An efficient cluster-based hierarchical progressive radiosity algorithm

Abstract

This paper describes a cluster-based hierarchical approach to energy transfer within the framework of a progressive radiosity algorithm. The clustering does not rely on the input geometry, but is performed on the basis of a local position in the scene for a pre-meshed scene model. The locality of the resulting clusters improves the accuracy of form factor calculations, and increases the number of possible high-level energy transfers between clusters within the imposed error bound. Limited refinement of the hierarchy of light interactions is supported without compromising the quality of shading when intermediate images are produced immediately upon user request. The algorithm performs well for complex scenes, and the growth of required data structures is linear with geometric complexity. The results of the experimental validation of the algorithm against measured real-world data show that calculation speed is reasonably traded for accuracy.

The authors would like to thank Oleg Okunev and Michael Cohen for reviewing the manuscript, as well as Koji Tsuchiya for help in collecting data describing the atrium and rendering of the Hurva Synagogue. Special thanks for helpful discussions and providing the measurement data go to Akira Fujimoto.