POV-Ray : Newsgroups : povray.binaries.images : Impending Disaster : Re: Impending Disaster Server Time
6 Jul 2022 00:28:23 EDT (-0400)
  Re: Impending Disaster  
From: Kenneth
Date: 29 Jan 2022 03:20:00
Message: <web.61f4f796941abfdd4cef624e6e066e29@news.povray.org>
Looking through the "rad_def" include file, I see that all of the radiosity
entries there are missing a  maximum_reuse  value-- which means that it defaults
to 0.2 in all of the cases. That's a rather large value, and can produce some
large-sized splotches. (From the docs' explanations of the various rad settings,
and possibly from code examples I've seen there(?), the 'typical' spread between
minimun_reuse and maximum_reuse should(?) be approximately 1:13; I guess that's
a trade-off between quality and render speed. And the spread is also designed so
that large flat surfaces get the maximum value-- large smooth rad patches--
whereas curved surfaces or other 'non-flat' areas get smaller patches.

Personally, I now like to use a *small* spread between min and max_reuse; it
kind of defeats the purpose of the render-speed trade-off, and produces patches
that are all of the same (smaller) size; but I like the higher-quality look,
especially if rad's count value is greatly increased to produce more patches.

Anyway...

As an experiment when using, say, the "rad_def" Radiosity_Fast entry (which has
a minimum_reuse value of 0.025), add a maximum_reuse there of 0.026. And greatly
increase the 'count' value. It will be a slow render, so maybe pick out a
smaller section of the image to test (and turn off AA). I can't predict what the
results will be, but this *might* improve the results.

BTW: In your image post, it looks like some of the objects' colors might be
exceeding <1.0,1.0,1.0>, perhaps due to the combination of lights used. This
could be a reason for some of the rad artifacts. Try decreasing the objects'
diffuse values a bit, so that nothing in the scene produces a max color
brightness exceeding 1.0. It will probably be a guessing game of trial and error
;-)


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