Real Time Global Illumination Using Precomputed Illuminance Composition with Chrominance Compression
In this paper we present a new real time approach for indirect global illumination under dynamic lighting conditions. We use surfels to gather a sampling of the local illumination and propagate the light through the scene using a hierarchy and a set of precomputed light transport paths. The light is then aggregated into caches for lighting static and dynamic geometry. By using a spherical harmonics representation, caches preserve incident light directions to allow both diffuse and slightly glossy BRDFs for indirect lighting. We provide experimental results for up to eight bands of spherical harmonics to stress the limits of specular reflections. In addition, we apply a chrominance downsampling to reduce the memory overhead of the caches. The sparse sampling of illumination in surfels also enables indirect lighting from many light sources and an efficient progressive multi bounce implementation. Furthermore, any existing pipeline can be used for surfel lighting, facilitating the use of all kinds of light sources, including sky lights, without a large implementation effort. In addition to the general initial Meinl, F. Crytek Sponza (www.crytek.com) Persson, E. Saint Lazarus Church. CC BY 3.0 (www.humus.name)