System and method of adjusting ray origins when shading vertices with rays

A REYES image rendering architecture is a system for computing computer animated video or images. The details of an exemplary REYES image rendering architecture are described in detail by Robert L. Cook, et al. in "The Reyes Image Rendering Architecture", Computer Graphics, vol. 21, no. 4, July 1987, which is incorporated herein by reference. When processed in conjunction with a REYES image rendering architecture compatible renderer (a "REYES renderer"), primitives represent objects that may be included in the computer animated video or images. These primitives are typically diced into polygonal meshes prior to being shaded and projected onto an image plane. After projecting the polygonal meshes onto the image plane, visible polygons are identified. More specifically, the polygons closest to defined elements of the image plane are identified. These elements may comprise infinitesimal points, lines, or areas on the image plane. Color values computed for vertices of the visible polygons are then used to compute color values for the image plane. The present invention is related to rendering computer animated video and/or images generally, and to adjusting the origins of rays cast for object-edge positions. The present invention includes identifying a location of a vertex positioned on a perimeter of an object defined in the object scene by a plurality of vertices. The plurality of vertices include the vertex positioned on the perimeter of the object. A shading position that corresponds to, but is offset from, the vertex is then established. A shading value is then computed for the vertex by reference to the shading position. The shading value may be computed, for example, by casting a ray from the shading position.