A UNIFIED HIERARCHICAL ALGORITHM FOR GLOBAL ILLUMINATION WITH SCATTERING VOLUMES AND OBJECT CLUSTERS

This paper presents a new radiosity algorithm that allows the simultan eous computation of energy exchanges between surface elements, scatter ing volume distributions, and groups of surfaces, or object dusters, T he new technique is based on a hierarchical formulation of the zonal m ethod, and efficiently integrates volumes and surfaces, In particular no initial linking stage is needed, even for inhomogeneous volumes, th anks to the construction of a global spatial hierarchy, An analogy bet ween object clusters and scattering volumes results in a powerful clus tering radiosity algorithm, with no initial linking between surfaces a nd fast computation of average visibility information through a cluste r. We show that the accurate distribution of the energy emitted or rec eived at the duster level can produce even better results than isotrop ic clustering at a marginal cost, The resulting algorithm is fast and, more importantly, truly progressive as it allows the quick calculatio n of approximate solutions with a smooth convergence towards very accu rate simulations.