Automatic camera calibration based on robot calibration

MCIT (Multimedia Control Interface for Telerobotics) is an augmented reality system we are working on in our lab. MCIT sensing devices consist of a camera, allowing the operator an indirect view of a scene (real world), proprioceptive and exteroceptive sensors, allowing the building and updating of the 3D geometric database (3D DB) of the environment (virtual world). The virtual world is projected onto a video display terminal (VDT) Computer-generated and video images are superimposed. The man-machine interface functions deal mainly with on-line building of graphics aids to improve perception, updating the geometric database of the task site and video control of the robot. It allows the operator to perform a task level control of the robot. The superimposition of the real and virtual worlds is carried out through a calibration of the multi-sensor system. Within this system there is a direct connection between the video image of an object and its model in the geometric 3D DB. So the robot device can be controlled through the VDT. When the human operator points out an object onto the VDT, in actual fact he points it out in the 3D DB. This allows the programming of the robot with the video image of the robot's site; a task level video control of the robot. In order to improve the accuracy of the building and updating of the 3D geometric database, which are very important for the robot control, we present in this paper an accurate technique for automatic camera calibration and the results for two kinds of cameras.