Am 27.07.2018 um 18:02 schrieb Iodine:
> I would like to ask if anyone has ever considered how to make a texture for a
> droplet of dirty water.
> 
> If we consider for a moment a glass or a water, then it will have a refractive
> index, also the medium will have an ability to adsorb light. The adsorption of
> light can be expressed with ease in real life using the equation
> 
> Log (I / I0) = A = El
> 
> Where I is the intensity of light leaving the object on a given path, Io was the
> light which would be leaving the object on that path if no adsroption was to
> occur. While E is a constant while l is the length of the path through the
> object.

That's how POV-Ray's "media" feature works, and if the average number of
scattering/absorption events per photon is significantly smaller than 1
(i.e. cases where you can still see through the fluid) it gives pretty
good results.

If the medium is supposed to be uniform and absorption is dominant,
there's also a faster mechanismus, referred to as distance-based
attenuation; search for keywords `fade_distance` and `fade_power` (in
the context of interior; the same keywords also occur in the context of
light sources, but that's something different).


For materials where the expected number of scattering/absorption events
per photon is significantly higher than 1 (i.e. cases where you cannot
see through the fluid), the subsurface light transport feature probably
gives the most realistic results.

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