POV-Ray : Newsgroups : povray.documentation.inbuilt : Finish-level Fresnel : Re: Finish-level Fresnel Server Time
28 Sep 2022 13:07:39 EDT (-0400)
  Re: Finish-level Fresnel  
From: clipka
Date: 21 Dec 2016 11:39:14
Message: <585ab032$1@news.povray.org>
Am 21.12.2016 um 16:35 schrieb clipka:

> So we might just as well replace the entire section with something like:
> -------------------------------------------------------
> exponent
> This property pre-dates the introduction of proper gamma handling.
> People found that it was difficult to model partially reflective
> surfaces in a realistic way, as middle and lower brightness objects
> typically looked too bright when reflected. As a means work around the
> phenomenon the optional exponent keyword was added, producing non-linear
> reflection intensities. The default value of 1.0 produces a linear
> curve. Lower values darken middle and low intensities and keep high
> intensity reflections bright. While this feature may still be used for
> artistic effects, it is strongly discouraged for renders aiming at
> realism. The original phenomenon is well understood by now, and using
> "assumed_gamma 1.0" as recommended will avoid it entirely.
> -------------------------------------------------------
> 
> (Hold off on this for a moment though; I'll do a few experiments to
> verify that I'm right in my explanation of that old phenomenon.)

Go ahead. My hypothesis turns out to fit nicely.


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