Simen Kvaal wrote:
> 
> >The pigment of the surface is added to the reflected colour. So rgb
> ><1,0,0> reflection 1 is not a pure red mirror. A pure red mirror would
> >be rgb <0,0,0> reflection <1,0,0>
> 
> I thought it was the fact that the surface absorbs all other frequencies
> than red, and all red incoming light is reflected. I believe that it is the
> color model that makes the topic a bit fuzzy. If one could model the light
> as a collection of frequencies rather than only <r, g, b>, we could get
> simpler modelling. But I am not sure.

The person doing the light model would have to have considerable knowlege
of light and light frequencies and I doubt the "average" Pov user would
want to go to the trouble of learning it for simple color operations.
 
> As for the secont question: Yes, light is reflected more perfectly at acute
> incoming angles. I believe it is very difficult to model accurately. You
> would have to supply several parameters, like the reflection rate when the
> incoming ray is perpendicular to the surface normal (this would never
> happen, though...), the rate of reflection when the incoming ray is
> parallell to the surface normal, and so forth. That is, if it is not a clear
> relation between the values that are "universal." I have thinked of it,
> myself, but I haven't come across any papers on the phenomena. Anyone?

You will find more information on incident angles of reflection in
photography texts. It has been well researched and documented. You
might try a search of online siggraph papers at:

http://w3imagis.imag.fr/Membres/Fredo.Durand/Book/sig98.html


-- 
Ken Tyler
1100+ Povray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html

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