Apparatus and method for estimating reflected radiance under complex distant illumination

摘要

An apparatus and method for estimating reflected radiance under complex distant illumination are described. In one embodiment, an importance sampling estimator is used with a novel piecewise constant importance function that effectively concentrates ray samples where energy is likely to be found. To properly account for the effects of a visibility term in the shading calculation, in one embodiment, a shadow cache is provided which caches information indicating ray directions that are occluded or unoccluded from a point in space. Accordingly, by concentrating hemispheric samples where the light source is likely to be strongest, a reflected radiance integral is efficiently computed and estimated in a real-world lighting situation.