Three dimensional computer graphics employing ray tracing to compute

Abstract

A method for rendering a three-dimensional image on a computer graphics display device involving the steps of providing a data base defining at least the geometry and reflectivity of light emitters and object in the scene and approximating surfaces of each object in the scene as patches in three dimensional space. Each patch is approximated as one or more elements defined by vertices. A source of irradiated light in the scene is selected and defined as a light source. Then, for each vertex, a form factor representing the fraction of light energy that arrives at the vertex from the source is determined by ray tracing from the vertex to the source. Radiosity is then determined at each vertex based on the form factors determined for each vertex. This process is repeated a selected number of times using a different light source each time. In this manner a plurality of radiosities are determined that collectively indicate the global illumination of the scene. The scene is then displayed based upon these radiosities.