A catadioptric sensor with multiple viewpoints

An estimation of distance (range) over a large surrounding area is crucial in mobile robotics. A solution is proposed here in the form of an omnidirectional stereo apparatus with two catadioptric sensors in a vertical coaxial arrangement. The coaxial stereo requires very simple matching since the epipolar lines are the radial lines of identical orientations in both omnidirectional images. The radial matching is supported by a novel polar edge finder which uses discrete cosine transform and returns image gradients expressed in polar coordinates.