Radiance Maps: An Image-Based Approach to Global Illumination

We present a new image-based approach to global illumination that is designed to explicitly make use of coherence in the radiance field of a scene. The approach builds on recently developed ideas from image-based rendering in order to reuse previously computed geometric and illumination information as far as possible. The algorithm consists of a hierarchy of three methods, each taking advantage of a different coherence pattern in the radiance field. At the top level, we sample primary layered-depth radiance maps of the environment, thereby abstracting from the exact geometry of the scene. In the intermediate level, coherence in ray-space is exploited in order to derive new radiance maps by reprojection from primary maps. At the lowest level, gradient information is used to spatially interpolate smooth irradiance contributions, handling non-smooth contributions separately. Missing or uncertain information in lower levels is handled by resampling the environment, and feeding these sample..