I have been playing around with renderings of painted surfaces that
realistically model the standard paint gloss values and also show brush strokes
or roller patterns.  Along the way I read some detailed descriptions of how
finish level fresnel works and now I'm curious.

Reading the wiki and some documentation I received via the newsgroups earlier,
it seems that for best realism, if using finish-level fresnel, you just always
set:

specular albedo 1.0
diffuse albedo 1.0

and then adjust the roughness to the glossiness you want in the surface.  That
is, in fact, what I did with my paint finishes and they look pretty good, at
least for high-gloss, semi-gloss, and satin.  (I don't see much differentiation
in my eggshell and matte settings yet.)

So, are there particular effects or materials where you would get realistic
results with specular and diffuse values not 1.0 with fresnel, or can those
effects be better handled with surface normals, pigment adjustments, and the
interior ior value of the object?

Looking back on many of my past projects since I started using fresnel finishes,
I notice that I am not following the rules and am probably fighting the system.

-- Chris R.

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