STEREO-MOTION COOPERATION AND THE USE OF MOTION DISPARITY IN THE VISUAL-PERCEPTION OF 3-D STRUCTURE

When an observer views a moving scene binocularly, both motion paralla x and binocular disparity provide depth information. In Experiments 1A -1C, we measured sensitivity to surface curvature when these depth cue s were available either individually or simultaneously. When the depth cues yielded comparable sensitivity to surface curvature, we found th at curvature detection was easier with the cues present simultaneously , rather than individually. For 2 of the 6 subjects, this effect was s tronger when the component of frontal translation of the surface was v ertical, rather than horizontal. No such anisotropy was found for the 4 other subjects. If a moving object is observed binocularly, the patt erns of optic flow are different on the left and right retinae. We hav e suggested elsewhere (Cornilleau-Peres & Droulez, in press) that this motion disparity might be used as a visual cue for the perception of a 3-D structure. Our model consisted in deriving binocular disparity f rom the left and right distributions of vertical velocities, rather th an from luminous intensities, as has been done in classical studies on stereoscopic vision. The model led to some predictions concerning the detection of surface curvature from motion disparity in the presence or absence of intensity-based disparity (classically termed binocular disparity). In a second set of experiments, we attempted to test these predictions, and we failed to validate our theoretical scheme from a physiological point of view.