Juraj, what do you mean by "depending on philosophy", where do you find this stuff? I am very interested to read about that if you don't mind can you provide a link or book name.
From varied sources like BRDF fittings of the measured MERL data to guides toward PBR/Photorealistic visuals in games like the famous DONTNOD guide and writings from Sebastien Lagarde/ John Habble/ Paul Devebec/ Pixar stuff/etc.
I could give you about 50+ links but the best is to start from this collection :- ) Other artists have already created a very comprehensive reading:
PBR Encyclopedia:
https://docs.google.com/document/d/1Fb9_KgCo0noxROKN4iT8ntTbx913e-t4Wc2nMRWPzNk/editRegarding the "philosophy", my issue is, some of these guides, are sometimes contraindicative. For example the Seb. Lagarde, a big authority, advices to keep Albedo brighter then we think,
then from albedo charts we know that even brightest material aren't so bright, but interpolating between these data to author your own materials can sometimes be painful. The only easy thing remain metals.
I wish there was some definite, approved way how to author material values. There are tutorials about the use of Macbeth chart, but these always end up as reference only. There's no exact way how to convert the photography
derived values to values I can fit to material so I would get identical result. And there is no way how to compare results either, it annoys me I can either look at mathematical linear space, which tells me nothing, or ugly, bleak reinhard (yes Corona has the same as Vray, just oppositely mapped controls) that looks nothing like any contemporary camera sensor. Realism stills requires too much effort and tricks and there is little on how to keep it consistent. Everytime we admire some photorealistic result, it's more matter of happy coincidence that deliberate effort. Perhaps simple scene with good angle, good diffuse light, and lot of reflective materials. A more of a luck.
Everytime I go create wooden floor, I don't know how bright and saturated my albedo/diffuse texture should be. And I can't trust a reference photography I have even if I recreated identical time of the day, scene and camera exposure. Because the photography already has certain dynamic range and response curve and my render doesn't and there is no tonemapping that would give me result resembling my photography directly. So instead, I am juggling everything. Tweak this here, now tweak that there. By eye, eye-ball it. It takes too much times, it's frustrating, and it's completely unnecessary. I am literally annoyed there isn't enough research done to create 'out-of-the-box' realism.
I hope that until I am 30, there will be at least : Photorealistic tonemapping resembling modern day cameras. Not Reinhard + Contrast for god sakes. Material system that will forever say goodbye to specular/glossiness and incorporate easy feeding of values that can be derived from existing tools.
Sorry for rambling, you asked :- ) Now I can get back to work.
