Distance perception mediated through nested contact relations among surfaces.

In complex natural scenes, objects at different spatial locations can usually be related to each other through nested contact relations among adjoining surfaces. Our research asks how well human observers, under monocular static viewing conditions, are able to utilize this information in distance perception. We present computer-generated naturalistic scenes of a cube resting on a platform, which is in turn resting on the ground. Observers adjust the location of a marker on the ground to equal the perceived distance of the cube. We find that (1) perceived distance of the cube varies appropriately as the perceived location of contact between the platform and the ground varies; (2) variability increases systematically as the relating surfaces move apart; and (3) certain local edge alignments allow precise propagation of distance information. These results demonstrate considerable efficiency in the mediation of distance perception through nested contact relations among surfaces.