Responsive Body Tracking	an interactive installation by Michael Hoch, Daniel Thalmann, Soraia Raupp Musse, and Fabien Garat shown at "The Anagrammatical Body - the body and its medial construction" june - oct at ZKM '2000. An interactive environment where groups of real people get in contact to groups of virtual people. A video-based tracking system monitors the visitors movements and triggers reactions of virtual humans. This installation is based on the general notion that people should experience the sense of presence in a virtual space through movements as much as through visual or acoustic impressions. As social beings people are necessarily aware of their (local) position in group situations and they experience the physical space and the social climate of a group situation by simultaneously watching and moving around. By entering the interaction space, differing modes of group modalities of interaction and differing linkage between real and the virtual crowds can be explored. Based on events in real space, that get recognized using the vision system, corresponding events in virtual space are triggered by guiding and interacting with the virtual crowds. To monitor the movements of up to five people in real space an infrared camera mounted on the ceiling above the interaction space is used. The movements of the people in space and over time are tracked by calculating the position, the direction of movement and the speed of movement of each individual. The focus of the analysis is put on the movement in space with respect to the virtual world and the inter relationship of people in the interaction area, which itself creates very complex patterns. These patterns are used to recognize 12 different events, like entering, exit, group_formed, group_deleted, movements and fast movements, and when all people form a line or a circle. A small window shows each tracked visitor as a cylinder and the detected events. movie> byebye.mpg (19 MB)   Credits> Tracking Interface: Michael Hoch, ZKM | Institute for Visual Media Virtual Crowd Control: Daniel Thalman, Soraia Raupp Musse and Fabien Garat Swiss federal Institute of Technology - Computer Graphics Lab Virtual Human software provided by EPFL, Computer Grphics Lab, Lausanne, Switzerland and University of Geneva, MIRALab, Switzerland in the framework of the eRENA ESPRIT Project.