EURASIP Journal on Image and Video Processing
Volume 2008 (2008), Article ID 347050, 16 pages
doi:10.1155/2008/347050
Research Article
Activity Representation Using 3D Shape Models
1Department of Electrical and Computer Engineering and Center for Automation Research, UMIACS, University of Maryland, College Park, MD 20742, USA
2Department of Electrical Engineering, University of California, Riverside, CA 92521, USA
3Siemens Corporate Research, Princeton, NJ 08540, USA
Received 1 February 2007; Revised 9 July 2007; Accepted 25 November 2007
Academic Editor: Maja Pantic
Copyright © 2008 Mohamed F. Abdelkader et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
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.