Well absorption works exactly the same as black fog. I worked the maths out for
fog once:

For example, if visibility at 1 metre is 90%, then at 2 metres it will be 90% of
90%, i.e. 81%. Basically  visibility = pow( visibility at distance of 1,
distance )

Absorption is kind of the other way round, so if you have 10% absorption you
have 90% visibility (though don't ask me how pov's density and stuf comes into
it). So, negative absorption actually increases visibility!

--
Tek
http://www.evilsuperbrain.com

"Slime" <slm### [at] slimelandcom> wrote in message news:3eb1a665$1@news.povray.org...
> > Surely it's more of a multiplying force? so things viewed through negative
> > absorption will have their colour increased by it, multiplicitavely. i.e.
> black
> > things will stay black which they won't with emission.
>
>
> Is that how it works? I know that emission is additive, but i never figured
> out how absorption works. I imagine it involves some sort of complicated
> integral, since it seems to be sort of like an infinite number of
> nearly-transparent thin layers.
>
> I always wonder about the math behind these things.
>
>  - Slime
> [ http://www.slimeland.com/ ]
>
>

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