple users working simultaneously. Although touch-based displays have emerged and inspired new developments, they are mainly used in simple tasks. In this paper we show how the multi-touch technology can be extended to collaborative learning and testing at a larger scale, using an existing education implementation for illustration. We propose a Human-Intention-Machine-Interpretation (HIMI) model, which applies a graph-based approach to recognize hand gestures and interpret user intentions. Our focus is not to build a new multitouch system but to make use of the existing multi-touch technology to enhance learning performance. The HIMI model not only facilitates natural interactions using hand movements on simple tasks, but also supports complex collaborative operations. Our contribution lies in embedding the multi-touch technology in multimedia education, providing a multi-user learning and testing environment which would not have been possible using traditional input devices. We formalize a conceptual model to uniquely interpret user intentions via touch states, state transitions and transition associations. We also propose a set of hand gestures for working with multimedia educational items. User evaluations are conducted to show the feasibility of the proposed hand gestures.
BibTeX:
@inproceedings{ChengMichelArgyrosEtAl2009a,
  author = {Cheng, Irene and Michel, Damien and Argyros, Antonis A and Basu, Anup},
  title = {A HIMI model for collaborative multi-touch multimedia education},
  booktitle = {Proceedings of the 2009 workshop on Ambient media computing},
  publisher = {ACM},
  year = {2009},
  month = {October},
  pages = {3--12},
  address = {Beijing, China},
  projects =  {AMIPROJ},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2009_10_amc09_eblackboard_education.pdf}
}
► X. Zabulis, T. Sarmis and A.A. Argyros, "3D Head Pose Estimation from Multiple Distant Views", In British Machine Vision Conference (BMVC 2009), BMVA, pp. 1-12, London, UK, September 2009. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: A method for human head pose estimation in multicamera environments is proposed. The method computes the textured visual hull of the subject and unfolds the texture of the head on a hypothetical sphere around it, whose parameterization is iteratively rotated so that the face eventually occurs on its equator. This gives rise to a spherical image, in which face detection is simplified, because exactly one frontal face is guaranteed to appear in it. In this image, the face center yields two components of pose (yaw, pitch), while the third (roll) is retrieved from the orientation of the major symmetry axis of the face. Face detection applied on the original images reduces the required iterations and anchors tracking drift. The method is demonstrated and evaluated in several data sets, including ones with known ground truth. Experimental results show that the proposed method is accurate and robust to distant imaging, despite the low-resolution appearance of subjects.
BibTeX:
@inproceedings{ZabulisSarmisArgyros2009a,
  author = {Zabulis, Xenophon and Sarmis, Thomas and Argyros, Antonis A},
  title = {3D Head Pose Estimation from Multiple Distant Views},
  booktitle = {British Machine Vision Conference (BMVC 2009)},
  publisher = {BMVA},
  year = {2009},
  month = {September},
  volume = {1},
  number = {2},
  pages = {1--12},
  address = {London, UK},
  url = {http://www.ics.forth.gr/cvrl/headpose/},
  doi = {10.5244/C.23.118},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2009_09_bmvc_headpose.pdf},
  videolink = {https://youtu.be/x3GUYs9snBs}
}
► D. Grammenos, Y. Georgalis, N. Partarakis, X. Zabulis, T. Sarmis, S. Kartakis, P. Tourlakis, A.A. Argyros and C. Stephanidis, "Rapid Prototyping of an AmI-Augmented Office Environment Demonstrator", In Human-Computer Interaction. Ambient, Ubiquitous and Intelligent Interaction, Springer, pp. 397-406, San Diego, CA, USA, July 2009. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: This paper presents the process and tangible outcomes of a rapid prototyping activity towards the creation of a demonstrator, showcasing the potential use and effect of Ambient Intelligence technologies in a typical office environment. In this context, the hardware and software components used are described, as well as the interactive behavior of the demonstrator. Additionally, some conclusions stemming from the experience gained are presented, along with pointers for future research and development work.
BibTeX:
@inproceedings{GrammenosGeorgalisPartarakisEtAl2009a,
  author = {Grammenos, Dimitris and Georgalis, Yannis and Partarakis, Nikolaos and Zabulis, Xenophon and Sarmis, Thomas and Kartakis, Sokratis and Tourlakis, Panagiotis and Argyros, Antonis A and Stephanidis, Constantine},
  title = {Rapid Prototyping of an AmI-Augmented Office Environment Demonstrator},
  booktitle = {Human-Computer Interaction. Ambient, Ubiquitous and Intelligent Interaction},
  publisher = {Springer},
  year = {2009},
  month = {July},
  pages = {397--406},
  address = {San Diego, CA, USA},
  projects =  {AMIPROJ},
  doi = {10.1007/978-3-642-02580-8_43},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2009_07_hci_smartoffice.pdf}
}
► G. López-Nicolás, M. Sfakiotakis, D.P. Tsakiris, A.A. Argyros, C. Sagüés and J.J. Guerrero, "Visual homing for undulatory robotic locomotion", In IEEE International Conference on Robotics and Automation (ICRA 2009), IEEE, pp. 2629-2636, Kobe, Japan, May 2009. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: This paper addresses the problem of vision-based closed-loop control for undulatory robots. We present an image-based visual servoing scheme, which drives the robot to a desired location specified by a target image, without explicitly estimating its pose. Instead, the control relies on the computation of the epipolar geometry between the current and target images. We analyze controllability and stability of the proposed control scheme, which is validated by simulation studies using the SIMUUN computational tools. Preliminary experiments, involving the Nereisbot undulatory robotic prototype, are also presented.
BibTeX:
@inproceedings{Lopez-NicolasSfakiotakisTsakirisEtAl2009a,
  author = {Gonzalo López-Nicolás and Sfakiotakis, Michael and Tsakiris, Dimitris P and Argyros, Antonis A and Sagüés, Carlos and Guerrero, José Jesús},
  title = {Visual homing for undulatory robotic locomotion},
  booktitle = {IEEE International Conference on Robotics and Automation (ICRA 2009)},
  publisher = {IEEE},
  year = {2009},
  month = {May},
  pages = {2629--2636},
  address = {Kobe, Japan},
  url = {http://users.ics.forth.gr/ argyros/res_undulatory.html},
  doi = {10.1109/ROBOT.2009.5152432},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2009_05_icra_homing.pdf},
  videolink = {http://users.ics.forth.gr/ argyros/imgvideo/videoUndulatoryDivx6.avi}
}
► D. Michel, A.A. Argyros, D. Grammenos, X. Zabulis and T. Sarmis, "Building a Multi-Touch Display Based on Computer Vision Techniques", In Machine Vision Applications (MVA 2009), pp. 74-77, Hiyoshi Campus, Keio University, Japan, May 2009. [Abstract] [BibTeX] [PDF] [URL] [VIDEO]
Abstract: We present the development of a multi-touch display based on computer vision techniques. The developed system is built upon low cost, off-the-shelf hardware components and a careful selection of computer vision techniques. The resulting system is capable of detecting and tracking several objects that may move freely on the surface of a wide projection screen. It also provides additional information regarding the detected and tracked objects, such as their orientation, their full contour, etc. All of the above are achieved robustly, in real time and regardless of the visual appearance of what may be independently projected on the projection screen. We also present indicative results from
the exploitation of the developed system in three application scenarios and discuss directions for further research.
BibTeX:
@inproceedings{MichelArgyrosGrammenosEtAl2009a,
  author = {Michel, Damien and Argyros, Antonis A and Grammenos, Dimitris and Zabulis, Xenophon and Sarmis, Thomas},
  title = {Building a Multi-Touch Display Based on Computer Vision Techniques},
  booktitle = {Machine Vision Applications (MVA 2009)},
  year = {2009},
  month = {May},
  pages = {74--77},
  address = {Hiyoshi Campus, Keio University, Japan},
  url = {http://users.ics.forth.gr/ argyros/res_multitouch.html},
  projects =  {AMIPROJ},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2009_05_mva_smartboard.pdf},
  videolink = {https://youtu.be/l6y2clf73-8?list=PL51573060F0131D04}
}
► X. Zabulis, T. Sarmis, D. Grammenos and A.A. Argyros, "A Multicamera Vision System Supporting the Development of Wide-Area Exertainment Applications", In Machine Vision Applications (MVA 2009), pp. 269-272, Keio University, Japan, May 2009. [Abstract] [BibTeX] [PDF] [URL]
Abstract: In this paper, the application of computer vision techniques to the localization of multiple persons in a relatively wide gaming terrain is presented. Multiple views are employed both for terrain coverage, but most importantly, for treatment of occlusions. Through the appropriate selection of lightweight operations and acceleration strategies, an adequate frame rate is achieved despite the large volume of input data. The resulting system is employed in the development of multiplayer entertainment applications, which are demonstrated and evaluated.
BibTeX:
@inproceedings{ZabulisSarmisGrammenosEtAl2009a,
  author = {Zabulis, Xenophon and Sarmis, Thomas and Grammenos, Dimitris and Argyros, Antonis A},
  title = {A Multicamera Vision System Supporting the Development of Wide-Area Exertainment Applications},
  booktitle = {Machine Vision Applications (MVA 2009)},
  year = {2009},
  month = {May},
  pages = {269--272},
  address = {Keio University, Japan},
  url = {http://users.ics.forth.gr/ argyros/res_humanpresence.html},
  projects =  {AMIPROJ},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2009_05_mva_exertainment.pdf}
}
► H. Baltzakis and A.A. Argyros, "Propagation of Pixel Hypotheses for Multiple Objects Tracking", In Advances in Visual Computing (ISVC 2009), Springer, pp. 140-149, Las Vegas, Nevada, USA, January 2009. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: In this paper we propose a new approach for tracking multiple objects in image sequences. The proposed approach differs from existing ones in important aspects of the representation of the location and the shape of tracked objects and of the uncertainty associated with them. The location and the speed of each object is modeled as a discrete time, linear dynamical system which is tracked using Kalman filtering. Information about the spatial distribution of the pixels of each tracked object is passed on from frame to frame by propagating a set of pixel hypotheses, uniformly sampled from the original object’s projection to the target frame using the object’s current dynamics, as estimated by the Kalman filter. The density of the propagated pixel hypotheses provides a novel metric that is used to associate image pixels with existing object tracks by taking into account both the shape of each object and the uncertainty associated with its track. The proposed tracking approach has been developed to support face and hand tracking for human-robot interaction. Nevertheless, it is readily applicable to a much broader class of multiple objects tracking problems.
BibTeX:
@inproceedings{BaltzakisArgyros2009a,
  author = {Baltzakis, Haris and Argyros, Antonis A},
  title = {Propagation of Pixel Hypotheses for Multiple Objects Tracking},
  booktitle = {Advances in Visual Computing (ISVC 2009)},
  publisher = {Springer},
  year = {2009},
  month = {January},
  pages = {140--149},
  address = {Las Vegas, Nevada, USA},
  projects =  {GRASP},
  doi = {10.1007/978-3-642-10520-3_13},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2009_11_isvc_tracking.pdf}
}
► K. Sage, J. Howell, H. Buxton and A.A. Argyros, "Learning temporal structure for task based control", Image and Vision Computing, Elsevier, vol. 26, no. 1, pp. 39-52, 2008. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: We present an extension for variable length Markov models (VLMMs) to allow for modelling of continuous input data and show that the generative properties of these VLMMs are a powerful tool for dealing with real world tracking issues. We explore methods for addressing the temporal correspondence problem in the context of a practical hand tracker, which is essential to support expectation in task-based control using these behavioural models. The hand tracker forms a part of a larger multi-component distributed system, providing 3-D hand position data to a gesture recogniser client. We show how the performance of such a hand tracker can be improved by using feedback from the gesture recogniser client. In particular, feedback based on the generative extrapolation of the recogniser’s internal models is shown to help the tracker deal with mid-term occlusion. We also show that VLMMs can be used as a means to inform
the prior in an expectation maximisation (EM) process used for joint spatial and temporal learning of image features.
BibTeX:
@article{SageHowellBuxtonEtAl2008a,
  author = {Sage, Kingsley and Howell, Jonathan and Buxton, Hilary and Argyros, Antonis A},
  title = {Learning temporal structure for task based control},
  journal = {Image and Vision Computing},
  publisher = {Elsevier},
  year = {2008},
  volume = {26},
  number = {1},
  pages = {39--52},
  url = {http://users.ics.forth.gr/ argyros/res_colortracking.html},
  projects =  {ACTIPRET},
  doi = {10.1016/j.imavis.2005.08.010},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2008_01_journal_ivc_vlmm.pdf}
}
► X. Zabulis, A.A. Argyros and D.P. Tsakiris, "Lumen detection for capsule endoscopy", In IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2008), IEEE, pp. 3921-3926, Nice, France, September 2008. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: In this paper, two visual cues are proposed, to be exploited for the navigation of active endoscopic capsules within the gastrointestinal (GI) tract. These cues consist of the detection and tracking of the lumen and of an illumination highlight in capsule endoscopy (CE) images. The proposed approach aims at developing vision algorithms which are robust with respect to the challenging imaging conditions encountered in the GI tract and the great variability of the acquired images. Cases where no or more than one lumens exists, are also detected. The proposed approach extends the state-of-the-art in lumen detection, and is demonstrated for in-vivo video sequences acquired from endoscopic capsules.
BibTeX:
@inproceedings{ZabulisArgyrosTsakiris2008a,
  author = {Zabulis, Xenophon and Argyros, Antonis A and Tsakiris, Dimitris P},
  title = {Lumen detection for capsule endoscopy},
  booktitle = {IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2008)},
  publisher = {IEEE},
  year = {2008},
  month = {September},
  pages = {3921--3926},
  address = {Nice, France},
  url = {http://users.ics.forth.gr/ argyros/res_lumen.html},
  projects =  {VECTOR},
  doi = {10.1109/IROS.2008.4650969},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2008_09_iros_lumen_detection.pdf},
  videolink = {https://youtu.be/q6OW2QGGRCQ}
}
► P. Nillius, J. Sullivan and A.A. Argyros, "Shading models for illumination and reflectance invariant shape detectors", In IEEE Computer Vision and Pattern Recognition (CVPR 2008), IEEE, pp. 1-8, Anchorage, Alaska, USA, June 2008. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: Many objects have smooth surfaces of a fairly uniform color, thereby exhibiting shading patterns that reveal information about its shape, an important clue to the nature of the object. This papers explores extracting this information from images, by creating shape detectors based on shading.
BibTeX:
@inproceedings{NilliusSullivanArgyros2008a,
  author = {Nillius, Peter and Sullivan, Josephine and Argyros, Antonis A},
  title = {Shading models for illumination and reflectance invariant shape detectors},
  booktitle = {IEEE Computer Vision and Pattern Recognition (CVPR 2008)},
  publisher = {IEEE},
  year = {2008},
  month = {June},
  pages = {1--8},
  address = {Anchorage, Alaska, USA},
  doi = {10.1109/CVPR.2008.4587773},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2008_06_cvpr_shape_detectors.pdf}
}
► H. Baltzakis, A.A. Argyros, M.I.A. Lourakis and P.E. Trahanias, "Tracking of Human Hands and Faces through Probabilistic Fusion of Multiple Visual Cues", In International Conference on Computer Vision Systems (ICVS 2008), Springer, pp. 33-42, Santorini, Greece, May 2008. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: This paper presents a new approach for real time detection and tracking of human hands and faces in image sequences. The proposed method builds upon our previous research on color-based tracking and extends it towards building a system capable of distinguishing between human hands, faces and other skin-colored regions in the image background. To achieve these goals, the proposed approach allows the utilization of additional information cues including motion information given by means of a background subtraction algorithm, and top-down information regarding the formed image segments such as their spatial location, velocity and shape. All information cues are combined under a probabilistic framework which furnishes the proposed approach with the ability to cope with uncertainty due to noise. The proposed approach runs in real time on a standard, personal computer. The presented experimental results, confirm the effectiveness of the proposed methodology and its advantages over previous approaches.
BibTeX:
@inproceedings{BaltzakisArgyrosLourakisEtAl2008a,
  author = {Baltzakis, Haris and Argyros, Antonis A and Lourakis, Manolis I A and Trahanias, Panos E},
  title = {Tracking of Human Hands and Faces through Probabilistic Fusion of Multiple Visual Cues},
  booktitle = {International Conference on Computer Vision Systems (ICVS 2008)},
  publisher = {Springer},
  year = {2008},
  month = {May},
  pages = {33--42},
  address = {Santorini, Greece},
  projects =  {MUSCLE,XENIOS,INDIGO},
  doi = {10.1007/978-3-540-79547-6_4},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2008_05_icvs_tracking_hands_faces.pdf}
}
► J. Romero, D. Kragic, V. Kyrki and A.A. Argyros, "Dynamic time warping for binocular hand tracking and reconstruction", In IEEE International Conference on Robotics and Automation (ICRA 2008), IEEE, pp. 2289-2294, Pasadena, California, USA, May 2008. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: We show how matching and reconstruction of contour points can be performed using dynamic time warping (DTW) for the purpose of 3D hand contour tracking. We evaluate the performance of the proposed algorithm in object manipulation activities and perform comparison with the iterative closest point (ICP) method.
