Radiance is a suite of programs for the analysis and visualization of lighting in design.
Input files specify the scene geometry, materials, luminaires,time, date and sky conditions (for daylight calculations). Calculated values include spectral radiance (ie. luminance + color), irradiance (illuminance + color) and glare indices. Simulation results may be displayed as color images, numerical values and contour plots.
The primary advantage of Radiance over simpler lighting calculation and rendering tools is that there are no 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.
Radiance is UNIX software -- if you are interested in PC software, go to the ADELINE page.