Using photometric files that represent actual light fixtures, a rendering can be prepared using radiosity. This is a simulation of the interplay of light between the various surfaces in a model. This can produce both a useful visualization of the appearance of the lighting in a space, and quantitative estimates of the light levels throughout the model. This technique works with both artificial lighting and daylight and is particularly useful in spaces that rely on indirect lighting.

This image is from a lighting study done for a new school cafeteria. The preliminary model showed a dark band on each side of the cafeteria where the indirect lights and the ceiling geometry did not throw enough light. A row of recessed lights was added to each side to correct the problem. This output provides a realistic, qualitative description of the lighting in a space.

This image is a false color image of the same space. The varying colors represent different light levels (on a logarithmic scale in this case) and provide a quantitative description of the lighting in the space.