Jeremy M. Praay wrote:
> Thanks.  That's along the lines of what I was thinking.  As a real-world 
> example, where I work, I sit under some strange yellow flourescent lights. 
> Some of the papers strewn around my desk look white, others look very yellow 
> or grey.  If I pick up those same papers and take them into my boss's office 
> (different type of flourescent lights), they all look white.

   That is metamerism, IIRC... and that's not possible without the 
raytracer handling wavelengths internally (that is, Lightsys can't 
simulate it).

> Like I said to Jaime, I would guess that the reflectance values in POV-Ray 
> probably are less significant than some of the other things we guess at in 
> the finish statement (or at least I guess at them), like specular, phong, 
> reflection, diffuse, brilliance, etc.  I think it would be nice if POV-Ray 
> had more materials predefined using more physically accurate data.  Lightsys 
> is a great step in that direction.  Does anyone know where to get 
> information on those finish values?

   The only pointer I got is reflection+diffuse=1. I really don't know 
where it comes from, but I've seen it mentioned several times by people 
which seems to know what they are talking about... and indeed seems 
logical and gives good results. For the rest, we still have to use the 
good and old "trial & error", I suppose.

--
Jaime

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