BibTeX:
@inproceedings{RomeroKragicKyrkiEtAl2008a,
  author = {Romero, Javier and Kragic, Danica and Kyrki, Ville and Argyros, Antonis A},
  title = {Dynamic time warping for binocular hand tracking and reconstruction},
  booktitle = {IEEE International Conference on Robotics and Automation (ICRA 2008)},
  publisher = {IEEE},
  year = {2008},
  month = {May},
  pages = {2289--2294},
  address = {Pasadena, California, USA},
  doi = {10.1109/ROBOT.2008.4543555},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2008_05_icra_dynamic_time_warping.pdf}
}
► C. Stephanidis, A.A. Argyros, D. Grammenos and X. Zabulis, "Pervasive Computing@ICS-FORTH", In Workshop Pervasive Computing@Home, International Conference on Pervasive Computing, pp. 119-124, Sydney, Australia, May 2008. [BibTeX] [PDF]
BibTeX:
@inproceedings{StephanidisArgyrosGrammenosEtAl2008a,
  author = {Stephanidis, Constantine and Argyros, Antonis A and Grammenos, Dimitris and Zabulis, Xenophon},
  title = {Pervasive Computing@ICS-FORTH},
  booktitle = {Workshop Pervasive Computing@Home, International Conference on Pervasive Computing},
  year = {2008},
  month = {May},
  pages = {119--124},
  address = {Sydney, Australia},
  projects =  {ACTIPRET},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2008_05_pervasive08_icsami.pdf}
}
► A.A. Argyros, G. Bártfai, C. Eitzinger, Z. Kemény, B.C. Csáji, L. Kék, M.I.A. Lourakis, W. Reisner, W. Sandrisser, T. Sarmis and others, "Smart sensor based vision system for automated processes", Emerging Technologies, Robotics and Control Systems, International Society for Advanced Research, ISBN: 978-88-901928-9-5, 2007. [Abstract] [BibTeX] [PDF] [URL]
Abstract: A new approach is proposed for vision-based sensing and processing for process control and monitoring of automated processes. The proposed approach relies on a number of binary logical sensors defined over specific regions of interest in the viewed scene. On top of these elementary sensors, temporal and logical aggregation mechanisms realize hierarchies of compound logical functions, able to detect complex events. Finally, scenario verification mechanisms are employed to monitor the occurrence order and timing of expected and actual events. The proposed framework has been tested and validated in an application involving monitoring of automated processes, demonstrating that the proposed approach provides a promising concept of vision-based event detection. The described framework is being implemented on the Bi-i standalone cellular vision system which has the potential of replacing several conventional sensors used for process control and fault detection in automation.
BibTeX:
@incollection{ArgyrosBartfaiEitzingerEtAl2007a,
  author = {Argyros, Antonis A and Bártfai, Gusztáv and Eitzinger, Christian and Kemény, Zsolt and Csáji, Balázs Csanád and Kék, László and Lourakis, Manonis I A and Reisner, W and Sandrisser, W and Sarmis, Thomas and others},
  title = {Smart sensor based vision system for automated processes},
  booktitle = {Emerging Technologies, Robotics and Control Systems},
  publisher = {International Society for Advanced Research, ISBN: 978-88-901928-9-5},
  year = {2007},
  volume = {2},
  file = {C:\Users\argyros\OneDrive - ΙΔΡΥΜΑ ΤΕΧΝΟΛΟΓΙΑΣ ΚΑΙ ΕΡΕΥΝΑΣ\antonis\professional\html\mypapers\007_07_journal_internationalsar_multisens.pdf:PDF},
  projects =  {MULTISENS},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2007_07_journal_internationalsar_multisens.pdf}
}
► A.A. Argyros, G. Bártfai, C. Eitzinger, Z. Kemény, B.C. Csáji, L. Kék, M.I.A. Lourakis, W. Reisner, W. Sandrisser, T. Sarmis and others, "Smart sensor based vision system for automated processes", International Journal of Factory Automation, Robotics and Soft Computing, Thomson Scientific Journal, vol. 3, pp. 118-123, 2007. [Abstract] [BibTeX] [PDF] [URL]
Abstract: A new approach is proposed for vision-based sensing and processing for process control and monitoring of automated processes. The proposed approach relies on a number of binary logical sensors defined over specific regions of interest in the viewed scene. On top of these elementary sensors, temporal and logical aggregation mechanisms realize hierarchies of compound logical functions, able to detect complex events. Finally, scenario verification mechanisms are employed to monitor the occurrence order and timing of expected and actual events. The proposed framework has been tested and validated in an application involving monitoring of automated processes, demonstrating that the proposed approach provides a promising concept of vision-based event detection. The described framework is being implemented on the Bi-i standalone cellular vision system which has the potential of replacing several conventional sensors used for process control and fault detection in automation.
BibTeX:
@article{ArgyrosBartfaiEitzingerEtAl2007b,
  author = {Argyros, Antonis A and Bártfai, Gusztáv and Eitzinger, Christian and Kemény, Zsolt and Csáji, Balázs Csanád and Kék, László and Lourakis, Manonis I A and Reisner, W and Sandrisser, W and Sarmis, Thomas and others},
  title = {Smart sensor based vision system for automated processes},
  journal = {International Journal of Factory Automation, Robotics and Soft Computing},
  publisher = {Thomson Scientific Journal},
  year = {2007},
  volume = {3},
  pages = {118--123},
  url = {http://users.ics.forth.gr/ argyros/res_multisens.html},
  projects =  {MULTISENS},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2007_07_journal_internationalsar_multisens.pdf}
}
► M.I.A. Lourakis and A.A. Argyros, "Refining Single View Calibration With the Aid of Metric Scene Properties", Journal of WSCG, Václav Skala-UNION Agency, vol. 15, no. 1-3, pp. 129-134, 2007. [Abstract] [BibTeX] [PDF]
Abstract: Intrinsic camera calibration using a single image is possible provided that certain geometric objects such as orthogonal vanishing points and metric homographies can be estimated from the image and give rise to adequate constraints on the sought calibration parameters. In doing so, however, any additional metric information that might be available for the imaged scene is not always straightforward to accommodate. This paper puts forward a method for incorporating into the calibration procedure metric scene.
BibTeX:
@article{LourakisArgyros2007c,
  author = {Lourakis, Manolis I A and Argyros, Antonis A},
  title = {Refining Single View Calibration With the Aid of Metric Scene Properties},
  journal = {Journal of WSCG},
  publisher = {Václav Skala-UNION Agency},
  year = {2007},
  volume = {15},
  number = {1-3},
  pages = {129--134},
  projects =  {REPAINTER},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2007_xx_journal_wscg_svc.pdf}
}
► D. Michel, A.A. Argyros and M.I.A. Lourakis, "Localizing Unordered Panoramic Images Using the Levenshtein Distance", In IEEE International Conference on Computer Vision Workshops (OMNIVIS 2007 - ICCVW 2007), IEEE, pp. 1-7, Rio de Janeiro, Brazil, October 2007. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: This paper proposes a feature-based method for recovering the relative positions of the viewpoints of a set of panoramic images for which no a priori order information is available, along with certain structure information regarding the imaged environment. The proposed approach operates incrementally, employing the Levenshtein distance to deduce the spatial proximity of image viewpoints and thus determine the order in which images should be processed. The Levenshtein distance also provides matches between images, from which their underlying environment points can be recovered. Recovered points that are visible in multiple views permit the localization of more views which in turn allow the recovery of more points. The process repeats until all views have been localized. Periodic refinement of the reconstruction with the aid of bundle adjustment, distributes the reconstruction errors among images. The method is demonstrated on several unordered sets of panoramic images obtained in an indoor environment.
BibTeX:
@inproceedings{MichelArgyrosLourakis2007a,
  author = {Michel, Damien and Argyros, Antonis A and Lourakis, Manolis I A},
  title = {Localizing Unordered Panoramic Images Using the Levenshtein Distance},
  booktitle = {IEEE International Conference on Computer Vision Workshops (OMNIVIS 2007 - ICCVW 2007)},
  publisher = {IEEE},
  year = {2007},
  month = {October},
  pages = {1--7},
  address = {Rio de Janeiro, Brazil},
  url = {http://users.ics.forth.gr/ argyros/res_pan_slam.html},
  doi = {10.1109/ICCV.2007.4409200},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2007_10_omnivis_panoramic_slam_levenshtein.pdf},
  videolink = {http://users.ics.forth.gr/ argyros/imgvideo/reconsProgress2frames.avi}
}
► M.I.A. Lourakis and A.A. Argyros, "Enforcing Scene Constraints in Single View Reconstruction", In Eurographics 2007, pp. 45-48, Prague, Czech Republic, September 2007. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: Three-dimensional reconstruction from a single view is an under-constrained process that relies critically upon the availability of prior knowledge about the imaged scene. This knowledge is assumed to be supplied by a user in the form of geometric constraints such as coplanarity, parallelism, perpendicularity, etc, based on his/her interpretation of the scene. In the presence of noise, however, most of the existing methods yield reconstructions that only approximately satisfy the supplied geometric constraints. This paper proposes a novel single view reconstruction method that provides reconstructions which exactly satisfy all user-supplied constraints. This is achieved by first obtaining a preliminary reconstruction and then refining it in an extendable, constrained optimization framework.
BibTeX:
@inproceedings{LourakisArgyros2007a,
  author = {Lourakis, Manolis I A and Argyros, Antonis A},
  title = {Enforcing Scene Constraints in Single View Reconstruction},
  booktitle = {Eurographics 2007},
  year = {2007},
  month = {September},
  pages = {45--48},
  address = {Prague, Czech Republic},
  projects =  {MUSCLE,XENIOS,INDIGO},
  doi = {10.2312/egs.20071030},
  pdflink = {http://dx.doi.org/10.2312/egs.20071030}
}
► M.I.A. Lourakis and A.A. Argyros, "Accurate constraint-based modeling from a single perspective view", In Computer Graphics International (CGI 2007), Petropolis, RJ, Brazil, May 2007. [Abstract] [BibTeX] [PDF]
Abstract: Three-dimensional reconstruction from a single view is an under-constrained process that relies critically upon the availability of prior knowledge about the imaged scene. This knowledge is assumed to be supplied by a user in the form of geometric constraints such as coplanarity, parallelism, perpendicularity, etc, based on his/her interpretation of the scene. In the presence of noise, however, most of the existing methods yield reconstructions that only approximately satisfy
the supplied geometric constraints. This paper proposes a novel single view reconstruction method that provides reconstructions which exactly satisfy all user-supplied constraints. This is achieved by first obtaining a preliminary reconstruction and then refining it in an extendable, constrained optimization framework.
BibTeX:
@inproceedings{LourakisArgyros2007b,
  author = {Lourakis, Manolis I A and Argyros, Antonis A},
  title = {Accurate constraint-based modeling from a single perspective view},
  booktitle = {Computer Graphics International (CGI 2007)},
  year = {2007},
  month = {May},
  address = {Petropolis, RJ, Brazil},
  projects =  {REPAINTER},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2007_05_cgi_SVR.pdf}
}
► A.A. Argyros, "Building computers that can see", 2007. [BibTeX] [PDF]
BibTeX:
@periodical{Argyros2007a,
  author = {Argyros, Antonis A},
  title = {Building computers that can see},
  booktitle = {Kathimerini, The Economist (Greek newspaper)},
  year = {2007},
  month = {February},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2007_02_kathimerini_compvis.pdf}
}
► K.E. Bekris, A.A. Argyros and L.E. Kavraki, "Exploiting panoramic vision for bearing-only robot homing", Imaging beyond the pinhole camera, Springer, pp. 229-251, 2006. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: Omni-directional vision allows for the development of techniques for mobile robot navigation that have minimum perceptual requirements. In this work, we focus on robot navigation algorithms that do not require range information or metric maps of the environment. More specifically, we present a homing strategy that enables a robot to return to its home position after executing a long path. The proposed strategy relies on measuring the angle between pairs of features extracted from panoramic images, which can be achieved accurately and robustly. In the heart of the proposed homing strategy lies a novel, local control law that enables a robot to reach any position on the plane by exploiting the bearings of at least three landmarks of unknown position, without making assumptions regarding the robot’s orientation and without making use of a compass. This control law is the result of the unification of two other local control laws which guide the robot by monitoring the bearing of landmarks and which are able to reach complementary sets of goal positions on the plane. Long-range homing is then realized through the systematic application of the unified control law between automatically extracted milestone positions connecting the robot’s current position to the home position. Experimental results, conducted both in a simulated environment and on a robotic platform equipped with a panoramic camera validate the employed local control laws as well as the overall homing strategy. Moreover, they show that panoramic vision can assist in simplifying the perceptual processes required to support robust and accurate homing behaviors.
BibTeX:
@incollection{BekrisArgyrosKavraki2006a,
  author = {Bekris, Kostas E and Argyros, Antonis A and Kavraki, Lydia E},
  title = {Exploiting panoramic vision for bearing-only robot homing},
  booktitle = {Imaging beyond the pinhole camera},
  publisher = {Springer},
  year = {2006},
  pages = {229--251},
  file = {C:\Users\argyros\OneDrive - ΙΔΡΥΜΑ ΤΕΧΝΟΛΟΓΙΑΣ ΚΑΙ ΕΡΕΥΝΑΣ\antonis\professional\html\mypapers\006_xx_book_dagstuhl_robot_homing.pdf:PDF},
  doi = {10.1007/978-1-4020-4894-4_12},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2006_xx_book_dagstuhl_robot_homing.pdf},
  videolink = {http://users.ics.forth.gr/ argyros/imgvideo/snapshot.mpg}
}
► E. Tzamali, G. Akoumianakis, A.A. Argyros and Y.J. Stephanedes, "Improved design for vision-based incident detection in transportation systems using real-time view transformations", Journal of transportation engineering, American Society of Civil Engineers, vol. 132, no. 11, pp. 837-844, 2006. [Abstract] [BibTeX] [DOI] [URL]
Abstract: Advances in machine vision techniques have led to algorithms and integrated systems that can be applied in transportation engineering to improve surveillance and control. Despite these advances, certain problems in the effective integration of machine-vision based systems at complex intersections and complex freeway sections still remain. These are related to increasing system performance in the identification, analysis, and detection of the traffic state in real time. This work examines the feasibility of providing transformed visual input to existing machine-vision based systems, in order to gain increased efficiency and cost effectiveness of integrated transportation systems. Two transformations are developed, homography-based transformation and panoramic image reprojection. Homography-based transformation operates on video of the road scene, provided by classical cameras, and seeks to transform any view to a top-down view. This transforms the three-dimensional problem of image analysis for, e.g., road event detection to a two-dimensional one. Panoramic image reprojection employs panoramic cameras to reduce required hardware, and the complexity and cost incurred in obtaining the desired road view. The image reprojection technique allows the reconstruction of undistorted, perspectively correct views from panoramic images in real time. Tests at sites in Spain, the United Kingdom, and Greece are performed on-line and off-line in combination with operating machine-vision based incident detection systems. Test results indicate that the two methods simplify the input provided to machine vision, and reduce the workload and amount of hardware in implementing complex machine-vision based systems for incident detection. Both modules can be integrated into incident detection systems to improve their overall efficiency and ease of application.
BibTeX:
@article{TzamaliAkoumianakisArgyrosEtAl2006a,
  author = {Tzamali, Eleftheria and Akoumianakis, George and Argyros, Antonis A and Stephanedes, Yorgos J},
  title = {Improved design for vision-based incident detection in transportation systems using real-time view transformations},
  journal = {Journal of transportation engineering},
  publisher = {American Society of Civil Engineers},
  year = {2006},
  volume = {132},
  number = {11},
  pages = {837--844},
  url = {http://users.ics.forth.gr/ argyros/res_pan_geom.html},
  projects =  {PRIME},
  doi = {10.1061/(ASCE)0733-947X(2006)132:11(837)}
}
► M.I.A. Lourakis and A.A. Argyros, "Exploiting the Sparseness of Bundle Adjustment for Efficient 3D Reconstruction", In European Conference on Computer Vision Workshops (CIMCV 2006 - ECCVW 2006), Graz, Austria, 2006. [Abstract] [BibTeX] [PDF]
Abstract: Bundle adjustment amounts to a large, nonlinear least squares optimization problem that is often used as the last step of feature-based structure and motion estimation vision algorithms to obtain optimal estimates. Due to the very large number of parameters involved, a general purpose implementation of a nonlinear least squares algorithm incurs high computational and memory storage costs when applied to bundle adjustment. Fortunately, the lack of interaction among certain sub-groups of parameters results in the corresponding Jacobian exhibiting a sparse block structure. In this paper we outline the mathematics of sba, our publicly available software package for generic bundle adjustment that exploits sparseness to achieve considerable computational savings. In addition, we provide experimental results demonstrating that sba can efficiently handle large bundle adjustment problems which would be intractable with general purpose nonlinear least squares implementations.
BibTeX:
@inproceedings{LourakisArgyros2006b,
  author = {Lourakis, Manolis I A and Argyros, Antonis A},
  title = {Exploiting the Sparseness of Bundle Adjustment for Efficient 3D Reconstruction},
  booktitle = {European Conference on Computer Vision Workshops (CIMCV 2006 - ECCVW 2006)},
  year = {2006},
  address = {Graz, Austria},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2006_05_cimcv_sba.pdf}
}
► T. Sarmis, A.A. Argyros, M.I.A. Lourakis and K. Hatzopoulos, "Robust and efficient event detection for the monitoring of automated processes", In International conference on visual information engineering (VIE 2006), pp. 454-459, Bangalore, India, September 2006. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: We present a new approach for the detection of events in image sequences. Our method relies on a number of logical sensors that can be defined over specific regions of interest in the viewed scene. These sensors measure time varying image properties that can be attributed to primitive events of interest. Thus, the logical sensors can be viewed as a means to transform image data to a set of symbols that can assist event detection and activities interpretation. On top of these elementary sensors, temporal and logical aggregation mechanisms are used to define hierarchies of progressively more complex sensors, able to detect events having more complex semantics. Finally, scenario verification mechanisms are employed to achieve process monitoring, by checking whether events occur according to a predetermined order. The proposed framework has been tested and validated in an application involving monitoring of automated processes. The obtained results demonstrate that the proposed approach, despite its simplicity, provides a promising framework for vision based event detection in the context of such applications.
