Robust ego-motion estimation

This paper aims to develop a simple algorithm for determining the direction of ego-motion of a monocular observer in a static environment. Rather than returning a single direction the algorithm returns a set of motion directions known to contain the true direct tion. Translational motion can be arbitrary. The algorithm is based on one invented by Horn and Weldon [1]. It uses only normal components of optical flow at discrete image locations and is only intended to function when the the contribution of rotation to the apparent motion is small. The algorithm uses the fact that imaged points must be at some positive distance from the viewer. No implicit assumptions are made about the scene being viewed. The algorithm is illustrated on an artificially generated set of normal components. It is then tested on a real image sequence. By comparison with [1], this paper develops the idea of introducing rotation tolerance at the expense of accuracy of ego-motion determination. An analysis of the shape of the resulting set of possible motion directions is given.