Papers by Mohamed Abdelkader
This paper presents a real-time system for detecting and tracking humans from mobile vehicles. Th... more This paper presents a real-time system for detecting and tracking humans from mobile vehicles. The system integrates human detection and tracking algorithms and employs depth information obtained from a stereo vision system. Depth information is used to limit the search space of the detector. We also present a simpler and faster variant of the popular Adaboost human detector. Experimental results demonstrate that integrating depth information vastly reduces the false detection rate compared with detection without stereo. Also, we show that integrating stereo enables the detection and tracking subsystem to operate in real-time.
We present a method for characterizing human activities using 3D deformable shape models. The mot... more We present a method for characterizing human activities using 3D deformable shape models. The motion trajectories of points extracted from objects involved in the activity are used to build models for each activity, and these models are used for classification and detection of unusual activities. The deformable models are learnt using the factorization theorem for nonrigid 3D models. We present a theory for characterizing the degree of deformation in the 3D models from a sequence of tracked observations. This degree, termed as deformation index (DI), is used as an input to the 3D model estimation process. We study the special case of ground plane activities in detail because of its importance in video surveillance applications. We present results of our activity modeling approach using videos of both high-resolution single individual activities and ground plane surveillance activities.
Computer Vision and Image Understanding, 2011
This paper addresses the problem of recognizing human gestures from videos using models that are ... more This paper addresses the problem of recognizing human gestures from videos using models that are built from the Riemannian geometry of shape spaces. We represent a human gesture as a temporal sequence of human poses, each characterized by a contour of the associated human silhouette. The shape of a contour is viewed as a point on the shape space of closed curves and, hence, each gesture is characterized and modeled as a trajectory on this shape space. We propose two approaches for modeling these trajectories. In the first template-based approach, we use dynamic time warping (DTW) to align the different trajectories using elastic geodesic distances on the shape space. The gesture templates are then calculated by averaging the aligned trajectories. In the second approach, we use a graphical model approach similar to an exemplar-based hidden Markov model, where we cluster the gesture shapes on the shape space, and build non-parametric statistical models to capture the variations within each cluster. We model each gesture as a Markov model of transitions between these clusters. To evaluate the proposed approaches, an extensive set of experiments was performed using two different data sets representing gesture and action recognition applications.
Eurasip Journal on Image and Video Processing, 2008
We present a method for characterizing human activities using 3D deformable shape models. The mot... more We present a method for characterizing human activities using 3D deformable shape models. The motion trajectories of points extracted from objects involved in the activity are used to build models for each activity, and these models are used for classification and detection of unusual activities. The deformable models are learnt using the factorization theorem for nonrigid 3D models. We present a theory for characterizing the degree of deformation in the 3D models from a sequence of tracked observations. This degree, termed as deformation index (DI), is used as an input to the 3D model estimation process. We study the special case of ground plane activities in detail because of its importance in video surveillance applications. We present results of our activity modeling approach using videos of both high-resolution single individual activities and ground plane surveillance activities.
frames. The systems was tested on a large ground-truthed data set containing hundreds of color an... more frames. The systems was tested on a large ground-truthed data set containing hundreds of color and FLIR image sequences. A performance evaluation for the system was performed and the average evaluation results are reported in this paper.
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Papers by Mohamed Abdelkader