I suggest taking a look at Physically Based Rendering [1]. It goes through an advanced rendering system in a literate coding style. That is, the physical explanations are interspersed with the code of an open source renderer [2]. I'm not sure how it compares with this Disney renderer, but it should go a long way towards demystifying how these things work.

1. http://www.amazon.com/Physically-Based-Rendering-Second-Edit...

2. http://www.pbrt.org/

If you're interested in ray/path tracing or photorealistic rendering at all I would seriously recommend Physically Based Rendering[1]. It's probably one of the most satisfying book purchases I've made. The authors go through every aspect of implementing a quality path tracer: image sampling, surface shading models, statistics and integration methods, intersection testing and acceleration and more. It's an absolute treasure trove of information. (Be prepared to do a lot of math.)

[1] http://www.amazon.com/Physically-Based-Rendering-Second-Impl...

Here are few examples of great 1000+ pages books with lots of code. Though reading them is much more effort than reading a self-help book: http://www.amazon.com/Programming-Environment-Addison-Wesley... http://www.amazon.com/TCP-IP-Illustrated-Implementation-Vol/... http://www.amazon.com/Physically-Based-Rendering-Second-Edit...

"Physically based rendering" have a second newer edition: http://www.amazon.com/Physically-Based-Rendering-Second-Edit...