Direct computation of the focus of expansion from velocity field measurements

Abstract

A new method for computing the direction of translational motion (focus of expansion) of a moving observer (or camera) in a stationary environment is proposed. The method applied simple 1D search directly to velocity field measurements of the changing image, for cases of general motion and constrained motion. In the case of general motion, the velocity field is derotated to cancel the velocity of the observed point at the image origin. In principle, a single moving closed contour which encircles the origin is sufficient to recover the focus of expansion. In practice, additional velocity measurements in the image may be incorporated in the computation, for improved robustness in the face of image noise and velocity field inaccuracies.<>