BibTeX:
@inproceedings{SarmisArgyrosLourakisEtAl2006a,
  author = {Sarmis, Thomas and Argyros, Antonis A and Lourakis, Manolis I A and Hatzopoulos, Kostas},
  title = {Robust and efficient event detection for the monitoring of automated processes},
  booktitle = {International conference on visual information engineering (VIE 2006)},
  year = {2006},
  month = {September},
  pages = {454--459},
  address = {Bangalore, India},
  url = {http://users.ics.forth.gr/ argyros/res_multisens.html},
  projects =  {MULTISENS},
  doi = {10.1049/cp:20060573},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2006_09_vie06_vbls.pdf}
}
► A.A. Argyros and M.I.A. Lourakis, "Binocular Hand Tracking and Reconstruction Based on 2D Shape Matching", In IEEE International Conference on Pattern Recognition (ICPR 2006), IEEE, pp. 207-210, Hong Kong, August 2006. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: This paper presents a method for real-time 3D hand tracking in images acquired by a calibrated, possibly moving stereoscopic rig. The proposed method consists of a collection of techniques that enable the modeling and detection of hands, their temporal association in image sequences, the establishment of hand correspondences between stereo images and the 3D reconstruction of their contours. Building upon our previous research on color-based, 2D skin-color tracking, the 3D hand tracker is developed through the coupling of the results of two 2D skin-color trackers that run independently on the two video streams acquired by a stereoscopic system. The proposed method runs in real time on a conventional Pentium 4 processor when operating on 320times240 images. Representative experimental results are also presented
BibTeX:
@inproceedings{ArgyrosLourakis2006b,
  author = {Argyros, Antonis A and Lourakis, Manolis I A},
  title = {Binocular Hand Tracking and Reconstruction Based on 2D Shape Matching},
  booktitle = {IEEE International Conference on Pattern Recognition (ICPR 2006)},
  publisher = {IEEE},
  year = {2006},
  month = {August},
  volume = {1},
  pages = {207--210},
  address = {Hong Kong},
  url = {http://users.ics.forth.gr/ argyros/res_colortracking.html},
  projects =  {ACTIPRET,MUSCLE},
  doi = {10.1109/ICPR.2006.327},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2006_08_icpr_3dfht.pdf}
}
► M.I.A. Lourakis and A.A. Argyros, "Chaining Planar Homographies for Fast and Reliable 3D Plane Tracking", In IEEE International Conference on Pattern Recognition (ICPR 2006), IEEE, pp. 582-586, Hong Kong, August 2006. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: This paper addresses the problem of tracking a 3D plane over a sequence of images acquired by a free moving camera, a task that is of central importance to a wide variety of vision tasks. A feature-based method is proposed which given a triplet of consecutive images and a plane homography between the first two of them, estimates the homography induced by the same plane between the second and third images, without requiring the plane to be segmented from the rest of the scene. Thus, the proposed method operates by "chaining" (i.e. propagating) across frames the image-to-image homographies due to some 3D plane. The chaining operation represents projective space using a "plane + parallax" decomposition, which permits the combination of constraints arising from all available point matches, regardless of whether they actually lie on the tracked 3D plane or not. Experimental results are also provided
BibTeX:
@inproceedings{LourakisArgyros2006a,
  author = {Lourakis, Manolis I A and Argyros, Antonis A},
  title = {Chaining Planar Homographies for Fast and Reliable 3D Plane Tracking},
  booktitle = {IEEE International Conference on Pattern Recognition (ICPR 2006)},
  publisher = {IEEE},
  year = {2006},
  month = {August},
  volume = {1},
  pages = {582--586},
  address = {Hong Kong},
  doi = {10.1109/ICPR.2006.358},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2006_08_icpr_planetrack.pdf}
}
► A.A. Argyros and M.I.A. Lourakis, "Vision-Based Interpretation of Hand Gestures for Remote Control of a Computer Mouse", In European Conference on Computer Vision Workshops (HCI 2006 - ECCVW 2006), Springer, pp. 40-51, Graz, Austria, January 2006. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: This paper presents a vision-based interface for controlling a computer mouse via 2D and 3D hand gestures. The proposed interface builds upon our previous work that permits the detection and tracking of multiple hands that can move freely in the field of view of a potentially moving camera system. Dependable hand tracking, combined with fingertip detection, facilitates the definition of simple and, therefore, robustly interpretable vocabularies of hand gestures that are subsequently used to enable a human operator convey control information to a computer system. Two such vocabularies are defined, implemented and validated. The first one depends only on 2D hand tracking results while the second also makes use of 3D information. As confirmed by several experiments, the proposed interface achieves accurate mouse positioning, smooth cursor movement and reliable recognition of gestures activating button events. Owing to these properties, our interface can be used as a virtual mouse for controlling any Windows application.
BibTeX:
@inproceedings{ArgyrosLourakis2006a,
  author = {Argyros, Antonis A and Lourakis, Manolis I A},
  title = {Vision-Based Interpretation of Hand Gestures for Remote Control of a Computer Mouse},
  booktitle = {European Conference on Computer Vision Workshops (HCI 2006 - ECCVW 2006)},
  publisher = {Springer},
  year = {2006},
  month = {January},
  pages = {40--51},
  address = {Graz, Austria},
  url = {http://users.ics.forth.gr/ argyros/res_virtualmouse.html},
  projects =  {ACTIPRET,MUSCLE},
  doi = {10.1007/11754336_5},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2006_05_hci_virtualmouse.pdf},
  videolink = {https://youtu.be/O9DUsRtgigk}
}
► A.A. Argyros and M.I.A. Lourakis, "Tracking skin-colored objects in real-time", Cutting Edge Robotics, Advanced Robotic Systems International, pp. 77-90, 2005. [Abstract] [BibTeX] [PDF] [URL]
Abstract: We present a methodology for tracking multiple skin-colored objects in a monocular image sequence. The proposed approach encompasses a collection of techniques that allow the modeling, detection and temporal association of skin-colored objects across image sequences. A non-parametric model of skin color is employed. Skin-colored objects are detected with a Bayesian classifier that is bootstrapped with a small set of training data and refined through an off-line iterative training procedure. By using on-line adaptation of skin-color probabilities the classifier is able to cope with considerable illumination changes. Tracking over time is achieved by a novel technique that can handle multiple objects simultaneously. Tracked objects may move in complex trajectories, occlude each other in the field of view of a possibly moving camera and vary in number over time. A prototype implementation of the developed system operates on 320x240 live video in real time (28Hz), running on a conventional Pentium IV processor. Representative experimental results from the application of this prototype to image sequences are also presented.
BibTeX:
@incollection{ArgyrosLourakis2005b,
  author = {Argyros, Antonis A and Lourakis, Manolis I A},
  title = {Tracking skin-colored objects in real-time},
  booktitle = {Cutting Edge Robotics},
  publisher = {Advanced Robotic Systems International},
  year = {2005},
  pages = {77--90},
  file = {C:\Users\argyros\OneDrive - ΙΔΡΥΜΑ ΤΕΧΝΟΛΟΓΙΑΣ ΚΑΙ ΕΡΕΥΝΑΣ\antonis\professional\html\mypapers\005_xx_book_Cutting_Edge_Robotics_Book_2D_tracking.pdf:PDF},
  projects =  {ACTIPRET},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2005_xx_book_Cutting_Edge_Robotics_Book_2D_tracking.pdf}
}
► M.I.A. Lourakis and A.A. Argyros, "Efficient, causal camera tracking in unprepared environments", Computer Vision and Image Understanding, Elsevier, vol. 99, no. 2, pp. 259-290, 2005. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: This paper addresses the problem of tracking the 3D pose of a camera in space, using the images it acquires while moving freely in unmodeled, arbitrary environments. A novel feature-based approach for camera tracking is proposed, intended to facilitate tracking in on-line, time-critical applications such as video see-through augmented reality. In contrast to several existing methods which are designed to operate in a batch, off-line mode, assuming that the whole video sequence to be tracked is available before tracking commences, the proposed method operates on images incrementally. At its core lies a feature-based 3D plane tracking technique, which permits the estimation of the homographies induced by a virtual 3D plane between successive image pairs. Knowledge of these homographies allows the corresponding projection matrices encoding camera motion to be expressed in a common projective frame and, therefore, to be recovered directly, without estimating 3D structure. Projective camera matrices are then upgraded to Euclidean and used for recovering structure, which is in turn employed for refining the projection matrices through local resectioning. The proposed approach is causal, is tolerant to erroneous and missing feature matches, does not require modifications of the environment and has computational requirements that permit a near real-time implementation. Extensive experimental results demonstrating the performance of the approach on several image sequences are included.
BibTeX:
@article{LourakisArgyros2005d,
  author = {Lourakis, Manolis I A and Argyros, Antonis A},
  title = {Efficient, causal camera tracking in unprepared environments},
  journal = {Computer Vision and Image Understanding},
  publisher = {Elsevier},
  year = {2005},
  volume = {99},
  number = {2},
  pages = {259--290},
  url = {http://users.ics.forth.gr/ lourakis/camtrack/},
  projects =  {LIFEPLUS},
  doi = {10.1016/j.cviu.2005.02.001},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2005_xx_journal_cviu_camera_tracking.pdf},
  videolink = {http://users.ics.forth.gr/ argyros/imgvideo/CameraTracker.avi}
}
► M.I.A. Lourakis and A.A. Argyros, "Is Levenberg-Marquardt the Most Efficient Optimization Algorithm for Implementing Bundle Adjustment?", In IEEE International Conference on Computer Vision (ICCV 2005), IEEE, pp. 1526-1531, Beijing, China, October 2005. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: In order to obtain optimal 3D structure and viewing parameter estimates, bundle adjustment is often used as the last step of feature-based structure and motion estimation algorithms. Bundle adjustment involves the formulation of a large scale, yet sparse minimization problem, which is traditionally solved using a sparse variant of the Levenberg-Marquardt optimization algorithm that avoids storing and operating on zero entries. This paper argues that considerable computational benefits can be gained by substituting the sparse Levenberg-Marquardt algorithm in the implementation of bundle adjustment with a sparse variant of Powell's dog leg non-linear least squares technique. Detailed comparative experimental results provide strong evidence supporting this claim
BibTeX:
@inproceedings{LourakisArgyros2005c,
  author = {Lourakis, Manolis I A and Argyros, Antonis A},
  title = {Is Levenberg-Marquardt the Most Efficient Optimization Algorithm for Implementing Bundle Adjustment?},
  booktitle = {IEEE International Conference on Computer Vision (ICCV 2005)},
  publisher = {IEEE},
  year = {2005},
  month = {October},
  volume = {2},
  pages = {1526--1531},
  address = {Beijing, China},
  doi = {10.1109/ICCV.2005.128},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2005_10_iccv_levenberg.pdf}
}
► M.I.A. Lourakis and A.A. Argyros, "Fast trifocal tensor estimation using virtual parallax", In IEEE International Conference on Image Processing (ICIP 2005), IEEE, pp. 169-172, Genoa, Italy, September 2005. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: We present a computationally efficient method for estimating the trifocal tensor corresponding to three images acquired by a freely moving camera. The proposed method represents projective space through a "plane + parallax" decomposition and employs a novel technique for estimating the homographies induced by a virtual 3D plane between successive image pairs. Knowledge of these homographies allows the corresponding camera projection matrices to be expressed in a common projective frame and, therefore, to be recovered directly. The trifocal tensor can then be recovered in a straightforward manner from the estimated projection matrices. Sample experimental results demonstrate that the method performs considerably faster compared to a state of the art method, without a serious loss in accuracy.
BibTeX:
@inproceedings{LourakisArgyros2005b,
  author = {Lourakis, Manolis I A and Argyros, Antonis A},
  title = {Fast trifocal tensor estimation using virtual parallax},
  booktitle = {IEEE International Conference on Image Processing (ICIP 2005)},
  publisher = {IEEE},
  year = {2005},
  month = {September},
  volume = {2},
  pages = {169--172},
  address = {Genoa, Italy},
  doi = {10.1109/ICIP.2005.1529999},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2005_09_icip_tensor.pdf}
}
► A.A. Argyros, K.E. Bekris, S.C. Orphanoudakis and L.E. Kavraki, "Robot Homing by Exploiting Panoramic Vision", Autonomous Robots, Springer, vol. 19, no. 1, pp. 7-25, July 2005. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: We propose a novel, vision-based method for robot homing, the problem of computing a route so that a robot can return to its initial “home” position after the execution of an arbitrary “prior” path. The method assumes that the robot tracks visual features in panoramic views of the environment that it acquires as it moves. By exploiting only angular information regarding the tracked features, a local control strategy moves the robot between two positions, provided that there are at least three features that can be matched in the panoramas acquired at these positions. The strategy is successful when certain geometric constraints on the configuration of the two positions relative to the features are fulfilled. In order to achieve long-range homing, the features’ trajectories are organized in a visual memory during the execution of the “prior” path. When homing is initiated, the robot selects Milestone Positions (MPs) on the “prior” path by exploiting information in its visual memory. The MP selection process aims at picking positions that guarantee the success of the local control strategy between two consecutive MPs. The sequential visit of successive MPs successfully guides the robot even if the visual context in the “home” position is radically different from the visual context at the position where homing was initiated. Experimental results from a prototype implementation of the method demonstrate that homing can be achieved with high accuracy, independent of the distance traveled by the robot. The contribution of this work is that it shows how a complex navigational task such as homing can be accomplished efficiently, robustly and in real-time by exploiting primitive visual cues. Such cues carry implicit information regarding the 3D structure of the environment. Thus, the computation of explicit range information and the existence of a geometric map are not required.
BibTeX:
@article{ArgyrosBekrisOrphanoudakisEtAl2005a,
  author = {Argyros, Antonis A and Bekris, Kostas E. and Orphanoudakis, Stelios C and Kavraki, Lydia E},
  title = {Robot Homing by Exploiting Panoramic Vision},
  journal = {Autonomous Robots},
  publisher = {Springer},
  year = {2005},
  month = {July},
  volume = {19},
  number = {1},
  pages = {7--25},
  url = {http://users.ics.forth.gr/ argyros/res_pan_homing.html},
  doi = {10.1007/s10514-005-0603-7},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2005_xx_journal_ar_homing.pdf}
}
► P.E. Trahanias, W. Burgard, A.A. Argyros, D. Hähnel, H. Baltzakis, P. Pfaff and C. Stachniss, "TOURBOT and WebFAIR: Web-operated mobile robots for tele-presence in populated exhibitions", IEEE Robotics and Automation Magazine, IEEE, vol. 12, no. 2, pp. 77-89, June 2005. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: This paper presents a number of techniques that are needed for realizing Web-operated mobile robots. These techniques include effective map-building capabilities, a method for obstacle avoidance based on a combination of range and visual information, and advanced Web and onboard robot interfaces. In addition to video streams, the system provides high-resolution virtual reality visualizations that also include the people in the vicinity of the robot. This increases the flexibility of the interface and simultaneously allows a user to understand the navigation actions of the robot. The techniques described in this article have been successfully deployed within the EU-funded projects TOURBOT and WebFAIR, which aimed to develop interactive tour-guided robots able to serve Web as well as on-site visitors. Technical developments in the framework of these projects have resulted in robust and reliable systems that have been demonstrated and validated in real-world conditions. Equally important, the system setup time has been drastically reduced, facilitating its porting to new environments.
BibTeX:
@article{TrahaniasBurgardArgyrosEtAl2005a,
  author = {Trahanias, Panos E and Burgard, Wolfram and Argyros, Antonis A and Hähnel, Dirk and Baltzakis, Haris and Pfaff, Patrick and Stachniss, Cyrill},
  title = {TOURBOT and WebFAIR: Web-operated mobile robots for tele-presence in populated exhibitions},
  journal = {IEEE Robotics and Automation Magazine},
  publisher = {IEEE},
  year = {2005},
  month = {June},
  volume = {12},
  number = {2},
  pages = {77--89},
  url = {http://users.ics.forth.gr/ argyros/res_robotsinexhibitions.html},
  projects =  {TOURBOT,WEBFAIR},
  doi = {10.1109/MRA.2005.1458329},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2005_xx_journal_ram_tourbot_webfair.pdf},
  videolink = {http://users.ics.forth.gr/ argyros/imgvideo/TourbotInBrief.mpg}
}
► A.A. Argyros and M.I.A. Lourakis, "Tracking Multiple Colored Blobs with a Moving Camera", In IEEE Computer Vision and Pattern Recognition (CVPR 2005), IEEE, pp. 1178, San Diego, CA, USA, June 2005. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: This paper concerns a method for tracking multiple blobs exhibiting certain color distributions in images acquired by a possibly moving camera. The method encompasses a collection of techniques that enable modeling and detecting the blobs possessing the desired color distribution(s), as well as inferring their temporal association across image sequences. Appropriately colored blobs are detected with a Bayesian classifier, which is bootstrapped with a small set of training data. Then, an online iterative training procedure is employed to refine the classifier using additional training images. Online adaptation of color probabilities is used to enable the classifier to cope with illumination changes. Tracking over time is realized through a novel technique, which can handle multiple colored blobs. Such blobs may move in complex trajectories and occlude each other in the field of view of a possibly moving camera, while their number may vary over time. A prototype implementation of the developed system running on a conventional Pentium IV processor at 2.5 GHz operates on 320×240 live video in real time (30Hz). It is worth pointing out that currently, the cycle time of the tracker is determined by the maximum acquisition frame rate that is supported by our IEEE 1394 camera, rather than the latency introduced by the computational overhead for tracking blobs.
BibTeX:
@inproceedings{ArgyrosLourakis2005a,
  author = {Argyros, Antonis A and Lourakis, Manolis I A},
  title = {Tracking Multiple Colored Blobs with a Moving Camera},
  booktitle = {IEEE Computer Vision and Pattern Recognition (CVPR 2005)},
  publisher = {IEEE},
  year = {2005},
  month = {June},
  volume = {2},
  pages = {1178},
  address = {San Diego, CA, USA},
  url = {http://users.ics.forth.gr/ argyros/res_colortracking.html},
  projects =  {ACTIPRET},
  doi = {10.1109/CVPR.2005.348},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2005_06_vpcvpr_blobtracking.pdf}
}
► M.I.A. Lourakis and A.A. Argyros, "Camera Matchmoving in Unprepared, Unknown Environments", In IEEE Computer Vision and Pattern Recognition (CVPR 2005), IEEE, pp. 1190, San Diego, CA, USA, June 2005. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: Camera matchmoving is an application involving synthesis of real scenes and artificial objects, in which the goal is to insert computer-generated graphical 3D objects into live-action footage depicting unmodeled, arbitrary scenes. This work addresses the problem of tracking the 3D motion of a camera in space, using only the images it acquires while moving freely in unmodeled, arbitrary environments. A novel feature-based method for camera tracking has been developed, intended to facilitate tracking in online, time-critical applications such as video see-through augmented reality and vision-based control. In contrast to several existing techniques, which are designed to operate in a batch, offline mode, assuming that the whole video sequence to be tracked is available before tracking commences, our method operates on images incrementally, as they are being acquired.
