Handling dynamic changes in hierarchical radiosity through interaction meshes

The paper describes a radiosity method well suited to dynamic changes while requiring less memory compared to classical hierarchical radiosity. Our method relies on the concept of interaction meshes and does not need any computation of links between patches. The light originating at emitters and arriving at a receiving input surface is stored on separate meshes, each one corresponding to an emitter-receiver pair. These meshes are called interaction meshes and facilitate the handling of dynamic changes since for each input surface the surfaces illuminating it can be determined very quickly. The second advantage of the method is the use of a refinement criterion based on the comparison between the illuminances (illuminance is a photometric quantity equivalent to irradiance) over the receiving surfaces reconstructed from the interaction meshes. This criterion makes possible the use of artificial and natural lighting. Finally, this meshing technique is well suited to multigridding resolution systems for which the interaction meshes are not refined but recomputed at each iteration without cumulating error due to earlier iterations