I second that a major rewrite is definitely needed; that would be quite admirable of you if you have the time!  I would strongly suggest that you look at the German Wikipedia page on Raytracing (linked at the top).  The article is very well put together, and I think it correctly focuses more on the ray-tracing aspect as opposed to the more general physically-based rendering (which of course relies nearly exclusivly on ray tracing, but is certainly a broader term).