Multiple reference octrees for a GPU photon mapping and irradiance caching

This paper introduces an efficient and simple algorithm for constructing Multiple Reference (MR) octrees on a GPU in application to Photon Mapping and Irradiance Caching techniques. Although MR-octrees are hierarchical structures, we successfully ignore their hierarchical nature and present an approach with plain construction, compact data layout and stack-less traversal. Our algorithm uses only 2 parallel primitives (parallel append and parallel sort) and can be expressed in several lines of pseudo-code.