Images from optical disks are read and processed later. Organization of the stereo system. In order to relate the coordinates of points in stereo images to points in 3-D, it is required to calibrate the cameras. Calibration is achieved by rotating the cameras inward so that their optical axes intersect at about the distance where the speaker will appear in front of the cameras. Coordinates of four non-coplanar points in the scene and their correspondences in the images are used to compute the calibration parameters.
Lens distortion is ignored.
The set up used to calibrate the stereo camera system. Right before speaking, an eye-safe laser line is swept over the speaker's face. The laser line is kept vertical during sweeping to maximize the correspondence accuracy. 3-D facial points obtained by matching laser points in stereo images are entered into a volumetric image to obtain a volumetric representation for the face right before speaking. This volumetric image contains information about the pose of the face of the speaker.