Catadioptric stereo using planar mirrors

By using mirror reflections of a scene, stereo images can be captured with a single camera (catadioptric stereo). In addition to simplifying data acqu isition single camera stereo provides both geometric and radiometric advant ages over traditional two camera stereo. In this paper, we discuss the geom etry and calibration of catadioptric stereo with two planar mirrors. In par ticular, we will show that the relative orientation of a catadioptric stere o rig is restricted to the class of planar motions thus reducing the number of external calibration parameters from 6 to 5. Next we derive the epipola r geometry for catadioptric stereo and show that it has 6 degrees of freedo m rather than 7 for traditional stereo. Furthermore, we show how focal leng th can be recovered from a single catadioptric image solely from a set of s tereo correspondences. To test the accuracy of the calibration we present a comparison to Tsai camera calibration and we measure the quality of Euclid ean reconstruction. In addition, we will describe a real-time system which demonstrates the viability of stereo with mirrors as an alternative to trad itional two camera stereo.