"Nathan Kopp" <Nat### [at] Koppcom> wrote in message
news:38d7dc0b$1@news.povray.org...
>
> I think that it's a somewhat illusionary effect but
> is most likely related to gamma correction.

I think you're right.  I made a larger image and the effect was almost
unnoticable... playing with my monitor's controls helped, too.

> Some people have complained about similar
> 'problems' with scattering media.  It is caused
> by diffuse light bouncing off of the glass being
> added to the transmitted light that comes
> through the glass.
>
> Also, if the description of your material does not
> conserve energy (if reflected light, including diffuse,
> phong, etc, plus transmitted light adds up to more
> than 1.0) then you could run into problems like this.

The complete texture was:

  $ GlassMat = material {
    texture {
      pigment {rgbf <0.9,0.9,0.9,0.9>}
      finish {reflection 0}
    }
  }

reflection 0 was added after I noticed the effect to see if the visible
floor plane in the "glass" was in front of or behind the glass.  It didn't
make a difference in the image.

Eric
--------------------
http://www.datasync.com/~ericfree
--------------------
"I don't like it, and I'm sorry I ever had anything to do with it."
- Erwin Schrodinger talking about Quantum Mechanics.

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