Am 31.03.2016 um 19:27 schrieb clipka:
> I've just released an experimental version of POV-Ray implementing two
> alternative models for diffuse reflection, besides the classic so-called
> Lambertian model:
> 
> https://github.com/POV-Ray/povray/releases/tag/v3.7.1-alpha.8545805%2Bav122

A new build is currently in the making:

- The bug in the Oren-Nayar implementation has been fixed.

- I got the interaction between Oren-Nayar and Lommel-Seeliger the wrong
way round; this has also been fixed, so that it now works as described
previously in this thread.

- The difference in effective brightness (bihemispherical albedo for the
technically inclined) between the models can now be compensated for by
using the `diffuse albedo FLOAT` syntax (which had already been doing
the same job with respect to the `brilliance` mechanism). The `diffuse
FLOAT` syntax still gives a canonical brightness parameterization of the
models. (*)

- Interaction with radiosity has been improved. As the radiosity
algorithm cannot make use of the new models, and therefore always falls
back to the Lambertian model, it also suffered from the difference in
effective brightness between the models, with materials using Oren-Nayar
or Lommel-Seeliger appearing brighter under radiosity illumination than
under classic illumination. This has also been fixed along the way.


(* It might be worth noting that the `diffuse albedo FLOAT` syntax does
/not/ change the Lommel-Seeliger parameter's original meaning: Using
`lommel_seeliger K` /always/ computes a K:(1-K) weighted average of
_canonical_ Lommel-Seeliger and Lambert; only /then/ is any correction
factor applied to achieve a specified bihemispherical albedo.)

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