Am 17.07.2012 18:09, schrieb Chaanakya:

> 4) I have found that if I only specify the IOR, conserve_energy, and fresnel
> (with no pigment { transmit N.N } block), the object looks black.  This is the
> one thing I don't understand.

Specify "transmit 1.0"; with conserve_energy, AFAIK you should be fine.

POV-Ray doesn't automatically do that for you because some people 
/might/ want to model non-transparent reflective materials, you know ;-)

You might argue that specifying an ior should automatically imply 
transparency, but this is not so: Real life opaque surfaces (or rather, 
surfaces of opaque materials) obey fresnel's law as well, so for best 
realism you need to use "fresnel on" and specify an ior for those as 
well, and even top it off with "conserve_energy" to modulate the diffuse 
reflection accordingly.

(All non-metallic "opaque" materials are actually transparent with very 
strong absorption and/or scattering effects; it would be too complex to 
model them as such though, hence the shortcut with a "surface color".)

If you have a scene with plenty of transparent stuff, you might want to 
specify "default { pigment { rgbt 1 } }" at the beginning of your scene 
file to save you a bit of typing.

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