Inverse 3-D graphics: A metaphor for visual perception

Abstract

There are two key elements in defining the problem of visual perception. The first is that useful information about the world, such as the shape, material, illumination, and spatial relationships of objects, is encrypted in the image. Second, the encryption process, of going from a description of the world to an image, is not in general reversible. Any single source of image information is usually ambiguous about its causes in the scene. Seeing is the process of decoding the image information. 3-D computer graphics simulates the process of encrypting scene information into the image. By creating images from synthetic scenes, we can gain insights into the constraints used by the visual system to decode image information, and we can begin to bridge the gap between the simple images of the laboratory and complex natural scenes. Computer graphics modeling and animation tools provide the means to generate stills and animations that produce strong perceptual interpretations, yet are theoretically indeterminate. I will describe several illusions involving computer renderings and animations that illustrate the constraints human perception uses to solve ambiguity about material, shape, and depth.