hierarchical caustic maps
Interactive applications typically rely on local models for lighting, occasionally augmented by GPU-friendly methods for approximating global illumination. Caustic mapping approximates the specular focusing of light using a light-space image, akin to a shadow map, which is projected onto the scene during final rendering. Unfortunately, existing caustic map implementations must choose between quality and speed. Quickly generated maps use few photons and look extremely blurry, while sharper maps created from millions of photons only render at a few frames per second. This paper introduces a number of hierarchical enhancements to caustic mapping that allow real-time rendering with high quality caustic maps, even when using maps from multiple light sources. These techniques utilize the geometry processing stage of recent GPUs to avoid processing every photon and to render a pyramidal caustic map that allows photon splats of varying diameters without the increased costs inherent in rasterizing large splats.
caustics interactive rendering hardware