Deducing Explicit from Implicit Visibility for Global Illumination with Antiradiance

The antiradiance method, a variant of radiosity, allows the computation of global illumination solutions without determining visibility between surface patches explicitly, unlike the original radiosity method. However, this method creates excessively many links between patches, since virtually all elements exchange positive and negative energy whose interplay replaces the visibility tests. In this paper we study how and if explicit visibility information can be recovered only by analyzing the link mesh to identify chains of links whose light transport cancels out. We describe heuristics to reduce the number of links by extracting visibility information, still without resorting to explicit visibility tests, e.g. using ray casting, and use that in combination with the remaining implicit visibility information for rendering. Further, to prevent the link mesh from growing excessively in large scenes in the beginning, we also propose a simple means to let graphic artists define blocking planes as a way to support our algorithm with coarse explicit visibility information. Lastly, we propose a simple yet efficient image-space approach for displaying radiosity solutions without any meshing for interpolation.