Adaptive mesh generation for global diffuse illumination

Rapid developments in the design of algorithms for rendering globally illuminated scenes have taken place in the past five years. Net energy methods such as the hemicube and other radiosity algorithms have become very effective at computing the energy balance for scenes containing diffusely reflecting objects. Such methods first break up a scene description into a relatively large number of elements, or possibly several levels of elements. Energy transfers among these elements are then determined using a variety of means. While much progress has been made in the design of energy transfer algorithms, little or no attention has been paid to the proper generation of the mesh of surface elements. This paper presents a technique for adaptively creating a mesh of surface elements as the energy transfers are computed. The method allows large numbers of small elements to be placed at parts of the scene where the most active energy transfers occur without requiring that other parts of the scene be needlessly subdivided to the same degree. As a result, the computational effort in the energy transfer computations can be concentrated where it has the most effect.