Perceptually‐Driven Radiosity

Abstract

We present a new approach to radiosity simulation that uses perceptually‐based measures to control the generation of view‐independent radiosity solutions. This enables computational effort to be moved away from areas that are deemed to have a visually insignificant effect on the solution's appearance, into those that are more noticeable. We achieve this with an a‐priori estimate of the real‐world adaptation luminance, and use a tone‐reproduction operator to transform luminance values to display colours during the solution process. The distance between two colours in a perceptually‐uniform colour space is then used as a numerical measure of their perceived difference. We describe an oracle that stops patch refinement once the difference between successive levels of elements becomes perceptually unnoticeable. We also show how the perceived importance of any potential shadow falling across a receiving element can be determined. This is then used to control the number of rays that are cast during visibility computations, giving reductions of almost 93% in the total number of rays required for a solution without any significant loss in image quality. Finally, we discuss how perceptual knowledge can be used to optimise the element mesh for faster interactive display and to save memory during computation.