THE PERCEPTION OF SHAPE AND CURVEDNESS FROM BINOCULAR STEREOPSIS AND STRUCTURE-FROM-MOTION

The integration of binocular stereopsis and kinetic depth was measured for two distinct aspects of 3-D structure: (1) shape index, which is a measure of scale-independent structure, and (2) curvedness, which is a measure of scale-dependent structure. We found that motion contribu tes significantly more to judged shape index than it does to judged cu rvedness, and stereo contributes significantly more to judged curvedne ss than it does to judged shape index. This suggests that the differen ces in the relative contribution of motion and stereo reported here oc curred because these two sources do not equally specify the scale-depe ndent and scale-independent aspects of surface structure. Furthermore, these results seem to be inconsistent with integration models in whic h the different visual cues all initially contribute to the same singl e representation of 3-D structure.