POV-Ray : Newsgroups : povray.newusers : Metal textures : Re: Metal textures Server Time
21 Jun 2024 11:04:35 EDT (-0400)
  Re: Metal textures  
From: clipka
Date: 12 Dec 2015 08:00:38
Message: <566c1a76@news.povray.org>
Am 12.12.2015 um 07:32 schrieb Sherry K. Shaw:
> Here's a question--
> I haven't yet taken the time* to experiment much with the new features
> of 3.7 in regard to specifically metallic textures,** but now I'm
> curious--has "brilliance" been affected by the changes to the finish
> statement, and, if so, how?  Because it strikes me that brilliance has
> been an important component of metallic textures for quite a while,
> possibly twenty years or so--oh, good God, have I been Povving THAT
> long?  Oh, dear lord, I'm old!  OLD!

"Brilliance" has been affected insofar as it now interacts with the
effective diffuse brightness /if/ you use the new "diffuse albedo FLOAT"

Using the traditional "diffuse FLOAT" syntax, the parameter value
directly specifies the /maximum/ brightness of the diffuse reflection,
i.e. the apparent brightness of the surface when looking at it exactly
perpendicular; the "brilliance" keyword only affects the apparent
brightness when looking at the surface from a more shallow angle.

Using the new "diffuse albedo FLOAT" syntax, the parameter value
specifies the /total/ brightness of the diffuse reflection, integrated
over the entire hemisphere. At the default brilliance of 1.0, this has
the same effect as the old "diffuse FLOAT"; however, as brilliance
increases and the diffuse reflection "tightens", this now increases its
/maximum/ brightness.

That said, the use of "diffuse" (and, by extension, "brilliance") in
metallic textures has no physical justification, and is only there
because back then the primary approach to designing textures was to
tweak them until the author thought it looked as realistic as he could
possibly manage, rather than starting from principles of physics.

As for using "brilliance" in metallic textures, it makes the diffuse
component appear more highlight-ish, and highlights are what our brain
expects from metallic surfaces.

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