Abstract
Recently many researchers have been trying to display natural phenomena such as clouds, ocean waves, and flames using computer graphics. This paper proposes a fast method for generating images of clouds. Since clouds consist of particles with a high albedo, multiple scattering cannot be ignored. In our method, the density distribution of clouds is expressed by sets of metaballs. A metaball is a sphere and a density distribution is defined inside it. Multiple scattering is taken into account by computing the energy transfer between metaballs. To reduce the computation time, metaballs are grouped into a hierarchical structure, and graphics hardware is utilized. The proposed method is applied to creating images of outdoor scenes to demonstrate its usefulness.
