THE USE OF OPTICAL-FLOW FOR ROAD NAVIGATION

This paper describes procedures for obtaining a reliable and dense opt ical how from image sequences taken by a television (TV) camera mounte d on a car moving in usual outdoor scenarios, The optical flow can be computed from these image sequences by using several techniques, Diffe rential techniques to compute the optical flow do not provide adequate results, because of a poor texture in images and the presence of shoc ks and vibrations experienced by the TV camera during image acquisitio n, By using correlation based techniques and by correcting the optical Bows for shocks and vibrations, useful sequences of optical flows can be obtained, When the car is moving along a flat road and the optical axis of the TV camera is parallel to the ground, the motion field is expected to be almost quadratic and have a specific structure, lis a c onsequence the egomotion can be estimated from this optical Bow and in formation on the speed and the angular velocity of the moving vehicle are obtained, By analyzing the optical Bow it is possible to recover a lso a coarse segmentation of the how, in which objects moving with a d ifferent speed are identified, By combining information from intensity edges a better localization of motion boundaries are obtained, These results suggest that the optical flow can be successfully used by a vi sion system for assisting a driver in a vehicle moving in usual street s and motorways.