An algorithm for optical flow estimation is presented, for the case of discrete-time motion of an uncalibrated camera through a rigid world. Unlike traditional optical flow approaches that impose smoothness constraints on the flow field, this algorithm assumes smoothness on the inverse depth map. The computation is based on differential measurements and estimates are computed within a multi-scale decomposition. Thus, the method is able to operate properly with large displacements (i.e., large velocities or low frame rates). Results are shown for a synthetic and a real sequence.