BibTeX:
@inproceedings{LourakisArgyros2005a,
  author = {Lourakis, Manolis I A and Argyros, Antonis A},
  title = {Camera Matchmoving in Unprepared, Unknown Environments},
  booktitle = {IEEE Computer Vision and Pattern Recognition (CVPR 2005)},
  publisher = {IEEE},
  year = {2005},
  month = {June},
  volume = {2},
  pages = {1190},
  address = {San Diego, CA, USA},
  url = {http://users.ics.forth.gr/ lourakis/camtrack/},
  projects =  {LIFEPLUS},
  doi = {10.1109/CVPR.2005.96},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2005_06_vpcvpr_matchmoving.pdf}
}
► A.A. Argyros and M.I.A. Lourakis, "Three-dimensional tracking of multiple skin-colored regions by a moving stereoscopic system", Applied Optics, [New York: Optical Society of America], 1962-, vol. 43, no. 2, pp. 366-378, 2004. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: A system that performs three-dimensional (3D) tracking of multiple skin-colored regions (SCRs) in images acquired by a calibrated, possibly moving stereoscopic rig is described. The system consists of a collection of techniques that permit the modeling and detection of SCRs, the determination of their temporal association in monocular image sequences, the establishment of their correspondence between stereo images, and the extraction of their 3D positions in a world-centered coordinate system. The development of these techniques has been motivated by the need for robust, near-real-time tracking performance. SCRs are detected by use of a Bayesian classifier that is trained with the aid of a novel technique. More specifically, the classifier is bootstrapped with a small set of training data. Then, as new images are being processed, an iterative training procedure is employed to refine the classifier. Furthermore, a technique is proposed to enable the classifier to cope with changes in illumination. Tracking of SCRs in time as well as matching of SCRs in the images of the employed stereo rig is performed through computationally inexpensive and robust techniques. One of the main characteristics of the skin-colored region tracker (SCRT) instrument is its ability to report the 3D positions of SCRs in a world-centered coordinate system by employing a possibly moving stereo rig with independently verging CCD cameras. The system operates on images of dimensions 640x480 pixels at a rate of 13 Hz on a conventional Pentium 4 processor at 1.8 GHz. Representative experimental results from the application of the SCRT to image sequences are also provided.
BibTeX:
@article{ArgyrosLourakis2004b,
  author = {Argyros, Antonis A and Lourakis, Manolis I A},
  title = {Three-dimensional tracking of multiple skin-colored regions by a moving stereoscopic system},
  journal = {Applied Optics},
  publisher = {[New York: Optical Society of America], 1962-},
  year = {2004},
  volume = {43},
  number = {2},
  pages = {366--378},
  url = {http://users.ics.forth.gr/ argyros/res_colortracking.html},
  projects =  {ACTIPRET},
  doi = {10.1364/AO.43.000366},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2004_04_journal_aoip_vol43_no2_pp366-378_3d_skin_tracking.pdf}
}
► M.I.A. Lourakis and A.A. Argyros, "The Design and Implementation of a Generic Sparse Bundle Adjustment Software Package Based on the Levenberg-Marquardt Algorithm", FORTH-ICS, TR-340, 2004. [Abstract] [BibTeX] [PDF] [URL]
Abstract: Bundle adjustment using the Levenberg-Marquardt minimization algorithm is almost invariably used as the last step of every feature-based structure and motion estimation vision algorithm to obtain optimal 3D structure and viewing parameter estimates. However, due to the large number of unknowns contributing to the minimized reprojection error, a general purpose implementation of the Levenberg-Marquardt algorithm incurs high computational costs when applied to the problem of bundle adjustment. Fortunately, the lack of interaction among parameters for different 3D points and cameras in multiple view reconstruction results in the under-lying normal equations exhibiting a sparse block structure, which can be exploited to gain considerable computational benefits. This paper presents the design and explains the use of sba, a publicly available C/C++ software package for generic bundle adjustment based on the sparse Levenberg-Marquardt algorithm.
BibTeX:
@techreport{LourakisArgyros2004b,
  author = {Lourakis, Manolis I A and Argyros, Antonis A},
  title = {The Design and Implementation of a Generic Sparse Bundle Adjustment Software Package Based on the Levenberg-Marquardt Algorithm},
  school = {FORTH-ICS},
  year = {2004},
  number = {TR-340},
  url = {http://users.ics.forth.gr/ lourakis/sba/},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2004_08_tr340_forth_sba.pdf}
}
► A.A. Argyros, D.P. Tsakiris and C. Groyer, "Biomimetic centering behavior [mobile robots with panoramic sensors]", IEEE Robotics and Automation Magazine, IEEE, vol. 11, no. 4, pp. 21-30, December 2004. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: A reactive robotic centering behavior based on panoramic vision is presented. It is inspired by the way insects exploit visual information in analogous navigation tasks. By employing a panoramic camera, the development of the centering behavior is simplified both from a theoretical and from an implementation point of view. The proposed method relies on the extraction of primitive visual information from appropriately selected areas of a panoramic visual field and its direct use in the control law. Experimental results from an implementation of this method on a robotic platform demonstrate a centering behavior which can be achieved in real-time and with high accuracy. The proposed technique circumvents the need to address complex problems of 3D structure estimation and the resulting control laws were shown to possess the required stability properties.
BibTeX:
@article{ArgyrosTsakirisGroyer2004a,
  author = {Argyros, Antonis A and Tsakiris, Dimitris P and Groyer, Cedric},
  title = {Biomimetic centering behavior [mobile robots with panoramic sensors]},
  journal = {IEEE Robotics and Automation Magazine},
  publisher = {IEEE},
  year = {2004},
  month = {December},
  volume = {11},
  number = {4},
  pages = {21--30},
  url = {http://users.ics.forth.gr/ argyros/res_biomimeticcentering.html},
  doi = {10.1109/MRA.2004.1371612},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2004_12_journal_ram_biomimetic_centering.pdf},
  videolink = {http://users.ics.forth.gr/ argyros/imgvideo/CorridorFollowing.avi}
}
► M.I.A. Lourakis, A.A. Argyros and K. Marias, "A graph-based approach to corner matching using mutual information as a local similarity measure", In IEEE International Conference on Pattern Recognition (ICPR 2004), IEEE, pp. 827-830, Cambridge, UK, August 2004. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: Corner matching constitutes a fundamental vision problem that serves as a building block of several important applications. The common approach to dealing with this problem starts by ranking potential matches according to their affinity, which is assessed with the aid of window-based intensity similarity measures. Then, actual matches are established by optimizing global criteria involving all potential matches. This paper puts forward a novel approach for solving the corner matching problem that uses mutual information as a window similarity measure, combined with graph matching techniques for determining a matching of corners that is globally optimal. Experimental results illustrate the effectiveness of the approach.
BibTeX:
@inproceedings{LourakisArgyrosMarias2004a,
  author = {Lourakis, Manolis I A and Argyros, Antonis A and Marias, Kostas},
  title = {A graph-based approach to corner matching using mutual information as a local similarity measure},
  booktitle = {IEEE International Conference on Pattern Recognition (ICPR 2004)},
  publisher = {IEEE},
  year = {2004},
  month = {August},
  volume = {2},
  pages = {827--830},
  address = {Cambridge, UK},
  doi = {10.1109/ICPR.2004.1334386},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2004_08_icpr_corner_matching.pdf}
}
► M.I.A. Lourakis and A.A. Argyros, "Vision-based camera motion recovery for augmented reality", In Computer Graphics International (CGI 2004), pp. 569-576, Hersonissos, Crete, Greece, June 2004. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: We address the problem of tracking the 3D position and orientation of a camera, using the images it acquires while moving freely in unmodeled, arbitrary environments. This task has a broad spectrum of useful applications in domains such as augmented reality and video post production. Most of the existing methods for vision-based camera tracking are designed to operate in a batch, off-line mode, assuming that the whole video sequence to be tracked is available before tracking commences. Typically, such methods operate noncausally, processing video frames backwards and forwards in time as they see fit. Furthermore, they resort to optimization in very high dimensional spaces, a process that is computationally intensive. For these reasons, batch methods are inapplicable to tracking in online, time-critical applications such as video see-through augmented reality. This paper puts forward a novel feature-based approach for camera tracking. The proposed approach operates on images continuously as they are acquired, has realistic computational requirements and does not require modifications of the environment. Sample experimental results demonstrating the feasibility of the approach on video images are also provided
BibTeX:
@inproceedings{LourakisArgyros2004a,
  author = {Lourakis, Manolis I A and Argyros, Antonis A},
  title = {Vision-based camera motion recovery for augmented reality},
  booktitle = {Computer Graphics International (CGI 2004)},
  year = {2004},
  month = {June},
  pages = {569--576},
  address = {Hersonissos, Crete, Greece},
  url = {http://users.ics.forth.gr/ lourakis/camtrack/},
  projects =  {LIFEPLUS},
  doi = {10.1109/CGI.2004.1309266},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2004_06_cgi_camera_tracking.pdf}
}
► K.E. Bekris, A.A. Argyros and L.E. Kavraki, "Angle-based methods for mobile robot navigation: reaching the entire plane", In IEEE International Conference on Robotics and Automation (ICRA 2004), IEEE, pp. 2373-2378, Barcelona, Spain, April 2004. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: Popular approaches for mobile robot navigation involve range information and metric maps of the workspace. For many sensors, however, such as cameras and wireless hardware, the angle between two features or beacons is easier to measure. With these sensors' features in mind, we initially present a control law, which allows a robot with an omni-directional sensor to reach a subset of the plane by monitoring the angles of only three landmarks. By analyzing the law's properties, a second law has been developed that reaches the complementary set of points. The two methods are then combined in a path planning framework that reaches any possible goal configuration in a planar obstacle-free workspace with three landmarks. The proposed framework could be used together with other techniques, such as obstacle avoidance and topological maps to improve the efficiency of autonomous navigation. Experiments have been conducted on a robotic platform using a panoramic camera that exhibits the effectiveness and accuracy of the proposed techniques. This work provides evidence that navigational tasks can be performed using only a small number of primitive sensor cues and without the explicit computation of range information.
BibTeX:
@inproceedings{BekrisArgyrosKavraki2004a,
  author = {Bekris, Kostas E and Argyros, Antonis A and Kavraki, Lydia E.},
  title = {Angle-based methods for mobile robot navigation: reaching the entire plane},
  booktitle = {IEEE International Conference on Robotics and Automation (ICRA 2004)},
  publisher = {IEEE},
  year = {2004},
  month = {April},
  volume = {3},
  pages = {2373--2378},
  address = {Barcelona, Spain},
  url = {http://users.ics.forth.gr/ argyros/res_anglebasednavigation.html},
  doi = {10.1109/ROBOT.2004.1307416},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2004_04_icra_angle_based_navigation.pdf}
}
► A.A. Argyros and M.I.A. Lourakis, "Real-time tracking of multiple skin-colored objects with a possibly moving camera", In European Conference on Computer Vision (ECCV 2004), Springer, pp. 368-379, Prague, Czech Republic, January 2004. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: This paper presents a method for tracking multiple skin-colored objects in images acquired by a possibly moving camera. The proposed method encompasses a collection of techniques that enable the modeling and detection of skin-colored objects as well as their temporal association in image sequences. Skin-colored objects are detected with a Bayesian classifier which is bootstrapped with a small set of training data. Then, an off-line iterative training procedure is employed to refine the classifier using additional training images. On-line adaptation of skin-color probabilities is used to enable the classifier to cope with illumination changes. Tracking over time is realized through a novel technique which can handle multiple skin-colored objects. Such objects may move in complex trajectories and occlude each other in the field of view of a possibly moving camera. Moreover, the number of tracked objects may vary in time. A prototype implementation of the developed system operates on 320x240 live video in real time (28Hz) on a conventional Pentium 4 processor. Representative experimental results from the application of this prototype to image sequences are also provided.
BibTeX:
@inproceedings{ArgyrosLourakis2004a,
  author = {Argyros, Antonis A and Lourakis, Manolis I A},
  title = {Real-time tracking of multiple skin-colored objects with a possibly moving camera},
  booktitle = {European Conference on Computer Vision (ECCV 2004)},
  publisher = {Springer},
  year = {2004},
  month = {January},
  pages = {368--379},
  address = {Prague, Czech Republic},
  url = {http://users.ics.forth.gr/ argyros/res_colortracking.html},
  projects =  {ACTIPRET},
  doi = {10.1007/978-3-540-24672-5_29},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2004_05_eccv_hand_tracking_2d.pdf},
  videolink = {https://youtu.be/m4qv9rK8k9s}
}
► S.C. Orphanoudakis, A.A. Argyros and M. Vincze, "Towards a cognitive vision methodology: understanding and interpreting activities of experts", ERCIM News, no. 53, 2003. [BibTeX] [PDF] [URL] [VIDEO]
BibTeX:
@periodical{OrphanoudakisArgyrosVincze2003a,
  author = {Orphanoudakis, Stelios C and Argyros, Antonis A and Vincze, Markus},
  title = {Towards a cognitive vision methodology: understanding and interpreting activities of experts},
  journal = {ERCIM News},
  year = {2003},
  number = {53},
  url = {http://users.ics.forth.gr/ argyros/res_colortracking.html},
  projects =  {ACTIPRET},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2003_04_report_ercim_actipret.pdf},
  videolink = {http://users.ics.forth.gr/ argyros/imgvideo/ActipretVideo.mpg}
}
► K. Bekris, A.A. Argyros and L. Kavraki, "Angle-Based Methods for Mobile Robot Navigation: Reaching the Entire Plane", Rice University, TR03-426, 2003. [BibTeX] [DOI] [URL] [VIDEO]
BibTeX:
@techreport{BekrisArgyrosKavraki2003a,
  author = {Bekris, Kostas and Argyros, Antonis A and Kavraki, Lydia},
  title = {Angle-Based Methods for Mobile Robot Navigation: Reaching the Entire Plane},
  school = {Rice University},
  year = {2003},
  number = {TR03-426},
  address = {Houston, Texas, USA},
  url = {http://users.ics.forth.gr/ argyros/res_anglebasednavigation.html},
  doi = {http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.30.2482\&rep=rep1\&type=pdf},
  videolink = {http://users.ics.forth.gr/ argyros/imgvideo/snapshot.mpg}
}
► M.I.A. Lourakis and A.A. Argyros, "Efficient 3D Camera Matchmoving Using Markerless, Segmentation-Free Plane Tracking", FORTH-ICS, TR-324, 2003. [Abstract] [BibTeX] [PDF] [URL]
Abstract: We address the problem of tracking the position and orientation of a camera in 3D space, using the images it acquires while moving freely in unmodeled, arbitrary environments. This task has a broad spectrum of useful applications in domains such as augmented reality and video post production. Most of the existing methods for camera tracking are designed to operate in a batch, off-line mode, assuming that the whole video sequence to be tracked is available before tracking commences. Typically, such methods operate non-causally, processing video frames backwards and forwards in time as they see fit. Furthermore, they resort to optimization in very high dimensional spaces, a process that is computationally intensive. For these reasons, batch methods are inapplicable to tracking in on-line, time-critical applications such as video see-through augmented reality. This paper puts forward a novel feature-based approach for camera tracking. The proposed approach operates continuously as images are acquired, has realistic computational requirements and does not require modifications of the environment. At its core lies a novel, feature-based 3D plane tracking technique, which permits the estimation of the homographies induced by a virtual 3D plane between successive image pairs. Knowledge of these homographies allows the corresponding projection matrices encoding camera motion to be expressed in a common projective frame and, therefore, to be recovered directly. Projective camera matrices are then upgraded to Euclidean and used for recovering 3D structure, which is in turn employed for refining the projection matrices through local bundle adjustment. Sample experimental results demonstrating the feasibility of the approach on several image sequences are also provided.
BibTeX:
@techreport{LourakisArgyros2003a,
  author = {Lourakis, Manolis I A and Argyros, Antonis A},
  title = {Efficient 3D Camera Matchmoving Using Markerless, Segmentation-Free Plane Tracking},
  school = {FORTH-ICS},
  year = {2003},
  number = {TR-324},
  url = {http://users.ics.forth.gr/ lourakis/camtrack/},
  projects =  {LIFEPLUS},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2003_09_tr324_forth_camera_tracking.pdf}
}
► D.P. Tsakiris, A.A. Argyros and C. Groyer, "Experiments in Corridor Following with Nonholonomic Mobile Robots Equipped with Panoramic Cameras", Institute of Computer Science - FORTH, TR-318, 2003. [BibTeX] [URL] [VIDEO]
BibTeX:
@techreport{TsakirisArgyrosGroyer2003a,
  author = {Tsakiris, Dimitris P and Argyros, Antonis A and Groyer, Cedric},
  title = {Experiments in Corridor Following with Nonholonomic Mobile Robots Equipped with Panoramic Cameras},
  school = {Institute of Computer Science - FORTH},
  year = {2003},
  number = {TR-318},
  url = {http://users.ics.forth.gr/ argyros/res_biomimeticcentering.html},
  videolink = {http://users.ics.forth.gr/ argyros/imgvideo/CorridorFollowing.avi}
}
► H. Baltzakis, A.A. Argyros and P.E. Trahanias, "Fusion of laser and visual data for robot motion planning and collision avoidance", Machine Vision Applications, Springer, vol. 15, no. 2, pp. 92-100, December 2003. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: In this paper, a method for inferring scene structure information based on both laser and visual data is proposed. Common laser scanners employed in contemporary robotic systems provide accurate range measurements, but only in 2D slices of the environment. On the other hand, vision is capable of providing dense 3D information of the environment. The proposed fusion scheme combines the accuracy of laser sensors with the broad visual fields of cameras toward extracting accurate scene structure information. Data fusion is achieved by validating 3D structure assumptions formed according to 2D range scans of the environment, through the exploitation of visual information. The proposed methodology is applied to robot motion planning and collision avoidance tasks by using a suitably modified version of the vector field histogram algorithm. Experimental results confirm the effectiveness of the proposed methodology.
