Determining The Instantaneous Direction Of Motion From Optical Flow Generated By A Curvilinearly Moving Observer

A method is described capable of decomposing the optical flow into its rotational and translational components. The translational component is extracted implicitly by locating the focus of expansion associated with the translational component of the relative motion. The method is simple, relying on minimizing an (error) function of 3 parameters. As such, it can also be applied, without modification, in the case of noisy input information. Unlike the previous attempts at interpreting optical flow to obtain elements, the method uses only relationships between quantities on the projection plane. No 3D geometry is involved. Also outlined is a possible use of the method for the extraction of that part of the optical flow containing information about relative depth directly from the image intensity values, without extracting the "retinal" velocity vectors.