The system design for GALATEA,an interactive real-time computer graphics system for movie and video analysis

The extraction of information from movie film and videotape has always been a very tedious process. Yet the usefulness of these media in biomedical research, behavioral science, industrial testing, etc., is apparent. We are developing a system, GALATEA, for the rapid extraction of data from film or video using interactive graphics. The key aspects of GALATEA are: the user indicates what features are of interest using an x, y digitizing pen. These pen positions are the only data the system sees, so that full digital image encoding is avoided. The user can trace the features while the film runs (frame-by-frame analysis is not necessary). The user has constant feedback in the form of an animated, computer-generated movie (Kinegram), overlaid on the original film image and running synchronously with it. It is this kinetic feedback of the data entered that makes the system efficient. Structured programming, real-time programming techniques, data structures for time-dependent pictures and dynamical graphics ‘tools’ are covered. A detailed discussion is given of Slippage or soft degradation in real-time systems under fluctuating load conditions.