Effects of Optic-Flow Density on the Metric Estimation of Rotation and Expansion

Abstract

Optic flow generated by rigid surface patches can be decomposed into four elementary motion types. We have shown that the human visual system can metrically estimate two of these motion types, rotation and expansion, by angular velocity and rate of expansion respectively. However, this contradicts previous work that reported linear velocity to be the parameter estimated. This discrepancy was caused by a difference in experimental methods. Experimental evidence shows that the visual system uses a different motion parameter based on the amount of motion information available. We've modeled this systematic switchover in information utilized in a probabilistic manner. Specifically, low motion information stimuli have a higher probability of being estimated by linear velocity than high motion information stimuli