Practical global illumination with irradiance caching

Since its invention 20 years ago, irradiance caching has been successfully used to accelerate global illumination computation in the Radiance lighting simulation system. Its widespread use had to wait until computers became fast enough to consider global illumination in production rendering. Since then, its use is ubiquitous. Virtually all commercial and open-source rendering software base the global illumination computation upon irradiance caching. Although elegant and powerful, the algorithm often fails to produce artifact-free images. Unfortunately, practical information on implementing the algorithm is scarce.