We introduce a new set of techniques for coherent out-of-core point-based global illumination and ambient occlusion. As described in [Christensen 2008], point-based global illumination (PBGI) operates on a dense point representation of the scene. Points are diffusely shaded and are roughly distributed according to a micropolygon tessellation. An octree is constructed over the points, where each octree node describes the light reflected from
the corresponding cluster of points to any direction. The reflected radiance is stored as spherical harmonics coefficients to compactly capture directional variation. After the octree has been constructed, each micropolygon is shaded by first selecting a set of octree nodes that define a suitable level of detail, and then accumulating the radiance stored in these nodes using a cube rasterizer.

Research Paper for Coherent Out-of-Core Point-Based Global Illumination