The Motion Coherence Theory

Tliere are a number of important phenom- ena in motion perception involving colicrcnce. Examples include motion capture and motion cooperativity. We propose a theoretical model, called the motion coherence tlieory, that gives a possible explanation for these effects (Yuille and Grzywacz, 1988a,b). In this framework, the aperture problem can also be thought of as a problem of coherence and given a similar explanation. We propose the concept of a velocity field dcfined everywhere in the image, even where there is no explicit motion information available. Through a cost function, tlie model imposes smoothness on the velocity field in a more general way than previous theories. In this paper, we provide a de- tailed theoretical analysis of the motion coherence theory. We discuss its relations with previous theories and show that some of t1ic.m arc approximations to it. A sccorid pa- per (Grzywacz, Smith, and Yuillc, 1088) provides exten- sions and cletnilcd comparisons to psychophysical plienom- cna. Tlic theory applies to both short-range and long- range motion. It places them in the same computational framework aiid provides a way to define interactions be- twcr:11 the two 1)roccsses.