Stereo Ranging with Verging Cameras

Abstract

A method of computing absolute range from stereo disparities by using verging cameras is presented. The approach differs from others by concentrating, through both analysis and experiment, on the effects caused by convergence, rather than on the general camera calibration problem. To compute stereo disparities, linear image features are extracted and matched using a hypothesize-and-verify method. To compute range, the relationship between object distance, vergence angle, and disparity is derived. Experimental results show the precision of the range computation, excluding mistaken matches, to be approximately 5% for object distances up to three meters and a baseline distance of 13 cm. Including mistaken matches results in performance that is an order of magnitude worse, leading the authors to suggest methods to identify and model them.