Investigations of Three-Dimensional Shape Perception for Telepresence Using Superquadric Primitives

Roger A. Browse and James C. Rodger

Abstract

Graphic displays for virtual environments and telerobotics require effective communication of the details of three-dimensional object shape. This paper presents empirical evidence on the relation between human perception and several properties of graphic shape depiction.

A series of experiments examined a three-dimensional shape discrimination task requiring judgments of superquadric volume primitives varying in shape within different rendering and display conditions. The displays were dynamic, with constant rotational motion. Over the series of experiments, the contributions of diffuse and specular shading, occluding contour, aspect ratio, and covarying size were evaluated.

The results revealed a consistent sensitivity to differences in superquadric shape parameters, which was surprisingly robust over rendering variations. One major finding was that the presence of specular highlights did not enhance shape discrimination performance beyond that observed for purely diffuse reflectance. Another was that contour information alone was sufficient to discriminate shape with considerable accuracy, but adding diffuse shading to the rendered surfaces did lead to marked improvements in performance. The results suggest strategies for optimizing interface properties where three-dimensional shape is a primary component of the display. They also support the use of superquadric primitives in situations where humans interact with shape display systems.