BibTeX:
@article{BaltzakisArgyrosTrahanias2003a,
  author = {Baltzakis, Haris and Argyros, Antonis A and Trahanias, Panos E},
  title = {Fusion of laser and visual data for robot motion planning and collision avoidance},
  journal = {Machine Vision Applications},
  publisher = {Springer},
  year = {2003},
  month = {December},
  volume = {15},
  number = {2},
  pages = {92--100},
  url = {http://users.ics.forth.gr/ argyros},
  doi = {10.1007/s00138-003-0133-2},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2003_10_journal_mva_vol15_pp92-100_fusion_laser_vision.pdf}
}
► W. Burgard, P.E. Trahanias, D. Hähnel, M. Moors, D. Schulz, H. Baltzakis and A.A. Argyros, "Tele-Presence in Populated Exhibitions Through Web-Operated Mobile Robots", Autonomous Robots, Springer, vol. 15, no. 3, pp. 299-316, November 2003. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: This paper presents techniques that facilitate mobile robots to be deployed as interactive agents in populated environments such as museum exhibitions or trade shows. The mobile robots can be tele-operated over the Internet and, this way, provide remote access to distant users. Throughout this paper we describe several key techniques that have been developed in this context. To support safe and reliable robot navigation, techniques for environment mapping, robot localization, obstacle detection and people-tracking have been developed. To support the interaction of both web and on-site visitors with the robot and its environment, appropriate software and hardware interfaces have been employed. By using advanced navigation capabilities and appropriate authoring tools, the time required for installing a robotic tour-guide in a museum or a trade fair has been drastically reduced. The developed robotic systems have been thoroughly tested and validated in the real-world conditions offered in the premises of various sites. Such demonstrations ascertain the functionality of the employed techniques, establish the reliability of the complete systems, and provide useful evidence regarding the acceptance of tele-operated robotic tour-guides by the broader public.
BibTeX:
@article{BurgardTrahaniasHaehnelEtAl2003a,
  author = {Burgard, Wolfram and Trahanias, Panos E and Hähnel, Dirk and Moors, Mark and Schulz, Dirk and Baltzakis, Haris and Argyros, Antonis A},
  title = {Tele-Presence in Populated Exhibitions Through Web-Operated Mobile Robots},
  journal = {Autonomous Robots},
  publisher = {Springer},
  year = {2003},
  month = {November},
  volume = {15},
  number = {3},
  pages = {299--316},
  url = {http://users.ics.forth.gr/ argyros/res_robotsinexhibitions.html},
  projects =  {WEBFAIR,TOURBOT},
  doi = {10.1023/A:1026272605502},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2003_xx_journal_ar_vol15_no2_pp299-316_robots_in_exhibitions.pdf}
}
► P.E. Trahanias, W. Burgard, D. Haehnel, M. Moors, D. Schulz, H. Baltzakis and A.A. Argyros, "Interactive tele-presence in exhibitions through web-operated robots", In International Conference on Advanced Robotics (ICAR 2003), invited session on Robotics and Art, pp. 1253-1258, Coimbra, Portugal, June 2003. [Abstract] [BibTeX] [PDF] [URL]
Abstract: The current paper presents techniques that facilitate mobile robots to be deployed as interactive agents in populated environments, such as museum exhibitions or trade shows. The mobile robots can be tele-operated over the Internet and this way provide remote access to distant users. Throughout this paper we describe several key techniques that have been developed in the relevant projects. They include robust mapping and localization, people-tracking and advanced visualizations for Web users. The developed robotic systems have been installed and operated in the premises of various sites. Use of the above techniques, as well as appropriate authoring tools, has resulted in drastic reduction in the installation times. Additionally, the systems were thoroughly tested and validated in real-world conditions. Such demonstrations ascertain the functionality and reliability of our methods and provide evidence as of the operation of the complete systems.
BibTeX:
@inproceedings{TrahaniasBurgardHaehnelEtAl2003a,
  author = {Trahanias, Panos E and Burgard, Wolfram and Haehnel, Dirk and Moors, Mark and Schulz, Dirk and Baltzakis, Haris and Argyros, Antonis A},
  title = {Interactive tele-presence in exhibitions through web-operated robots},
  booktitle = {International Conference on Advanced Robotics (ICAR 2003), invited session on Robotics and Art},
  year = {2003},
  month = {June},
  pages = {1253--1258},
  address = {Coimbra, Portugal},
  url = {http://users.ics.forth.gr/ argyros/res_robotsinexhibitions.html},
  projects =  {WEBFAIR,TOURBOT},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2003_06_icar_exhibitions.pdf}
}
► M.I.A. Lourakis, S.V. Tzurbakis, A.A. Argyros and S.C. Orphanoudakis, "Feature transfer and matching in disparate stereo views through the use of plane homographies", IEEE Transactions on Pattern Analysis and Machine Intelligence, IEEE, vol. 25, no. 2, pp. 271-276, February 2003. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: Many vision tasks rely upon the identification of sets of corresponding features among different images. This paper presents a method that, given some corresponding features in two stereo images, matches them with features extracted from a second stereo pair captured from a distant viewpoint. The proposed method is based on the assumption that the viewed scene contains two planar surfaces and exploits geometric constraints that are imposed by the existence of these planes to first transfer and then match image features between the two stereo pairs. The resulting scheme handles point and line features in a unified manner and is capable of successfully matching features extracted from stereo pairs that are acquired from considerably different viewpoints. Experimental results are presented, which demonstrate that the performance of the proposed method compares favorably to that of epipolar and tensor-based approaches.
BibTeX:
@article{LourakisTzurbakisArgyrosEtAl2003a,
  author = {Lourakis, Manolis I A and Tzurbakis, Stavros V and Argyros, Antonis A and Orphanoudakis, Stelios C},
  title = {Feature transfer and matching in disparate stereo views through the use of plane homographies},
  journal = {IEEE Transactions on Pattern Analysis and Machine Intelligence},
  publisher = {IEEE},
  year = {2003},
  month = {February},
  volume = {25},
  number = {2},
  pages = {271--276},
  doi = {10.1109/TPAMI.2003.1177157},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2003_02_journal_pami_feature_matching.pdf}
}
► A.A. Argyros, P. Georgiadis, P.E. Trahanias and D.P. Tsakiris, "Semi-autonomous navigation of a robotic wheelchair", Journal of Intelligent and Robotic Systems, Kluwer Academic Publishers, vol. 34, no. 3, pp. 315-329, 2002. [Abstract] [BibTeX] [DOI] [URL] [VIDEO]
Abstract: Abstract. The present work considers the development of a wheelchair for people with special needs, which is capable of navigating semi-autonomously within its workspace. This system is expected to prove useful to people with impaired mobility and limited fine motor control of the upper extremities. Among the implemented behaviors of this robotic system are the avoidance of obstacles, the motion in the middle of the free space and the following of a moving target specified by the user (e.g., a person walking in front of the wheelchair). The wheelchair is equipped with sonars, which are used for distance measurement in preselected critical directions, and with a panoramic camera with a 360 degree field of view, which is used for following a moving target. After suitably processing the color sequence of the panoramic images using the color histogram of the desired target, the orientation of the target with respect to the wheelchair is determined, while its distance is determined by the sonars. The motion control laws developed for the system use the sensory data and take into account the non-holonomic kinematic constraints of the wheelchair, in order to guarantee certain desired features of the closed-loop system, such as stability. Moreover, they are as simplified as possible to minimize implementation requirements. An experimental prototype has been developed at ICS—FORTH, based on a commercially-available wheelchair. The sensors, the computing power and the electronics needed for the implementation of the navigation behaviors and of the user interfaces (touch screen, voice commands) were developed as add-on modules and integrated with the wheelchair.
BibTeX:
@article{ArgyrosGeorgiadisTrahaniasEtAl2002a,
  author = {Argyros, Antonis A and Georgiadis, Pantelis and Trahanias, Panos E and Tsakiris, Dimitris P},
  title = {Semi-autonomous navigation of a robotic wheelchair},
  journal = {Journal of Intelligent and Robotic Systems},
  publisher = {Kluwer Academic Publishers},
  year = {2002},
  volume = {34},
  number = {3},
  pages = {315--329},
  url = {http://users.ics.forth.gr/ argyros/res_pan_track.html},
  doi = {10.1023/A:1016371922451},
  videolink = {http://users.ics.forth.gr/ argyros/imgvideo/ChairFollowsPerson.mpg}
}
► K. Bekris, K. Hatzopoulos, G. Kazazakis, G. Kontolemakis, M. Masvoula, N. Tsivourakis, A.A. Argyros and P. Trahanias, "PYTHEAS: an integrated robotic system with autonomous navigation capabilities", Image Processing and Applications, Image Processing & Communications Journal, Special issue on Intelligent Sensing, De Gruyter publications, vol. 8, no. 2, pp. 81-92, 2002. [Abstract] [BibTeX] [PDF]
Abstract: In this paper we present PYTHEAS, an integrated robotic software system that supports autonomous navigation capabilities. These include localization, workspace mapping, path planning and tracking, and obstacle avoidance. PYTHEAS enables mapping of an unknown indoor environment by exploiting sensory information extracted from a laser scanner. Based on this acquired environment representation, the system is able to navigate autonomously in the mapped workspace, avoiding at the same time dynamic obstacles, such as moving persons or other objects. The developed competences are coupled in an integrated system, which can be controlled through a user-friendly interface over the web. Experimental results demonstrate the ability of the developed system to map complicated environments and support navigation in dynamic worlds.
BibTeX:
@article{BekrisHatzopoulosKazazakisEtAl2002a,
  author = {Bekris, Kostas and Hatzopoulos, Kostas and Kazazakis, Giorgos and Kontolemakis, Giorgos and Masvoula, M and Tsivourakis, Nikos and Argyros, Antonis A and Trahanias, Panos},
  title = {PYTHEAS: an integrated robotic system with autonomous navigation capabilities},
  journal = {Image Processing and Applications, Image Processing & Communications Journal, Special issue on Intelligent Sensing},
  publisher = {De Gruyter publications},
  year = {2002},
  volume = {8},
  number = {2},
  pages = {81--92},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2002_xx_journal_pcj_vol8_no2_pp81-92_pytheas.pdf}
}
► M.I.A. Lourakis, A.A. Argyros and S.C. Orphanoudakis, "Detecting Planes In An Uncalibrated Image Pair.", In British Machine Vision Conference (BMVC 2002), BMVA, pp. 587-596, Cardiff, UK, 2002. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: Plane detection is a prerequisite to a wide variety of vision tasks. This paper proposes a novel method that exploits results from projective geometry to automatically detect planes using two images. Using a set of point and line features that have been matched between images, the method exploits the fact that every pair of a 3D line and a 3D point defines a plane and utilizes an iterative voting scheme for identifying coplanar subsets of the employed feature set. The method does not require camera calibration, circumvents the 3D reconstruction problem is robust to the existence of mismatched features and is applicable either to stereo or motion sequence images. Sample results from the application of the proposed method to real imagery are also provided.
BibTeX:
@inproceedings{LourakisArgyrosOrphanoudakis2002a,
  author = {Lourakis, Manolis I A and Argyros, Antonis A and Orphanoudakis, Stelios C},
  title = {Detecting Planes In An Uncalibrated Image Pair.},
  booktitle = {British Machine Vision Conference (BMVC 2002)},
  publisher = {BMVA},
  year = {2002},
  pages = {587--596},
  address = {Cardiff, UK},
  doi = {10.5244/C.16.57},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2002_09_bmvc_plane_detection.pdf}
}
► W. Burgard, P. Trahanias, D. Hähnel, M. Moors, D. Schulz, H. Baltzakis and A.A. Argyros, "TOURBOT and WebFAIR: Web-operated mobile robots for tele-presence in populated exhibitions", In IEEE/RSJ International Conference on Intelligent Robots and Systems Workshops (IROSW 2002), IEEE, pp. 1-10, Lausanne, Switzerland, October 2002. [Abstract] [BibTeX] [PDF] [URL] [VIDEO]
Abstract: The current paper presents techniques that facilitate mobile robots to be deployed as interactive agents in populated environments, such as museum exhibitions or trade shows. The mobile robots can be tele-operated over the Internet and this way provide remote access to distant users. Throughout this paper we describe several key techniques that have been developed in the relevant projects. They include robust mapping and localization, people-tracking and advanced visualizations for Web users. The developed robotic systems have been installed and operated in the premises of various sites. Use of the above techniques, as well as appropriate authoring tools, has resulted in drastic reduction in the installation times. Additionally, the systems were thoroughly tested and validated in real-world conditions. Such demonstrations ascertain the functionality and reliability of our methods and provide evidence as of the operation of the complete systems.
BibTeX:
@inproceedings{BurgardTrahaniasHaehnelEtAl2002a,
  author = {Burgard, Wolfram and Trahanias, Panos and Hähnel, Dirk and Moors, Mark and Schulz, Dirk and Baltzakis, Haris and Argyros, Antonis A},
  title = {TOURBOT and WebFAIR: Web-operated mobile robots for tele-presence in populated exhibitions},
  booktitle = {IEEE/RSJ International Conference on Intelligent Robots and Systems Workshops (IROSW 2002)},
  publisher = {IEEE},
  year = {2002},
  month = {October},
  pages = {1--10},
  address = {Lausanne, Switzerland},
  url = {http://users.ics.forth.gr/ argyros/res_robotsinexhibitions.html},
  projects =  {WEBFAIR,TOURBOT},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2002_10_iros_exhibitions.pdf},
  videolink = {http://users.ics.forth.gr/ argyros/imgvideo/TourbotInBrief.mpg}
}
► G.D. Kazazakis and A.A. Argyros, "Fast positioning of limited-visibility guards for the inspection of 2D workspaces", In IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2002), IEEE, pp. 2843 - 2848, Lausanne, Switzerland, October 2002. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: This paper presents a novel method for deciding the locations of "guards" required to visually inspect a given 2D workspace. The decided guard positions can then be used as control points in the path of a mobile robot that autonomously inspects a workspace. It is assumed that each of the guards (or the mobile robot that visits the guard positions in some order) is equipped with a panoramic camera of 360 degrees field of view. However, the camera has limited visibility, in the sense that it can observe with sufficient detail objects that are not further than a predefined visibility range. The method seeks to efficiently produce solutions that contain the smaller possible number of guards. Experimental results demonstrate that the proposed method is computationally efficient and that, although suboptimal, decides a small number of guards.
BibTeX:
@inproceedings{KazazakisArgyros2002a,
  author = {Kazazakis, Giorgos D. and Argyros, Antonis A},
  title = {Fast positioning of limited-visibility guards for the inspection of 2D workspaces},
  booktitle = {IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2002)},
  publisher = {IEEE},
  year = {2002},
  month = {October},
  volume = {3},
  pages = {2843 -- 2848},
  address = {Lausanne, Switzerland},
  doi = {10.1109/IRDS.2002.1041701},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2002_10_inspection_panoramic.pdf}
}
► H. Baltzakis, A.A. Argyros and P.E. Trahanias, "Fusion of range and visual data for the extraction of scene structure information", In IEEE International Conference on Pattern Recognition (ICPR 2002), IEEE, pp. 7-11, Quebec City, Canada, August 2002. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: In this paper a method for inferring 3D structure information based on both range and visual data is proposed. Data fusion is achieved by validating assumptions formed according to 2D range scans of the environment, through the exploitation of visual information. The proposed method is readily applicable to robot navigation tasks providing significant advantages over existing methods.
BibTeX:
@inproceedings{BaltzakisArgyrosTrahanias2002a,
  author = {Baltzakis, Haris and Argyros, Antonis A and Trahanias, Panos E},
  title = {Fusion of range and visual data for the extraction of scene structure information},
  booktitle = {IEEE International Conference on Pattern Recognition (ICPR 2002)},
  publisher = {IEEE},
  year = {2002},
  month = {August},
  volume = {4},
  pages = {7--11},
  address = {Quebec City, Canada},
  projects =  {WEBFAIR,ACTIPRET},
  doi = {10.1109/ICPR.2002.1047388},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2002_08_icpr_fusion_range_vision.pdf}
}
► A.A. Argyros, K.E. Bekris and S.C. Orphanoudakis, "Robot homing based on corner tracking in a sequence of panoramic images", In IEEE Computer Vision and Pattern Recognition (CVPR 2001), pp. 3-10, Kauai, Hawaii, USA, 2001. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: In robotics, homing can be defined as that behavior which enables a robot to return to its initial (home) position, after traveling a certain distance along an arbitrary path. Odometry has traditionally been used for the implementation of such a behavior, but it has been shown to be an unreliable source of information. In this work, a novel method for visual homing is proposed, based on a panoramic camera. As the robot departs from its initial position, it tracks characteristic features of the environment (corners). As soon as homing is activated, the robot selects intermediate target positions on the original path. These intermediate positions (IPs) are then visited sequentially, until the home position is reached. For the robot to move between two consecutive IPs, it is only required to establish correspondence among at least three corners. This correspondence is obtained through a feature tracking mechanism. The proposed homing scheme is based on the extraction of very low-level sensory information, namely the bearing angles of corners, and has been implemented on a robotic platform. Experimental results show that the proposed scheme achieves homing with a remarkable accuracy, which is not affected by the distance traveled by the robot.
BibTeX:
@inproceedings{ArgyrosBekrisOrphanoudakis2001a,
  author = {Argyros, Antonis A and Bekris, Kostas E and Orphanoudakis, Stelios C},
  title = {Robot homing based on corner tracking in a sequence of panoramic images},
  booktitle = {IEEE Computer Vision and Pattern Recognition (CVPR 2001)},
  year = {2001},
  volume = {2},
  pages = {3--10},
  address = {Kauai, Hawaii, USA},
  url = {http://users.ics.forth.gr/ argyros/res_pan_homing.html},
  doi = {10.1109/CVPR.2001.990917},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2001_12_cvpr_homing_panoramic.pdf}
}
► C. Balas, G. Themelis, A. Papadakis, E. Vasgiouraki, A.A. Argyros, E. Koumantakis, A. Tosca and E. Helidonis, "A novel hyper-spectral imaging system: application on in-vivo detection and grading of cervical precancers and of pigmented skin lesions", In IEEE Computer Vision and Pattern Recognition Workshops (CVPRW 2001), IEEE, Kauai, Hawai, USA, 2001. [Abstract] [BibTeX] [PDF]
Abstract: We present a novel Hyper-Spectral Imaging (HySI) System capable of acquiring and real time displaying of 5nm specrtal images, with 2nm tuning step, in the range of 400nm-1000nm. Synchronized spectral scanning and image storing enables the collection of a stack of calibrated spectral images, from which a fully resolved spectrum per image pixel can be calculated and displayed. We also present results from a pilot use of the developed HySI system as a research tool, in an attempt to develop novel, non-invasive diagnostic methods for the detection and grading of cervical precancers and of pigmented skin lesions. In the case of cervical diagnosis we have succeeded to detect in vivo, quantitatively assess and map alterations in tissue structure and functionality, associated with progress of the disease, with high sensitivity and specificity. In the case of pigmented skin areas, near infrared spectral analysis and imaging of melanin-rich spots show that they become transparent at certain imaging wavelengths and that the transparency wavelength increases with the melanin content and the lesion’s depth. This information can be used for the in vivo quantitative assessment of the later, which is considered to be of great diagnostic and predictive value.
