Volumetric Vector-Based Representation for Indirect Illumination Caching

This paper introduces a caching technique based on a volumetric representation that captures low-frequency indirect illumination. This structure is intended for efficient storage and manipulation of illumination. It is based on a 3D grid that stores a fixed set of irradiance vectors. During preprocessing, this representation can be built using almost any existing global illumination software. During rendering, the indirect illumination within a voxel is interpolated from its associated irradiance vectors, and is used as additional local light sources. Compared with other techniques, the 3D vector-based representation of our technique offers increased robustness against local geometric variations of a scene. We thus demonstrate that it may be employed as an efficient and high-quality caching data structure for bidirectional rendering techniques such as particle tracing or photon mapping.