Precomputed Illuminance Composition for Real-Time Global Illumination

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 of 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. The sparse sampling of direct light also enables indirect lighting from many light sources and efficient progressive multi-bounce. Furthermore, any existing pipeline can be used for surfel lighting, enabling the use of all kinds of light sources. This also includes area lights which can be computed together with the first bounce indirect illumination of other light sources at no additional cost.