BibTeX:
@inproceedings{BalasThemelisPapadakisEtAl2001a,
  author = {Balas, Costas and Themelis, George and Papadakis, A and Vasgiouraki, E and Argyros, Antonis A and Koumantakis, E and Tosca, A and Helidonis, E},
  title = {A novel hyper-spectral imaging system: application on in-vivo detection and grading of cervical precancers and of pigmented skin lesions},
  booktitle = {IEEE Computer Vision and Pattern Recognition Workshops (CVPRW 2001)},
  publisher = {IEEE},
  year = {2001},
  address = {Kauai, Hawai, USA},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2001_12_cvbvs_hyperspectral.pdf}
}
► M. Roussou, P.E. Trahanias, G. Giannoulis, G. Kamarinos, A.A. Argyros, D.P. Tsakiris, P. Georgiadis, W. Burgard, D. Haehnel, A. Cremers and others, "Experiences from the Use of a Robotic Avatar in a Museum Setting", In Proceedings of the 2001 conference on Virtual reality, archaeology, and cultural heritage, ACM, pp. 153-160, New York, USA, December 2001. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: Access to cultural exhibits is a central issue in museums and exhibition galleries that is recently approached under a new, technological perspective. Although the cultural industries' practices in the cases of museums and cultural exhibits have remained practically unchanged for long, in recent years we are witnessing a gradual adoption of media-technologies in various aspects, such as collections archiving and digital document preservation, media- and Web-presentation, graphical animations, etc. Lately, Internet and Web-based technologies have been employed for providing access, mostly to images of exhibited objects. In few cases, the incorporation of higher-end technology, such as virtual reality, artificial intelligence, or robotics, is explored. In this paper we present such an effort, the TOURBOT project (an acronym for TOUr-guide RoBOT), which emphasizes the development of alternative ways for interactive museum telepresence, essentially through the use of robotic "avatars", and comment on the experience gained from its use in a museum setting.
BibTeX:
@inproceedings{RoussouTrahaniasGiannoulisEtAl2001a,
  author = {Roussou, Maria and Trahanias, Panos E and Giannoulis, George and Kamarinos, George and Argyros, Antonis A and Tsakiris, Dimitris P and Georgiadis, Pantelis and Burgard, Wolfram and Haehnel, Dirk and Cremers, Armin and others},
  title = {Experiences from the Use of a Robotic Avatar in a Museum Setting},
  booktitle = {Proceedings of the 2001 conference on Virtual reality, archaeology, and cultural heritage},
  publisher = {ACM},
  year = {2001},
  month = {December},
  pages = {153--160},
  address = {New York, USA},
  url = {http://users.ics.forth.gr/ argyros/res_robotsinexhibitions.html},
  projects =  {TOURBOT},
  doi = {10.1145/584993.585017},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2001_12_vast_tourbot.pdf},
  videolink = {http://users.ics.forth.gr/ argyros/imgvideo/TourbotInBrief.mpg}
}
► A.A. Argyros, P. Georgiadis, P.E. Trahanias and D.P. Tsakiris, "Semi-Autonomous Navigation of a Robotic Wheelchair", In KTISIVIOS Panhellenic Conference in Robotics and Automation, Santorini, Greece, July 2001. [BibTeX] [URL]
BibTeX:
@inproceedings{ArgyrosGeorgiadisTrahaniasEtAl2001a,
  author = {Argyros, Antonis A and Georgiadis, Pantelis and Trahanias, Panos E and Tsakiris, Dimitris P},
  title = {Semi-Autonomous Navigation of a Robotic Wheelchair},
  booktitle = {KTISIVIOS Panhellenic Conference in Robotics and Automation},
  year = {2001},
  month = {July},
  address = {Santorini, Greece},
  url = {http://users.ics.forth.gr/ argyros/res_pan_track.html}
}
► K. Bekris, K. Hatzopoulos, G. Kazazakis, G. Kontolemakis, M. Masvoula, N. Tsivourakis, A.A. Argyros and P.E. Trahanias, "PYTHEAS: an integrated robotic system with autonomous navigation capabilities", In KTISIVIOS Panhellenic Conference in Robotics and Automation, Santorini, Greece, July 2001. [BibTeX]
BibTeX:
@inproceedings{BekrisHatzopoulosKazazakisEtAl2001a,
  author = {Bekris, Kostas and Hatzopoulos, Kostas and Kazazakis, Giorgos and Kontolemakis, Giorgos and Masvoula, M and Tsivourakis, Nikos and Argyros, Antonis A and Trahanias, Panos E},
  title = {PYTHEAS: an integrated robotic system with autonomous navigation capabilities},
  booktitle = {KTISIVIOS Panhellenic Conference in Robotics and Automation},
  year = {2001},
  month = {July},
  address = {Santorini, Greece}
}
► G. Giannoulis, M. Coliou, G.S. Kamarinos, M. Roussou, P.E. Trahanias, A.A. Argyros, D.P. Tsakiris, A. Cremers, D. Schulz, W. Burgard and others, "Enhancing museum visitor access through robotic avatars connected to the web", In Museums and the Web, pp. 14-17, Seattle, USA, March 2001. [Abstract] [BibTeX] [PDF] [URL] [VIDEO]
Abstract: Access to cultural exhibits is a central issue in museums and exhibition galleries that is recently approached under a new, technological perspective. Although the cultural industries' practices in the cases of museums and cultural exhibits have remained practically unchanged for long, in recent years we are witnessing a gradual adoption of media-technologies in various aspects, such as collections archiving and digital document preservation, media- and Web-presentation, graphical animations, etc. The advent of such technologies contributes towards providing media-rich presentations of cultural exhibits and consequently offering better services to museum visitors. Lately, Internet and Web-based technologies have been employed for providing access, mostly to images of exhibited objects. With current technology, such access is limited due to the non-interactive nature of pre-recorded images or videos and the difficulty in constant updating of the sites when there is change in the content. In few cases, the incorporation of higher-end technology, such as virtual reality, artificial intelligence, or robotics, is explored. Some science museums, large "edutainment" venues, and recreation parks have traditionally been the ones to embrace new media first, by employing fascinating and sophisticated interactive installations and presenting up-to-date results on the creative use of technology. ln this paper we present such an effort, the TOURBOT project, which emphasizes the development of alternative ways for interactive museum telepresence, essentially through the use of robotic "avatars". TOURBOT, an acronym for TOUr-guide RoBOT, represents a collaboration between museums, technology an interactive tour-guide robot able to provide individual access to museums' exhibits and cultural heritage over the Internet. TOURBOT operates as the user's surrogate personna (avatar) in the museum by accepting commands over the web that direct it to move in its physical workspace and visit specific exhibits. In other words, the imaged scene of the museum and the exhibits is communicated over the Internet to the remote visitor As a result the user enjoys a personalized tele-presence to the museum, being able to choose the exhibits to visit, as well as the preferred viewing conditions (point of view, distance to the exhibit, resolution, etc). ln addition to remote interaction with the robot, TOURBOT can also act as a flexible, on-site museum guide to visitors that are physically present. By interacting with the tour-guide robot, museum visitors have the ability to individually exploit the expertise stored in the robot, which can react flexibly to their requirements. It can, for example, offer dedicated tours of specific focus to exhibitions or alternatively give overview tours. As a side effect of this concept, museum visitors get acquainted with new, cutting-edge technology by easily interacting with a complex robotic system. Therefore, technological advances are seamlessly assimilated in everyday activities. This approach to cultural heritage access presents a high degree of novelty as well as a number of technical and conceptual issues and challenges. This paper discusses these issues while analyzing the expected benefits and expectations from visitors, the community, and the museums.
BibTeX:
@inproceedings{GiannoulisColiouKamarinosEtAl2001a,
  author = {Giannoulis, George and Coliou, Mandy and Kamarinos, George S and Roussou, Maria and Trahanias, Panos E and Argyros, Antonis A and Tsakiris, Dimitris P and Cremers, Armin and Schulz, Dirk and Burgard, Wolfram and others},
  title = {Enhancing museum visitor access through robotic avatars connected to the web},
  booktitle = {Museums and the Web},
  year = {2001},
  month = {March},
  pages = {14--17},
  address = {Seattle, USA},
  url = {http://users.ics.forth.gr/ argyros/res_robotsinexhibitions.html},
  projects =  {TOURBOT},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2001_12_mw_tourbot.pdf},
  videolink = {http://users.ics.forth.gr/ argyros/imgvideo/TourbotInBrief.mpg}
}
► A.A. Argyros, C. Bekris and S.C. Orphanoudakis, "Robot homing based on panoramic vision", FORTH-ICS, TR-287, March 2001. [Abstract] [BibTeX] [PDF] [URL]
Abstract: In robotics, homing can be defined as that behavior, which enables a robot to return to its initial (home) position, after traveling a certain distance along an arbitrary path. Odometry has traditionally been used for the implementation of such a behavior, but it has been shown to be an unreliable source of information. In this work, a novel method for visual homing is proposed, based on a panoramic camera. As the robot departs from its initial position, it tracks characteristic features of the environment (corners). As soon as homing is activated, the robot selects intermediate target positions on the original path. These intermediate positions are then visited sequentially, until the home position is reached. For the robot to move between two consecutive intermediate positions, it is only required to establish correspondence among at least three corners. This correspondence is obtained through a feature tracking mechanism. The proposed homing scheme is based on the extraction of very low-level sensory information, namely the bearing angles of corners, and has been implemented on a robotic platform. Experimental results show that the proposed scheme achieves homing with a remarkable accuracy, which is not affected by the distance traveled by the robot.
BibTeX:
@techreport{ArgyrosBekrisOrphanoudakis2001b,
  author = {Argyros, Antonis A and Bekris, Costas and Orphanoudakis, Stelios C},
  title = {Robot homing based on panoramic vision},
  school = {FORTH-ICS},
  year = {2001},
  month = {March},
  number = {TR-287},
  url = {http://users.ics.forth.gr/ argyros/res_pan_homing.html},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2001_03_tr287_forth_robot_homing_panoramic_vision.pdf}
}
► M.I.A. Lourakis, S.V. Tzurbakis, A.A. Argyros and S.C. Orphanoudakis, "Using geometric constraints for matching disparate stereo views of 3D scenes containing planes", In IEEE International Conference on Pattern Recognition (ICPR 2000), IAPR, pp. 419-422, Barcelona, Spain, September 2000. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: Several vision tasks rely upon the availability of sets of corresponding features among images. This paper presents a method which, given some corresponding features in two stereo images, addresses the problem of matching them with features extracted from a second stereo pair captured from a distant viewpoint. The proposed method is based on the assumption that the viewed scene contains two planar surfaces and exploits geometric constraints that are imposed by the existence of these planes to predict the location of image features in the second stereo pair. The resulting scheme handles point and line features in a unified manner and is capable of successfully matching features extracted from stereo pairs acquired from considerably different viewpoints. Experimental results from a prototype implementation demonstrate the effectiveness of the approach.
BibTeX:
@inproceedings{LourakisTzurbakisArgyrosEtAl2000a,
  author = {Lourakis, Manolis I A and Tzurbakis, Stavros V and Argyros, Antonis A and Orphanoudakis, Stelios C},
  title = {Using geometric constraints for matching disparate stereo views of 3D scenes containing planes},
  booktitle = {IEEE International Conference on Pattern Recognition (ICPR 2000)},
  publisher = {IAPR},
  year = {2000},
  month = {September},
  volume = {1},
  pages = {419--422},
  address = {Barcelona, Spain},
  url = {http://users.ics.forth.gr/ argyros/res_matching.html},
  doi = {10.1109/ICPR.2000.905366},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2000_09_icpr_feature_transfer_and_matching.pdf}
}
► D.P. Tsakiris and A.A. Argyros, "Corridor following by mobile robots equipped with panoramic cameras", In IEEE Mediterranean Conference on Control and Automation (MED 2000), IEEE, Patras, Greece, July 2000. [Abstract] [BibTeX] [PDF] [URL] [VIDEO]
Abstract: The present work considers corridor–following maneuvers for non-holonomic mobile robots, guided by sensory data acquired by panoramic cameras. The panoramic vision system provides information from an environment with textured walls to the motion control system, which drives the robot along a corridor. Panoramic cameras have a 360 degrees visual field, a capability that the proposed control methods exploit. In our sensor–based control scheme, optical flow information from several distinct viewing directions in the entire field of view of the panoramic camera is used directly in the control loop, without the need for state reconstruction. The interest of this lies in the fact that the optical flow information is not sufficient to reconstruct the state of the system, it is however sufficient for the proposed control law to accomplish the desired task. Driving the robot along a corridor amounts to the asymptotic stabilization of a subsystem of the robot’s kinematics and the proposed control schemes are shown to achieve this goal.
BibTeX:
@inproceedings{TsakirisArgyros2000b,
  author = {Tsakiris, Dimitris P and Argyros, Antonis A},
  title = {Corridor following by mobile robots equipped with panoramic cameras},
  booktitle = {IEEE Mediterranean Conference on Control and Automation (MED 2000)},
  publisher = {IEEE},
  year = {2000},
  month = {July},
  address = {Patras, Greece},
  url = {http://users.ics.forth.gr/ argyros/res_biomimeticcentering.html},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2000_07_med_corridor_following_panoramic.pdf},
  videolink = {http://users.ics.forth.gr/ argyros/imgvideo/CorridorFollowing.avi}
}
► D.P. Tsakiris and A.A. Argyros, "Nonholonomic mobile robots equipped with panoramic cameras: Corridor following", FORTH-ICS, vol. 26, TR-272, June 2000. [Abstract] [BibTeX] [PDF] [URL] [VIDEO]
Abstract: The present work considers corridor-following maneuvers for mobile robots with nonholonomic constraints, guided by sensory data acquired by panoramic cameras. The panoramic vision system provides information from an environment with textured walls to the motion control system, which drives the robot along a corridor. Panoramic cameras have a 360 degrees visual field, a capability that the proposed control methods attempt to exploit. We consider two types of sensor-based controllers: one is a path-following state feedback control law where the state of the robot inside the corridor is reconstructed from the visual data; in the other, optical flow information from several distinct "looking" directions in the field of view of the panoramic camera is used directly in the control loop, without the need for state reconstruction. The interest of the second type of controllers lies in the fact that this optical flow information is not sufficient to reconstruct the state of the system, it is however sufficient for the proposed control law to accomplish the desired task. Driving the robot along a corridor amounts to the asymptotic stabilization of a subsystem of the robot's kinematics and the proposed control schemes are shown to achieve this goal.
BibTeX:
@techreport{TsakirisArgyros2000a,
  author = {Tsakiris, Dimitris P and Argyros, Antonis A},
  title = {Nonholonomic mobile robots equipped with panoramic cameras: Corridor following},
  school = {FORTH-ICS},
  year = {2000},
  month = {June},
  volume = {26},
  number = {TR-272},
  url = {http://users.ics.forth.gr/ argyros/res_biomimeticcentering.html},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2000_06_tr272_forth_corridor_following_panoramic.pdf},
  videolink = {http://users.ics.forth.gr/ argyros/imgvideo/CorridorFollowing.avi}
}
► P.E. Trahanias, A.A. Argyros, D.P. Tsakiris, A. Cremers, D. Schulz, W. Burgard, D. Haehnel, V. Savvaides, G. Giannoulis, M. Coliou and others, "Tourbot-interactive museum tele-presence through robotic avatars", In International WWW Conference, Culture track, Amsterdam, Netherlands, May 2000. [Abstract] [BibTeX] [PDF] [URL] [VIDEO]
Abstract: TOURBOT, the acronym of a project entitled “Interactive Museum Tele-presence Through Robotic Avatars”, represents an EU-IST funded activity aiming at developing alternative ways for interactive museum tele-presence [1]. In this paper we present the project framework, with emphasis on the project goals, approach and innovations, as well as the expected benefits and results. The overal goal of TOURBOT is the development of an interactive tour-guide robot able to provide individual access to museums’ exhibits and cultural heritage over the Internet. TOURBOT operates as the user’s avatar in the museum (i.e. as a remote “representative” of the user, able to carry out actions and transmit information), by accepting commands over the Web that direct it to move in its workspace and visit specific exhibits; besides, TOURBOT can also act as a flexible, on-site museum guide. More specifically, the TOURBOT objectives are: (1) to develop a robotic avatar with advanced navigation capabilities that will be able to move autonomously in the museum’s premises, (2) to implement appropriate Web interfaces to the robotic avatar that will realize distant-user’s telepresence, i.e. facilitate scene observation through the avatars eyes, (3) to facilitate personalized and realistic observation of the museum exhibits, and (4) to enable on-site, interactive museum tour-guides.
BibTeX:
@inproceedings{TrahaniasArgyrosTsakirisEtAl2000a,
  author = {Trahanias, Panos E and Argyros, Antonis A and Tsakiris, Dimitris P and Cremers, Armin and Schulz, Dirk and Burgard, Wolfram and Haehnel, Dirk and Savvaides, Vassilis and Giannoulis, George and Coliou, Mandy and others},
  title = {Tourbot-interactive museum tele-presence through robotic avatars},
  booktitle = {International WWW Conference, Culture track},
  year = {2000},
  month = {May},
  volume = {7},
  address = {Amsterdam, Netherlands},
  url = {http://users.ics.forth.gr/ argyros/res_robotsinexhibitions.html},
  projects =  {TOURBOT},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2000_05_www9_tourbot.pdf},
  videolink = {http://users.ics.forth.gr/ argyros/imgvideo/TourbotInBrief.mpg}
}
► M.I.A. Lourakis, S.V. Tzurbakis, A.A. Argyros and S.C. Orphanoudakis, "Using Geometric Constraints for Matching Disparate Stereo Views of 3D Scenes Containing Planes", FORTH-ICS, TR-268, February 2000. [Abstract] [BibTeX] [PDF] [URL]
Abstract: Several vision tasks rely upon the availability of sets of corresponding features among images. This paper presents a method which, given some corresponding features in two stereo images, addresses the problem of matching them with features extracted from a second stereo pair captured from a distant viewpoint. The proposed method is based on the assumption that the viewed scene contains two planar surfaces and exploits geometric constraints that are imposed by the existence of these planes to predict the location of image features in the second stereo pair. The resulting scheme handles point and line features in a unified manner and is capable of successfully matching features extracted from stereo pairs acquired from considerably different viewpoints. Experimental results from a prototype implementation demonstrate the effectiveness of the approach.
