The following is an excerpt from the introduction to Greg Ward Larson et. al.'s book "Rendering with Radiance" (check our sources page):
Radiance was originally developed as a playground for exploring efficient techniques in ray-tracing. Early on, it acquired funding from the U.S. Department of Energy, and later from the Swiss federal government as a tool for energy-efficient lighting and daylighting design. Thus, an emphasis was placed on both practicality and physical accuracy. Later, as the software became more popular in the research and design communities and was applied to wider variety of problems, generality became a key issue.
... the purpose of Radiance is to produce lighting value predictions and physically accurate renderings of architectural spaces. The larger, implicit goal is to improve the design of such spaces through trial and error in simulation rather than trial and error in finished buildings. A side effect of producing a physically-accurate rendering system that is well suited to real-world problems is that the renderings tend to be highly realistic, and although this may attract some people to the software, photo-realism is not the primary mission; photo-accuracy is.
(End of book citation)
The result of the many years of work Greg Ward Larson put into the development of Radiance is a package of over 100 unix command line tools, supplemented with a small number of interactive programs written for the unix X11 windowing standard.
This approach gives an extremely powerful and highly flexible software system into the hand of the expert. At the same time, it piles up almost unscalable obstacles for the architect or lighting designer, who need to concentrate on their own field of expertise, and cannot afford to become computer cracks just to do the calculations they need for their job.
This is the point where Rayfront comes into the picture. We have decided to bring the lighting simulation power of the underlying Radiance system to the normal desktop user.