A ROBUST ALGORITHM FOR OPTICAL-FLOW ESTIMATION

Most of the existing methods for optical how estimation are based on a constraint equation which is defined for each image pixel. This class of algorithms is usually called gradient-based. Due to the structure of the constraint equation, the problem is ill-posed, thus some soluti ons based on regularization have been proposed in the past. On the con trary, if other constraint equations can be found for the pixel under consideration or in its immediate neighborhood, the problem is not ill -posed and a solution can be found by solving determined or over-deter mined systems of equations. Following this reasoning, several algorith ms for evaluating the optical how have been proposed in the literature . Most of these over-determined systems of equations are solved by usi ng least-squares techniques. In this paper, a new approach is presente d in order to eliminate, or strongly reduce, the drawbacks of least-sq uares and regularization-based techniques. This is based on a modified version of the Combinatorial Hough Transform. A comparison is made be tween the results obtained with the new approach and those produced by the classical least-squares and regularization-based techniques. (C) 1995 Academic Press, Inc.