Stereoscopic matching, eye position, and absolute depth

The viewing system parameters (in particular the mutual orientation of the coordinate frames fixed respectively to the left and right projection surface) probably have to be explicitly incorporated into solutions to the stereoscopic-matching problem in binocular vision. An algorithm for computing the relative orientation of the two directions of gaze from purely visual information without a prior solution to the correspondence problem is outlined. The availability of an algorithm of this sort seems to be a precondition for any stereoscopic-matching process that uses the epipolar constraint. It is further argued that fixation of objects in the near space requires integration of the results of stereoscopic matching over eye movements, and that this requirement puts rather tight restrictions on the possible form of representing the results of stereoscopic processing.