Realistic Generation and Real Time Animation of Images of the Human Colon

Abstract

A simulator has been built to teach doctors the skill of handling a flexible endoscope for gastrointestinal investigations. Trainees use a dummy endoscope in which the control actions are transduced into voltages and sensed by the computer. The simulator computes the position and viewing direction of the endoscope within an internal model of the human colon. Then a renderer draws the view, reproducing as far as possible what would be seen during a real colonoscopy. Since the system must generate at least ten frames per second for realistic animation, standard rendering techniques, such as ray tracing, could not be used. Consequently a new method was devised, based on identifying coherent regions along each scan line which can be rendered by table lookup. The method allows shaded Lambertian surfaces to be drawn at a frame rate of 15 per second, using modest computing resources. Although several approximations were required in the analysis, the computer images of the internal surfaces of the human colon present a high degree of visual realism.