Disambiguation of Objects by Stereopsis and Motion Cues

Abstract

One of the major tasks faced by organisms in a complex environment is disambiguating the objects in that environment from their backgrounds and from each other. The task is already challenging when there are a few objects in view with multi-faceted surfaces covered with multicolored patterns and lit with varying degrees of light and shadow. This might be exemplified by a scene of bathers in multicolored swimwear on the beach. But the disambiguation becomes nearly impossible when the scene is a deeply three-dimensional one of foliage high in the trees of a thick forest. When primates first adopted such an arboreal habitat, they were faced with the task of locomotion through this three-dimensional realm of branches heavily masked by a veil of leaves. The stakes for disambiguating the true distances from tree to tree were high; the price of failure was to drop many meters onto a ground inhabited by carnivorous beasts.