Radiance uses a light-backwards Monte Carlo ray tracing method with irradiance caching for efficiency. A photon-mapping capability was recently added to handle caustics and difficult daylighting situations. The primary advantage of Radiance over simpler lighting calculation and rendering tools is that there are few limitations on the geometry or the materials that may be simulated. Radiance is used by architects and engineers to predict illumination, visual quality and appearance of innovative design spaces, and by researchers to evaluate new lighting and daylighting technologies. Advanced annual simulation capabilities are included as well.