BibTeX:
@techreport{LourakisTzurbakisArgyrosEtAl2000b,
  author = {Lourakis, Manonis I A and Tzurbakis, Stavros V and Argyros, Antonis A and Orphanoudakis, Stelios C},
  title = {Using Geometric Constraints for Matching Disparate Stereo Views of 3D Scenes Containing Planes},
  school = {FORTH-ICS},
  year = {2000},
  month = {February},
  number = {TR-268},
  url = {http://users.ics.forth.gr/ argyros/res_matching.html},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/2000_02_tr268_forth_feature_matching_transfer.pdf}
}
► A.A. Argyros and F. Bergholm, "Combining central and peripheral vision for reactive robot navigation", In IEEE Computer Vision and Pattern Recognition (CVPR 1999), IEEE, pp. 646-651, Fort Collins, Colorado, USA, 1999. [Abstract] [BibTeX] [DOI] [PDF] [URL] [VIDEO]
Abstract: In this paper we present a new method for vision-based, reactive robot navigation that enables a robot to move in the middle of the free space by exploiting both central and peripheral vision. The robot employs a forward-looking camera for central vision and two side-looking cameras for sensing the periphery of its visual field. The developed method combines the information acquired by this trinocular vision system and produces low-level motor commands that keep the robot in the middle of the free space. The approach follows the purposive vision paradigm in the sense that vision is not studied in isolation but in the context of the behaviors that the system is engaged as well as the environment and the robot's motor capabilities. It is demonstrated that by taking into account these issues, vision processing can be drastically simplified still giving rise to quite complex behaviors. The proposed method does not make strict assumptions about the environment, requires very low level information to be extracted from the images, produces a robust robot behavior and is computationally efficient. Results obtained by bath simulations and from a prototype on-line implementation demonstrate the effectiveness of the method
BibTeX:
@inproceedings{ArgyrosBergholm1999a,
  author = {Argyros, Antonis A and Bergholm, Fredrik},
  title = {Combining central and peripheral vision for reactive robot navigation},
  booktitle = {IEEE Computer Vision and Pattern Recognition (CVPR 1999)},
  publisher = {IEEE},
  year = {1999},
  volume = {2},
  pages = {646--651},
  address = {Fort Collins, Colorado, USA},
  url = {http://users.ics.forth.gr/ argyros/res_bees.html},
  doi = {10.1109/CVPR.1999.784994},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/1999_06_cvpr_flow_balancing_trinocular.pdf},
  videolink = {http://users.ics.forth.gr/ argyros/imgvideo/Centering3cameras.mpg}
}
► A.A. Argyros, P.E. Trahanias and S.C. Orphanoudakis, "Robust regression for the detection of independent 3D motion by a binocular observer", Real-Time Imaging, Academic Press, vol. 4, no. 2, pp. 125-141, 1998. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: A method is proposed for the visual detection of objects that move independently of the observer in a 3D dynamic environment. Many of the existing techniques for solving this problem are based on 2D motion models, which is equivalent to assuming that all the objects in a scene are at a constant depth from the observer. Although such methods perform well if this assumption holds, they may give erroneous results when applied to scenes with large depth variations. Additionally, many of the existing techniques rely on the computation of optical flow, which amounts to solving the ill-posed correspondence problem. In this paper, independent 3D motion detection is formulated using 3D models and is approached as a problem of robust regression applied to visual input acquired by a binocular, rigidly moving observer. Similar analysis is applied both to the stereoscopic data taken by a non-calibrated stereoscopic system and to the motion data obtained from successive frames m time. Least Median of Squares (LMedS) estimation is applied to stereoscopic data to produce maps of image regions characterized by a dominant depth. LMedS is also applied to the motion data that are related to the points at the dominant depth, to segment the latter with respect to 3D motion. In contrast to the methods that rely on 2D models, the proposed method performs accurately, even in the case of scenes with large depth variations. Both stereo and motion processing is based on the normal flow field, which (in contrast to the optical flow field) can be robustly computed from the spatiotemporal derivatives of the image intensity function. Although parts of the proposed scheme have non-trivial computational requirements, computations can be expedited by various ways which are discussed in detail. This is also demonstrated by an on-board implementation of the method on a mobile robotic platform. The method has been evaluated using synthetic as well as real data. Sample results show the effectiveness and robustness of the proposed scheme.
BibTeX:
@article{ArgyrosTrahaniasOrphanoudakis1998a,
  author = {Argyros, Antonis A and Trahanias, Panos E and Orphanoudakis, Stelios C},
  title = {Robust regression for the detection of independent 3D motion by a binocular observer},
  journal = {Real-Time Imaging},
  publisher = {Academic Press},
  year = {1998},
  volume = {4},
  number = {2},
  pages = {125--141},
  url = {http://users.ics.forth.gr/ argyros/res_imd.html},
  doi = {10.1006/rtim.1997.0055},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/1998_04_journal_rti_imd.pdf}
}
► A.A. Argyros and F. Bergholm, "Reactive Robot Navigation Based on a Combination of Central and Peripheral Vision", In Computer Vision and Mobile Robotics Workshop (CVMR 1998), Santorini, Greece, 1998. [Abstract] [BibTeX] [PDF] [URL] [VIDEO]
Abstract: In this paper, we present a new method for vision-based, reactive robot navigation that enables a robot to move in the middle of the free space by exploiting both central and peripheral vision. The system employs a forward-looking camera for central vision and two side-looking cameras for sensing the periphery of the robot’s visual field. The developed method combines the information acquired by this trinocular vision system and produces low-level motor commands that keep the robot in the middle of the free space. The approach follows the purposive vision paradigm in the sense that vision is not studied in isolation but in the context of the behaviors that the system is engaged as well as the environment and the motor capabilities of the robot. It is demonstrated that by taking into account these issues, vision processing can be drastically simplified, still giving rise to quite rich behaviors. The advantages of the method is that it does not make strict assumptions about the environment, it requires very low level information to be extracted from the images, it produces a robust robot behavior and it is computationally very efficient. Results obtained by both simulations and from a prototype on-line implementation demonstrate the effectiveness of the method.
BibTeX:
@inproceedings{ArgyrosBergholm1998a,
  author = {Argyros, Antonis A and Bergholm, Fredrik},
  title = {Reactive Robot Navigation Based on a Combination of Central and Peripheral Vision},
  booktitle = {Computer Vision and Mobile Robotics Workshop (CVMR 1998)},
  year = {1998},
  address = {Santorini, Greece},
  url = {http://users.ics.forth.gr/ argyros/res_bees.html},
  projects =  {VIRGO},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/1998_09_cvmr_flow_balancing_trinocular.pdf},
  videolink = {http://users.ics.forth.gr/ argyros/imgvideo/Centering3cameras.mpg}
}
► A.A. Argyros, "Reactive Robot Navigation: A Purposive Approach", In Proceedings of the EU TMR Networks Conference, Graz, Austria, May 1998. [BibTeX] [PDF] [URL] [VIDEO]
BibTeX:
@inproceedings{Argyros1998a,
  author = {Argyros, Antonis A},
  title = {Reactive Robot Navigation: A Purposive Approach},
  booktitle = {Proceedings of the EU TMR Networks Conference},
  year = {1998},
  month = {May},
  address = {Graz, Austria},
  url = {http://users.ics.forth.gr/ argyros/res_bees.html},
  projects =  {VIRGO},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/1998_05_eu-tmrconf_flow_balancing_trinocular.pdf},
  videolink = {http://users.ics.forth.gr/ argyros/imgvideo/Centering3cameras.mpg}
}
► M.I.A. Lourakis, A.A. Argyros and S.C. Orphanoudakis, "Independent 3D motion detection using residual parallax normal flow fields", In IEEE International Conference on Computer Vision (ICCV 1998), IEEE, pp. 1012-1017, Santa Barbara, CA, USA, January 1998. [Abstract] [BibTeX] [DOI] [URL]
Abstract: This paper considers a specific problem of visual perception of motion, tamely the problem of visual detection of independent 3D motion. Most of the existing techniques for solving this problem rely on restrictive assumptions about the environment, the observer's motion, or both. Moreover, they are based on the computation of a dense optical flow field, which amounts to solving the ill-posed correspondence problem. In this work independent motion detection is formulated as a problem of robust parameter estimation applied to the visual input acquired by a rigidly moving observer. The proposed method automatically selects a planar surface in the scene and the residual planar parallax normal flow field with respect to the motion of this surface is computed at two successive time! instants. The two resulting normal flow fields are then combined in a linear model. The parameters of this model are related to the parameters of self-motion (ego-motion) and their robust estimation leads to a segmentation of the scene based on 3D motion. The method avoids a complete solution to the correspondence problem by selectively matching subsets of image points and by employing normal flow fields. Experimental results demonstrate the effectiveness of the proposed method in detecting independent motion in scenes with large depth variations and unrestricted observer motion
BibTeX:
@inproceedings{LourakisArgyrosOrphanoudakis1998a,
  author = {Lourakis, Manolis I A and Argyros, Antonis A and Orphanoudakis, Stelios C},
  title = {Independent 3D motion detection using residual parallax normal flow fields},
  booktitle = {IEEE International Conference on Computer Vision (ICCV 1998)},
  publisher = {IEEE},
  year = {1998},
  month = {January},
  pages = {1012--1017},
  address = {Santa Barbara, CA, USA},
  url = {http://users.ics.forth.gr/ argyros/res_imd.html},
  doi = {10.1109/ICCV.1998.710840}
}
► A.A. Argyros and S.C. Orphanoudakis, "Detecting Independently Moving Objects by Eliminating Depth in Normal Flow Fields", FORTH-ICS, TR-189, 1997. [Abstract] [BibTeX] [PDF] [URL]
Abstract: This paper considers a specific problem of visual perception of motion, namely the problem of visual detection of independent 3D motion. Most of the existing techniques for solving this problem rely on restrictive assumptions about the environment, the observer’s motion, or both. Moreover, they are based on the computation of optical flow, which amounts to solving the ill-posed correspondence problem. In this work, independent motion detection is formulated as robust parameter estimation applied to the visual input acquired by a binocular, rigidly moving observer. Depth and motion measurements are combined in a linear model. The parameters of this model are related to the parameters of self-motion (egomotion) and the parameters of the stereoscopic configuration of the observer. The robust estimation of this model leads to a segmentation of the scene based on 3D motion. The method avoids the correspondence problem by employing only normal flow fields. Experimental results demonstrate the effectiveness of this method in detecting independent motion in scenes with large depth variations, without any constraints imposed on observer motion.
BibTeX:
@techreport{ArgyrosOrphanoudakis1997b,
  author = {Argyros, Antonis A and Orphanoudakis, Stelios C},
  title = {Detecting Independently Moving Objects by Eliminating Depth in Normal Flow Fields},
  school = {FORTH-ICS},
  year = {1997},
  number = {TR-189},
  url = {http://users.ics.forth.gr/ argyros/res_imd.html},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/1997_03_tr189_forth_imd_depth_elimination_normal_flows.pdf}
}
► M.I.A. Lourakis, A.A. Argyros and S.C. Orphanoudakis, "Independent 3D Motion Detection Using Residual Parallax Normal Flow Fields", FORTH-ICS, TR-206, 1997. [BibTeX] [URL]
BibTeX:
@techreport{LourakisArgyrosOrphanoudakis1997a,
  author = {Lourakis, Manolis I A and Argyros, Antonis A and Orphanoudakis, Stelios C},
  title = {Independent 3D Motion Detection Using Residual Parallax Normal Flow Fields},
  school = {FORTH-ICS},
  year = {1997},
  number = {TR-206},
  url = {http://users.ics.forth.gr/ argyros/res_imd.html}
}
► P.E. Trahanias, S.C. Orphanoudakis, J. Arnspang, F. Bergholm, K. Chandrinos, K. Henriksen, J. Hertzberg, L. Gaga, C.B. Madsen and J. Santos-Victor, "Analysis of Current Approaches in Automated Vision-based Navigation", FORTH-ICS, 1997. [BibTeX] [PDF] [URL]
BibTeX:
@techreport{TrahaniasOrphanoudakisArnspangEtAl1997a,
  author = {Trahanias, Panos E and Orphanoudakis, Stelios C and Arnspang, Jens and Bergholm, Fredrik and Chandrinos, Kostas and Henriksen, Knud and Hertzberg, Joachim and Gaga, Lena and Madsen, Claus B and Santos-Victor, Jose},
  title = {Analysis of Current Approaches in Automated Vision-based Navigation},
  school = {FORTH-ICS},
  year = {1997},
  url = {http://users.ics.forth.gr/ argyros},
  projects =  {VIRGO},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/1997_07_virgo_report_vision_based_navigation.pdf}
}
► A.A. Argyros and S.C. Orphanoudakis, "Independent 3d motion detection based on depth elimination in normal flow fields", In IEEE Computer Vision and Pattern Recognition (CVPR 1997), IEEE, pp. 672-677, San Juan, Puerto Rico, USA, June 1997. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: This paper considers a specific problem of visual perception of motion, namely the problem of visual detection of independent 3D motion. Most of the existing techniques for solving this problem rely on restrictive assumptions about the environment, the observer's motion, or both. Moreover they are based on the computation of optical flow, which amounts to solving the ill-posed correspondence problem. In this work, independent motion detection is formulated as robust parameter estimation applied to the visual input acquired by a binocular rigidly moving observer. Depth and motion measurements are combined in a linear model. The parameters of this model are related to the parameters of self-motion (egomotion) and the parameters of the stereoscopic configuration of the observer. The robust estimation of this model leads to a segmentation of the scene based on 3D motion. The method avoids the correspondence problem by employing only normal flow fields. Experimental results demonstrate the effectiveness of this method in detecting independent motion in scenes with large depth variations, without any constraints imposed on observer motion.
BibTeX:
@inproceedings{ArgyrosOrphanoudakis1997a,
  author = {Argyros, Antonis A and Orphanoudakis, Stelios C},
  title = {Independent 3d motion detection based on depth elimination in normal flow fields},
  booktitle = {IEEE Computer Vision and Pattern Recognition (CVPR 1997)},
  publisher = {IEEE},
  year = {1997},
  month = {June},
  pages = {672--677},
  address = {San Juan, Puerto Rico, USA},
  url = {http://users.ics.forth.gr/ argyros/res_imd.html},
  doi = {10.1109/CVPR.1997.609398},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/1997_06_cvpr_imd_depth_elimination_normal_flow.pdf}
}
► P.E. Trahanias, M.I.A. Lourakis, A.A. Argyros and S.C. Orphanoudakis, "Navigational support for robotic wheelchair platforms: an approach that combines vision and range sensors", In IEEE International Conference on Robotics and Automation (ICRA 1997), IEEE, pp. 1265-1270, Albuquerque, New Mexico, USA, April 1997. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: An approach towards providing advanced navigational support to robotic wheelchair platforms is presented. In order to avoid any modifications to the environment, we propose an approach that employs computer vision techniques which facilitate space perception and navigation. Computer vision has not been introduced to date in rehabilitation robotics, since the former is not mature enough to meet the needs of this sensitive application. However, in the proposed approach, stable techniques are exploited that facilitate reliable, automatic navigation to any point in the visible environment. Preliminary results obtained from its implementation on a laboratory robotic platform indicate its usefulness and flexibility.
BibTeX:
@inproceedings{TrahaniasLourakisArgyrosEtAl1997a,
  author = {Trahanias, Panos E and Lourakis, Manonlis I A and Argyros, Antonis A and Orphanoudakis, Stelios C},
  title = {Navigational support for robotic wheelchair platforms: an approach that combines vision and range sensors},
  booktitle = {IEEE International Conference on Robotics and Automation (ICRA 1997)},
  publisher = {IEEE},
  year = {1997},
  month = {April},
  volume = {2},
  pages = {1265--1270},
  address = {Albuquerque, New Mexico, USA},
  doi = {10.1109/ROBOT.1997.614311},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/1997_04_icra_wheelchair_navigation.pdf}
}
► A.A. Argyros, M.I.A. Lourakis, P.E. Trahanias and S.C. Orphanoudakis, "Real-time Detection of Maneuvering Objects by a Monocular Observer", FORTH-ICS, TR-160, 1996. [Abstract] [BibTeX] [PDF] [URL]
Abstract: A method is proposed for real-time detection of objects that maneuver in the visual field of a monocular observer. Such cases are common in natural environments where the 3D motion parameters of certain objects (e.g. animals) change considerably over time. The approach taken conforms with the theory of purposive vision, according to which vision algorithms should solve many, specific problems under loose assumptions. The method can effectively answer two important questions: (a) whether the observer has changed his 3D motion parameters, and (b) in case that the observer has constant 3D motion, whether there are any maneuvering objects (objects with non-constant 3D motion parameters) in his visual field. The approach is direct in the sense that the structure from motion problem - which can only be solved under restrictive assumptions - is avoided. Essentially, the method relies on a pointwise comparison of two normal flow fields which can be robustly computed from three successive frames. Thus, it by-passes the ill-posed problem of optical flow computation. Experimental results demonstrate the effectiveness and robustness of the proposed scheme. Moreover, the computational requirements of the method are extremely low, making it a likely candidate for real-time implementation.
BibTeX:
@techreport{ArgyrosLourakisTrahaniasEtAl1996f,
  author = {Argyros, Antonis A and Lourakis, Manolis I A and Trahanias, Panos E and Orphanoudakis, Stelios C},
  title = {Real-time Detection of Maneuvering Objects by a Monocular Observer},
  school = {FORTH-ICS},
  year = {1996},
  number = {TR-160},
  url = {http://users.ics.forth.gr/ argyros},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/1996_02_tr160_forth_imd_maneuvering_object_detection.pdf}
}
► A.A. Argyros, M.I.A. Lourakis, P.E. Trahanias and S.C. Orphanoudakis, "Fast Visual Detection of Changes in 3D Motion", In Machine Vision Applications (MVA 1996), pp. 216-219, Tokyo, Japan, November 1996. [Abstract] [BibTeX] [PDF]
Abstract: A method is proposed for the fast detection of objects that maneuver in the visual field of a monocular observer. Such cases are common in natural environments where the 3D motion parameters of certain objects (e.g. animals) change considerably over time. The approach taken conforms with the theory of purposive vision, according to which vision algorithms should solve many, specific problems under loose assumptions. The method can effectively answer two important questions: (a) whether the observer has changed his 3D motion parameters, and (b) in case that the observer has constant 3D motion, whether there are any maneuvering objects (objects with non-constant 3D motion parameters) in his visual field. Essentially, the method relies on a pointwise comparison of two normal flow fields which can be robustly computed from three successive frames. Thus, it by-passes the ill-posed problem of optical flow computation. Experimental results demonstrate the effectiveness and robustness of the proposed scheme. Moreover, the computational requirements of the method are extremely low, making it a likely candidate for real-time implementation.
