OCCLUSION, TRANSPARENCY, AND STEREOPSIS - A NEW EXPLANATION FOR STEREO CAPTURE

Stereo capture occurs when a regular pattern of repeating elements wit h zero disparity is superimposed on a disparate subjective figure. The elements enclosed within the subjective contours, but not those outsi de them, are perceptually captured and pulled on the same depth plane of the disparate figure. The phenomenon has been interpreted as the re sult either of a spreading of disparity signals from the subjective fi gure or of the attribution of the depth of certain salient image featu res to the finer texture elements enclosed in them. We suggest here th at, instead, the fact that stereo capture is limited to the texture el ements lying within the boundaries of the subjective figure is simply due to ambiguous occlusion information at the monocular level. When th e texture elements occlude the inducers of the subjective figure as we ll, the elements lying outside the boundaries of the subjective figure are also captured. We propose that stereo capture arises as the solut ion to a conflict between information provided by retinal disparity an d occlusion, and show how this effect is related to other previously o bserved phenomena of conflicting cues to depth.