“…Numerous numerical algorithms on the optical ow estimation and its applications have been performed. They have clearly shown how the optical ow can be used to recover information about slant and tilt of surface elements, egomotion, shape information, time to collision, etc 31,32,30,34,33,29,28,38,50,24,37,49,27,9,40,41] Almost all these approaches use the classical brightness constancy assumption that relates the gradient of brightness to the components of the local ow to estimate. Because this problem is ill-posed, additional constraints are usually required.…”