This document describes rayshade in enough detail to enable the technical-minded to sit down and render some images. In its current form, it is truly a draft, and even then more of a reference manual than a proper user's guide.
This document does not provide any kind of thorough introduction to the basics of computer graphics or ray tracing. There are many other excellent sources for this kind of information. The technical and coding details of rayshade and its libraries will be documented elsewhere.