Hello all, I was wondering is there were any good modern resources, in the form of online PDF documents, videos, powerpoints etc. or books that I could use to learn about physically based BDRF models in relation to techniques such as:
- Cook-Torrance microfacet BDRF for specular surfaces
- Lazarof's visibility model
- Anisotropic specular
- Lambertian diffuse
- Shirley's Fresnel term
- Penner and Borshukov's sub-surface scattering model for skin
Cook-Torrance: http://www.codinglabs.net/article_physically_based_rendering_cook_torrance.aspx
Large set of references: http://graphicrants.blogspot.com/2013/08/specular-brdf-reference.html
More: http://simonstechblog.blogspot.com/2011/12/microfacet-brdf.html
You'll almost certainly want to use Smith's geometry shadowing term for the best look for performance.
Schlick is a very... Slick 
approximation of frensel and is generally what's used: https://en.wikipedia.org/wiki/Schlick%27s_approximation
How you do subsurface scattering matters more for realtime performance than exact formulation/matching measured data. Activision and ye CoD guys did a really nice and cheap approximation for Advance Warfare et. al. http://www.iryoku.com/next-generation-post-processing-in-call-of-duty-advanced-warfare
After you mastered all these BRDFs, you can try to combine them following the techniques described in this paper
"GenBRDF: Discovering New Analytic BRDFs with Genetic Programming"
Added to my list of resources Thanks! Now I have like 9 word document pages full of resources so far and ever expanding!
Once you get a basic understanding I highly recommend getting Disney's BRDF Explorer: http://www.disneyanimation.com/technology/brdf.html
It was a big help for me to understand how different compenents of a BRDF work together using instant visual feedback and playing with the formulas which come with the software. Once you get your head around it you can then program your own formulas or use combinations of existing ones.
It's a great tool and it's free!