BibTeX:
@inproceedings{ArgyrosLourakisTrahaniasEtAl1996b,
  author = {Argyros, Antonis A and Lourakis, Manolis I A and Trahanias, Panos E and Orphanoudakis, Stelios C},
  title = {Fast Visual Detection of Changes in 3D Motion},
  booktitle = {Machine Vision Applications (MVA 1996)},
  year = {1996},
  month = {November},
  pages = {216--219},
  address = {Tokyo, Japan},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/1996_11_mva_imd_changes.pdf}
}
► A.A. Argyros, M.I.A. Lourakis, P.E. Trahanias and S.C. Orphanoudakis, "Qualitative detection of 3D motion discontinuities", In IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 1996), IEEE, pp. 1630-1637, Osaka, Japan, November 1996. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: This paper presents a method for the detection of objects that move independently of the observer in a 3D dynamic scene, Independent motion detection is achieved through processing of stereoscopic image sequences acquired by a binocular, rigidly moving observer. A weak assumption is made about the observer's motion (egomotion), namely that the direction of the translational and rotational components of egomotion are constant in small image patches. This assumption facilitates the extraction of qualitative information about depth from motion, while additional qualitative depth information is independently computed from image stereo pairs acquired by the binocular vision system. Robust regression in the form of least median of squares estimation is applied within each image patch to test for consistency between the depth functions computed from motion and stereo. Possible inconsistencies signal the presence of independently moving objects. In contrast to other existing approaches for independent motion detection, which are based on the ill-posed problem of optical flow computation, the proposed method relies on normal flow fields for both stereo and motion processing. By exploiting local constraints of qualitative nature, the problem of independent motion detection is approached directly, without relying on a solution to the general structure from motion problem. Experimental results indicate that the proposed method is both effective and robust.
BibTeX:
@inproceedings{ArgyrosLourakisTrahaniasEtAl1996c,
  author = {Argyros, Antonis A and Lourakis, Manolis I A and Trahanias, Panos E and Orphanoudakis, Stelios C},
  title = {Qualitative detection of 3D motion discontinuities},
  booktitle = {IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 1996)},
  publisher = {IEEE},
  year = {1996},
  month = {November},
  volume = {3},
  pages = {1630--1637},
  address = {Osaka, Japan},
  url = {http://users.ics.forth.gr/ argyros/res_imd.html},
  doi = {10.1109/IROS.1996.569030},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/1996_11_iros_imd_motion_discontinuities.pdf}
}
► G. Sandini, A.A. Argyros, E. Auffret, P. Dario, B. Dierickx, F. Ferrari, H. Frowein, C. Guerin, L. Hermans, A. Manganas and others, "Image-based personal communication using an innovative space-variant CMOS sensor", In IEEE International Workshop on Robot and Human Communication, 1996, IEEE, pp. 158-163, Tsukuba, Japan, November 1996. [Abstract] [BibTeX] [DOI] [PDF]
Abstract: This paper reports the result of IBIDEM, a collaborative project supported by the European Union under the Technology Initiative for Elderly and Disabled People-TIDE initiative. The goal of the project has been to build a prototype of a videophone, connected to standard PSTN lines, that can be used by hearing impaired persons in face-to-face communication. The most innovative content of the project has been the design, fabrication and use of a new generation of space-variant visual sensor characterized by a spatial resolution decreasing linearly with distance from the geometric center of the sensor's chip. This sampling strategy allows, with a limited number of pixels and consequently a high frame rate, transmission of high resolution information for “speech-reading” and a wide field of view for facial expressions and gestures.
BibTeX:
@inproceedings{SandiniArgyrosAuffretEtAl1996a,
  author = {Sandini, Giulio and Argyros, Antonis A and Auffret, E and Dario, Paolo and Dierickx, B and Ferrari, F and Frowein, H and Guerin, C and Hermans, L and Manganas, Andreas and others},
  title = {Image-based personal communication using an innovative space-variant CMOS sensor},
  booktitle = {IEEE International Workshop on Robot and Human Communication, 1996},
  publisher = {IEEE},
  year = {1996},
  month = {November},
  pages = {158--163},
  address = {Tsukuba, Japan},
  projects =  {IBIDEM},
  doi = {10.1109/ROMAN.1996.568790},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/1992_07_tr048_forth_load_redistribution_in_vision.pdf}
}
► A.A. Argyros, M.I.A. Lourakis, P.E. Trahanias and S.C. Orphanoudakis, "Qualitative Detection of 3D Motion Discontinuities", FORTH-ICS, TR-177, October 1996. [BibTeX] [URL]
BibTeX:
@techreport{ArgyrosLourakisTrahaniasEtAl1996e,
  author = {Argyros, Antonis A and Lourakis, Manolis I A and Trahanias, Panos E and Orphanoudakis, Stelios C},
  title = {Qualitative Detection of 3D Motion Discontinuities},
  school = {FORTH-ICS},
  year = {1996},
  month = {October},
  number = {TR-177},
  url = {http://users.ics.forth.gr/ argyros}
}
► P.E. Trahanias, M.I.A. Lourakis, A.A. Argyros and S.C. Orphanoudakis, "Vision-Based Assistive Navigation for Robotic Wheelchair Platforms", FORTH-ICS, TR-178, October 1996. [Abstract] [BibTeX] [PDF] [URL]
Abstract: In this paper we present an approach towards providing advanced navigational capabilities to robotic wheelchair platforms. Contemporary methods that are employed in robotic wheelchairs are based on the information provided by range sensors and its appropriate exploitation by means of obstacle avoidance techniques. However, since range sensors cannot support a detailed environment representation, these methods fail to provide advanced navigational assistance, unless the environment is appropriately regulated (e.g. with the introduction of beacons). In order to avoid any modifications to the environment, we propose an alternative approach that employs computer vision techniques which facilitate space perception and navigation. Computer vision has not been introduced todate in rehabilitation robotics, since the former is not mature and reliable enough to meet the needs of this sensitive application. However, in the proposed approach, stable techniques are exploited that facilitate reliable, automatic navigation to any point in the visible environment. This greatly enhances the mobility of the elderly and disabled, without requiring them to exercise fine motor control. Preliminary results obtained from the implementation of this approach on a laboratory robotic platform indicate its usefulness and flexibility.
BibTeX:
@techreport{TrahaniasLourakisArgyrosEtAl1996b,
  author = {Trahanias, Panos E and Lourakis, Manolis I A and Argyros, Antonis A and Orphanoudakis, Stelios C},
  title = {Vision-Based Assistive Navigation for Robotic Wheelchair Platforms},
  school = {FORTH-ICS},
  year = {1996},
  month = {October},
  number = {TR-178},
  url = {http://users.ics.forth.gr/ argyros},
  projects =  {VIRGO},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/1996_10_tr178_forth_robotic_wheechair.pdf}
}
► A.A. Argyros, "Visual Detection of Independent 3D Motion by a Moving Observer", Ph.D. Thesis, Computer Science Department, University of Crete, October 1996. [BibTeX] [URL]
BibTeX:
@phdthesis{Argyros1996a,
  author = {Argyros, Antonis A},
  title = {Visual Detection of Independent 3D Motion by a Moving Observer},
  school = {Computer Science Department, University of Crete},
  year = {1996},
  month = {October},
  url = {http://users.ics.forth.gr/ argyros/res_imd.html}
}
► A.A. Argyros, M.I.A. Lourakis, P.E. Trahanias and S.C. Orphanoudakis, "Independent 3D Motion Detection through Robust Regression in Depth Layers", In British Machine Vision Conference (BMVC 1996), BMVA, pp. 535-544, Edinburgh, UK, September 1996. [Abstract] [BibTeX] [DOI] [PDF] [URL]
Abstract: This paper presents a novel method for the detection of objects that move independently of the observer in a 3D dynamic environment. Independent 3D motion detection is formulated as a problem of robust regression applied to visual input acquired by a binocular, rigidly moving observer. The qualitative analysis of images acquired by a parallel stereo configuration yields a segmentation of a scene into depth layers. A depth layer consists of points of the 3D space for which depth variations are small compared to the distance from the observer. Robust regression is applied to each depth layer in order to segment the latter into coherently moving regions. Finally, a combination stage is applied across all layers in order to come up with an integrated view of independent motion in the whole 3D scene. In contrast to other existing approaches for independent motion detection which are based on the ill-posed problem of optical flow computation, the proposed method relies on normal flow fields for both stereo and motion processing. Experimental results show the effectiveness and robustness of the proposed scheme, which is capable of discriminating independent 3D motion in scenes with large depth variations.
BibTeX:
@inproceedings{ArgyrosLourakisTrahaniasEtAl1996a,
  author = {Argyros, Antonis A and Lourakis, Manolis I A and Trahanias, Panos E and Orphanoudakis, Stelios C},
  title = {Independent 3D Motion Detection through Robust Regression in Depth Layers},
  booktitle = {British Machine Vision Conference (BMVC 1996)},
  publisher = {BMVA},
  year = {1996},
  month = {September},
  pages = {535--544},
  address = {Edinburgh, UK},
  url = {http://users.ics.forth.gr/ argyros/res_imd.html},
  doi = {10.5244/C.10.1},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/1996_09_bmvc_imd_in_depth_layers.pdf}
}
► P.E. Trahanias, M.I.A. Lourakis, A.A. Argyros and S.C. Orphanoudakis, "Vision-Based Assistive Navigation for Robotic Wheelchair Platforms", In Machine Perception Applications, pp. 43-57, Graz, Austria, September 1996. [Abstract] [BibTeX] [PDF]
Abstract: Abstract: In this paper we present an approach towards providing advanced navigational capabilities to robotic wheelchair platforms. Contemporary methods that are employed in robotic wheelchairs are based on the information provided by range sensors and its appropriate exploitation by means of obstacle avoidance techniques. However, since range sensors cannot support a detailed environment representation, these methods fail to provide advanced navigational assistance, unless the environment is appropriately regulated (e.g. with the introduction of beacons). In order to avoid any modifications to the environment, we propose an alternative approach that employs computer vision techniques which facilitate space perception and navigation. Computer vision has not been introduced todate in rehabilitation robotics, since the former is not mature and reliable enough to meet the needs of this sensitive application. However, in the proposed approach, stable techniques are exploited that facilitate reliable, automatic navigation to any point in the visible environment. This greatly enhances the mobility of the elderly and disabled, without requiring them to exercise fine motor control. Preliminary results obtained from the implementation of this approach on a laboratory robotic platform indicate its usefulness and flexibility.
BibTeX:
@inproceedings{TrahaniasLourakisArgyrosEtAl1996a,
  author = {Trahanias, Panos E and Lourakis, Manolis I A and Argyros, Antonis A and Orphanoudakis, Stelios C},
  title = {Vision-Based Assistive Navigation for Robotic Wheelchair Platforms},
  booktitle = {Machine Perception Applications},
  year = {1996},
  month = {September},
  pages = {43--57},
  address = {Graz, Austria},
  projects =  {VIRGO},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/1996_09_IAPR_TC-8_assistive_navigation.pdf}
}
► A.A. Argyros, M.I.A. Lourakis, P.E. Trahanias and S.C. Orphanoudakis, "Independent 3D Motion Detection Through Robust Regression in Depth Layers", FORTH-ICS, TR-159, February 1996. [Abstract] [BibTeX] [URL]
Abstract: This paper presents a novel method for the detection of objects that move independently of the observer in a 3D dynamic environment. Independent 3D motion detection is formulated as a problem of robust regression applied to visual input acquired by a binocular, rigidly moving observer. The qualitative analysis of images acquired by a parallel stereo configuration yields a segmentation of a scene into depth layers. A depth layer consists of points of the 3D space for which depth variations are small compared to the distance from the observer. Robust regression is applied to each depth layer in order to segment the latter into coherently moving regions. Finally, a combination stage is applied across all layers in order to come up with an integrated view of independent motion in the whole 3D scene. In contrast to other existing approaches for independent motion detection which are based on the ill-posed problem of optical flow computation, the proposed method relies on normal flow fields for both stereo and motion processing. Experimental results show the effectiveness and robustness of the proposed scheme, which is capable of discriminating independent 3D motion in scenes with large depth variations.
BibTeX:
@techreport{ArgyrosLourakisTrahaniasEtAl1996d,
  author = {Argyros, Antonis A and Lourakis, Manolis I A and Trahanias, Panos E and Orphanoudakis, Stelios C},
  title = {Independent 3D Motion Detection Through Robust Regression in Depth Layers},
  school = {FORTH-ICS},
  year = {1996},
  month = {February},
  number = {TR-159},
  url = {http://users.ics.forth.gr/ argyros/res_imd.html}
}
► A.A. Argyros and S.C. Orphanoudakis, "Load Redistribution Algorithms for Parallel Implementations of Intermediate Level Vision Tasks", FORTH-ICS, TR-48, 1992. [Abstract] [BibTeX] [PDF] [URL]
Abstract: Parallelism can be exploited to handle the enormous computational requirements of many vision applications. However, the computational power offered by multiprocessor architectures cannot be fully harnessed to achieve the desired speedup. This is primarily due to the unbalanced distribution of computational load among the processors of a parallel architecture. Furthermore, in parallel implementations of image analysis tasks, what constitutes computational load and the load balancing requirements of specific implementations are often difficult to define in a systematic way. In this paper, we consider the load balancing requirements of parallel implementations of intermediate level vision tasks on distributed memory parallel architectures. The computational characteristics of such tasks are briefly discussed and an appropriate definition of computational load is adopted. The primary implication of this definition for load balancing is that load entities to be redistributed are allowed to have nonuniform computational cost. An existing algorithm, which assumes uniform cost loads, and two modifications of this algorithm, which handle the nonuniform cost loads encountered in parallel implementations of intermediate level vision tasks, are described. These algorithms have been implemented on the iPSC/2 hyper-cube and their performance has been evaluated using simulated load conditions, as well as in the context of a simple object recognition system. Results on load balancing accuracy and total execution time are presented and discussed. Algorithmic performance has also been compared with the cases of optimal load distribution and no load redistribution. This work emphasizes the importance of understanding the requirements and difficulties of load redistribution in parallel image processing applications.
BibTeX:
@techreport{ArgyrosOrphanoudakis1992c,
  author = {Argyros, Antonis A and Orphanoudakis, Stelios C},
  title = {Load Redistribution Algorithms for Parallel Implementations of Intermediate Level Vision Tasks},
  school = {FORTH-ICS},
  year = {1992},
  number = {TR-48},
  address = {FORTH-ICS},
  url = {http://users.ics.forth.gr/ argyros},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/1992_07_tr048_forth_load_redistribution_in_vision.pdf}
}
► A.A. Argyros, "Load Redistribution Algorithms for Parallel Implementations of Intermediate Level Vision Tasks", M.Sc. Thesis, Computer Science Department, University of Crete, December 1992. [BibTeX] [DOI] [URL]
BibTeX:
@mastersthesis{Argyros1992a,
  author = {Argyros, Antonis A},
  title = {Load Redistribution Algorithms for Parallel Implementations of Intermediate Level Vision Tasks},
  school = {Computer Science Department, University of Crete},
  year = {1992},
  month = {December},
  address = {Heraklion, Crete, Greece},
  url = {http://users.ics.forth.gr/ argyros},
  doi = {http://elocus.lib.uoc.gr/dlib/8/9/0/metadata-dlib-1992argyros.tkl}
}
► A.A. Argyros and S.C. Orphanoudakis, "Load Redistribution Algorithms for Parallel Implementations of Intermediate Level Vision Tasks", In ERCIM Workshop on Parallel Architectures for Computer Vision, pp. 91-101, Hersonissos, Crete, Greece, October 1992. [BibTeX]
BibTeX:
@inproceedings{ArgyrosOrphanoudakis1992b,
  author = {Argyros, Antonis A and Orphanoudakis, Stelios C},
  title = {Load Redistribution Algorithms for Parallel Implementations of Intermediate Level Vision Tasks},
  booktitle = {ERCIM Workshop on Parallel Architectures for Computer Vision},
  year = {1992},
  month = {October},
  pages = {91--101},
  address = {Hersonissos, Crete, Greece}
}
► A.A. Argyros and S.C. Orphanoudakis, "Load Redistribution Algorithms for Parallel Implementations of Intermediate Level Vision Tasks", In Dartmouth Advanced Graduate Studies Symposium on Parallel Computing (DAGS/PC 1992), pp. 162-175, Dartmouth College, New Hampshire, USA, June 1992. [BibTeX] [PDF]
BibTeX:
@inproceedings{ArgyrosOrphanoudakis1992a,
  author = {Argyros, Antonis A and Orphanoudakis, Stelios C},
  title = {Load Redistribution Algorithms for Parallel Implementations of Intermediate Level Vision Tasks},
  booktitle = {Dartmouth Advanced Graduate Studies Symposium on Parallel Computing (DAGS/PC 1992)},
  year = {1992},
  month = {June},
  pages = {162--175},
  address = {Dartmouth College, New Hampshire, USA},
  pdflink = {http://users.ics.forth.gr/ argyros/mypapers/1992_07_tr048_forth_load_redistribution_in_vision.pdf}
}
► A. Damianakis, A.A. Argyros and S.C. Orphanoudakis, "Parallel Implementations of Image Analysis Tasks", In Panhellenic Conference on Informatics, Athens, Greece, May 1991. [BibTeX]
BibTeX:
@inproceedings{DamianakisArgyrosOrphanoudakis1991a,
  author = {Damianakis, Adam and Argyros, Antonis A and Orphanoudakis, Stelios C},
  title = {Parallel Implementations of Image Analysis Tasks},
  booktitle = {Panhellenic Conference on Informatics},
  year = {1991},
  month = {May},
  address = {Athens, Greece}
}