Computation of ego-motion using vertical cue

This paper describes the development and implementation of some layers of a line-segment-based module to recover ego motion while building a 3D map of the environment in which the absolute vertical is taken into account. We use a monocular sequence of images and 2D-line segments in this sequence. The proposed method reduces the disparity between two frames in such a way that 3D vision is simplified. In particular, the correspondence problem is simplified. Moreover, a estimation of the 3D rotation is provided. Using the vertical as a basic cue for 3D-orientation tremendously simplifies and improves the structure from motion paradigm, but the usual equations have to be worked out in a different way. An approach which combines ecological hypotheses and general rigid motion equations is presented, and the equations are derived and discussed in the case of small rigid motions. Algorithms, based on the minimization of theMahalanobis distance between two estimates, are given and their implementations discussed.