Estimating Stereo Disparities
An interesting practical and theoretical problem is putting bounds on how much computation one needs to find the stereo-disparity between two narrow-angle stereo scenes. By narrow angle I mean situations wherein the angle subtended by the eyes is a very few degrees: the kind of correlation-disparity method discussed here probably isn't applicable to the wide-angle stereo we'll usually use for scene-analysis in the Project. The method we consider is to find the local maximum of local correlation between the left and right scenes, over a range of displacements along the eye-eye axis. Obviously this is a simple-minded method that will fail in certain situations: here we are not interested in bad cases so much as in getting estimates of the minimal computation in the favorable situations. A correlation can be considered as a properly-normalized sum of pairwise products of intensifies (or other surface functions). The correlation, for each disparity d, is obtained by using pairs that are d units apart in visual angle, referred to a standard azimuth scale in each eye. One can imagine a scheme in which the pairs are all different in the retinas.