ACTIVE CAMERA CALIBRATION FOR A HEAD-EYE PLATFORM USING THE VARIABLE STATE-DIMENSION FILTER

This correspondence presents a new technique for calibrating a camera mounted on a controllable head/eye platform. It uses the trajectories of an arbitrary number of tracked corner features to improve the calib ration parameter estimates over time, utilizing a novel variable state dimension form of recursive filter. No special visual stimuli are req uired and no assumptions are made about the structure of the scene, ot her than that it is stationary relative to the head. The algorithm run s at 4 frames per second on a single Inmos T805 transputer, and is ful ly integrated into a real-time active vision system. Updated calibrati on parameters are regularly passed to the Vision modules that require them. Although the algorithm requires an initial estimate of camera fo cal length, results are presented from real experiments demonstrating that convergence is achieved for initial errors up to 50%.