Event Location: NSH 1305
Bio: Jim Rehg is a Professor in the School of Interactive Computing at the Georgia Institute of Technology. He is co-Director of the Computational Perception Lab and Associate Director of Research in the Center for Robotics and Intelligent Machines. He received his Ph.D. from CMU in 1995 and worked at the Cambridge Research Lab of DEC (and then Compaq) from 1995-2001, where he managed the computer vision research group. His research interests include computer vision, robotics, machine learning, and computer graphics. He recently served as the general co-chair for CVPR 2009 in Miami.

Abstract: A basic goal of video understanding is the organization of video data into sets of events with associated temporal dependencies. For example, a soccer goal could be explained using a vocabulary of events such as passing, dribbling, tackling, etc. In describing the dependencies between events it is natural to invoke the concept of causality, but previous attempts to perform causal reasoning in video analysis have been limited to special cases, such as sporting events or naïve physics, where strong domain models are available. In this talk I will describe a novel, data-driven approach to the analysis of causality in video. The key to our approach is the representation of low-level visual events as the output of a multivariate point process, and the use of a nonparametric formulation of temporal causality to group event data into interacting subsets. This grouping process differs from standard motion segmentation methods in that it exploits the temporal structure in video over extended time scales. We apply our method to the analysis of complex social interactions in video. Specifically, we address the categorization and retrieval of social games between parents and children from unstructured video collections. This application is part of a larger effort in using computer vision technologies to support the detection, treatment, and understanding of developmental disorders such as autism.

This is joint work with Karthir Prabhakar, Sangmin Oh, Ping Wang, and Gregory Abowd