Theoretical and experimental performance of a general stereo vision system

Traditional stereo ranging equations are based on the mathematics of similar triangles. This paper derives stereo ranging and resolution equations based on a general and flexible two-dimensional geometry. These equations include more degrees of freedom than the similar triangles approach, thereby allowing for more tolerance in developing a stereo system. They also provide an in-depth analysis of the effects of calibration errors in a stereo system. The theoretical performance prediction of a stereo system, based on an error of one pixel, is also given. A prototype stereo system has been developed to experimentally measure the range to a target. The theoretical predictions were compared to the experimental results. In total, 317 range measurements were taken at seven distinct baselines using three lenses of different focal lengths. The mean percent range error of these measurements is---0.65% with a standard deviation of 2.7%. The major limiting factor in the ability of a stereo system to measure range accurately is the minimum disparity associated with the particular stereo system. Reducing the minimum disparity, either through hardware or software techniques, can greatly improve the performance of the stereo system.