Physically-Based Rendering

Dielectrics with Beer's Law.

Dielectrics and Beer’s Law are now integrated into the materials and environment frameworks. In the picture above the indices of refraction increase from left to right.

Reflection functions

I have been experimenting with BRDFs lately.

In the picture above, from left to right: Oren Nayar, Torrance-Sparrow with different roughness, and smooth dielectrics.

I am investigating how to represent materials in the core engine. Obviously it should be as physically correct as possible.

Here is my current wish list. The material representation should:

1. Be physically-based (or at least physically plausible),
2. Be capable of representing a wide variety of materials,
3. Support sub-surface scattering (including single sheet SSS),
4. Support thin film interference.

From readings and thoughts, I think that requirement no. 2 pretty much implies some sort of layered model to combine simple building blocks into a complex material. This is the route I am following at the moment.

As for references, I have grabbed a copy of Digital Modeling of Material Appearance by Dorsey, Rushmeier and Sillion, which in my opinion gives a good theoretical overview of the topic. And, of course, I am roaming the web for academic papers.

Regarding reference implementations, the PBRT book seems to give the most complete example.