Global Diffuse Illumination with Polygonal Light Sources

We present an object-space algorithm for global illumination of polygonal scenes containing diffuse area light sources. Our method works within a progressive-refinement radiosity framework. Starting with a minimal scene mesh, we subdivide elements along shadow boundaries and where otherwise needed to capture intensity gradations accurately. Intensities at mesh points are computed by a method that calculates light source visibility analytically, producing exact values for primary light sources and good approximations for secondary sources. The shaded polygon mesh resulting from our algorithm lacks several artifacts common to radiosity algorithms and accurately reproduces the illumination phenomena modeled. CR Categories and Subject Descriptors: I.3.3 [Computer Graphics]: Picture/Image Generation--Display Algorithms. I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism. General Terms: Algorithms. Additional Key Words and Phrases: Binary Space Partitioning (BSP), computation..