Correlation techniques for obtaining depth profiles from stereo pairs have been studied extensively yet continue to have problems with generality and computational efficiency. A new method is presented which develops the camera model constraints required to ensure that binocular disparity shifts only shift in the x direction. An optimal mapping algorithm is then applied which gives a globally optimal depth profile for a given line of the stereo pair. The algorithm performs well in cases which are difficult for correlation based algorithms namely, repetitive patterns, depth discontinuties and large, relatively featureless regions. With currently available IC chips this algorithm could be implemented in hardware to achieve video rate performance.