Direct illuminance caching: a way to enhance the performance of RADIANCE

Abstract

The RADIANCE lighting simulation software suite has proven itself a valuable means of producing visualizations and enabling analysis of all kinds of lighting tasks. One of its key features is the accurate calculation of the indirect light component by hemisphere sampling throughout the scene. Currently, there is a certain amount of redundancy within the algorithm. The performance reduction caused by this increases strongly with the number of light sources and becomes significant when more than five sources are present. A method for circumventing this redundancy is presented and its potential for considerably reducing rendering time is shown. The limitations of the new method are discussed and guidelines for its use are given, followed by some remarks on image generation for presentation purposes. The source code of the additional module is provided for downloading.