Motion and depth from optical flow

Passive navigation of mobile robots is one of the challenging goals of machine vision. This note demonstrates the use of optical flow, which encodes the visual information in a sequence of time varying images [1], for the recovery of motion and the understanding of the three dimensional structure of the viewed scene. By using a modified version of an algorithm, which has recently been proposed to compute optical flow, it is possible to obtain dense and accurate estimates of the true 2D motion field. Then these estimates are used to recover the angular velocity of the viewed rigid objects. Finally it is shown that, when the camera translation is known, a coarse depth map of the scene can be extracted from the optical flow of real time varying images.