|Hierarchical Global Illumination by Using Cone Casts
Casting rays is a very common elementary operation in light simulation methods. We replace rays by cones to estimate a level of detail in a hierarchically represented scene.
This enables us to use only a part of the scene hierarchy to compute a full global illumination. Hence the performance and memory footprint become prop ortional to the image resolution and the metho d can b e used to render large out-of-core scenes.
In contrast to former cone casting methods we do not try to find an intersection between a cone and the scene. Instead we only trace the central ray and sample the cone interior sto chastically. This simplifies the intersection problem to rays where we use the cone radius for the level of detail estimation only. Whereas, reducing the radius towards zero leads to a standard ray tracing. Therefore it is possible to trade off correctness against performance.
Further we exploit the discretization of the scene to store intermediate results of diffuse illumination to increase the profit from recursive ray tracings. A novel light distribution pass also stores illumination directly, but generates artifacts yet.
Unsolved problems are a reliable reflection distribution for clustered scene geometry and the generation of caustics in the view-importance reduced scene.