Trinocular stereo for non-parallel configurations

The constraint of a third camera in stereo vision is a useful tool for reducing ambiguity in matching. Most of the systems using trinocular stereo to date however, have used configurations where the image planes of all three cameras are coplanar, or can be rectified to be so. We explore the computation of dense trinocular disparity maps for non-planar camera configurations which arise when cameras surround the object to be modeled. Our approach rectifies the cameras as two independent stereo pairs. We start with an exhaustive lookup scheme and then consider retaining only a list of N disparities per pixel with maximal correlation values for the right and left pairs. Experimental results and comparisons demonstrate that both methods reduce outliers over binocular stereo, and that the N-hypothesis system trades large lookup tables for somewhat lower density of valid matches