Visual Odometry based on Transitivity Error Analysis in Disparity Space - A Third-eye Approach

Accurate estimation of ego-motion heavily relies on correct point correspondences in the context of visual odometry. In order to ensure a metric reconstruction of camera motion, we can refer to the 3D structure of the scene. In this paper we present an indicator for evaluating the accuracy of stereo-based 3D point measurements as well as for filtering out low-confidence correspondences for ego-motion estimation. In a typical binocular system, the left and right images are matched to produce a disparity map. For a trinocular system, however, the map can be derived indirectly via disparity maps of both cameras with respect to the third camera. The difference between an explicitly matched disparity map and its indirect construction defines a transitivity error in disparity space (TED). We evaluate the effectiveness of TED from different perspectives, using a trinocular vehicle-mounted vision system. Results presented in 3D Euclidean space, or in 2D images show improvements of more than 7.5%, indicating that, by taking TED into account, more consistency is ensured for ego-motion estimation.