Abstract
In the general case, the recovery of a 3D scene from its 2D projection is indeterminate. Adding constraints typical of normal environments sometimes, however, allows unique solutions to be determined. This study is concerned with how monocular visual perception resolves the ambiguities in the 3D position of a target object in the presence of an extended background surface. Computer-generated images, shown in a wide-angle rear-projection display, produced a compelling perceptual impression of a 3D scene in which a regular array of widely-spaced square tiles formed a flat vertical plane slanted, around a vertical axis, relative to the frontal plane. On each trial, a target tile could be displaced from its regular array position, either left or right along the surface of the array plane, or perpendicularly to the plane, either in front of or behind it. Observers made two, three-alternative, forced-choice judgments: (1) whether the target was perceived to be to the left, right, or in the center of its regular position in the array and (2) whether the target was perceived to be in front of, behind, or on the array plane. Lateral and perpendicular displacements relative to the slanted array plane both produced changes in the size and shape of the projected target image as well as shifts in its lateral position. Nevertheless, the distinct combinations of these projective transformations, produced by the two types of displacement, were in principle sufficient to mathematically disambiguate them under the constraint that the target tile remained physically identical to the other tiles in the array. Observers' perceptual judgments, however, showed systematic errors suggesting that the perceived lateral and perpendicular target displacements interacted perceptually in ways inconsistent with this constraint and biased by the implied surface induced by the array of tiles.
Meeting abstract presented at VSS 2015