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POV Manual Quote...
6.11.11.2.13 Pretrace
To control the radiosity pre-trace gathering step, use the keywords
pretrace_start and pretrace_end within the radiosity{} block. Each of
these is followed by a decimal value between 0.0 and 1.0 which specifies
the size of the blocks in the mosaic preview as a percentage of the
image size. The defaults are 0.08 for pretrace_start and 0.04 for
pretrace_end
Yes, but does the pretrace affect the quality of radiosity or is it just
a mosaic effect for the render-window?
It's not quite clear from the above if smaller values will give better
results.
I know for sure it will generate smaller squares in the mosaic!
object {
Grey_Matter
photons { target Need_More_Info }
}
Thanks
--
(MIKA) Marc Champagne
marcch.AT.videotron.DOT.ca
Montreal, CANADA
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"Marc Champagne" <nos### [at] please com> wrote in message
news:Xns### [at] 204 213 191 226...
>
> 6.11.11.2.13 Pretrace
> To control the radiosity pre-trace gathering step, use the keywords
> pretrace_start and pretrace_end within the radiosity{} block.
>
>
> Yes, but does the pretrace affect the quality of radiosity or is it just
> a mosaic effect for the render-window?
It is doing a sampling of areas, so yes, it is a quality factor. Pretrace
isn't the same as mosaic preview, only looks it.
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From: Xplo Eristotle
Subject: Re: MIKA radiosity & pretrace question
Date: 5 Oct 2002 06:50:57
Message: <3d9ec411@news.povray.org>
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Marc Champagne wrote:
>
> ...does the pretrace affect the quality of radiosity or is it just
> a mosaic effect for the render-window?
>
> It's not quite clear from the above if smaller values will give better
> results.
In some cases, smaller pretrace_end values will help smooth artifacts
(slightly); in other cases, a smaller value has no appreciable effect.
Obviously, in all cases, a lower value will increase rendering time.
-Xplo
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From: Christoph Hormann
Subject: Re: MIKA radiosity & pretrace question
Date: 7 Oct 2002 12:27:27
Message: <3DA1B5ED.3B9BD55C@gmx.de>
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Marc Champagne wrote:
>
> [...]
>
> Yes, but does the pretrace affect the quality of radiosity or is it just
> a mosaic effect for the render-window?
>
> It's not quite clear from the above if smaller values will give better
> results.
>
In general you can say: lower pretrace_end -> higher quality and slower
render. But how much you gain depends on the other settings. As a rule
of thumb you can say a low error_bound also profits from low
pretrace_end. A high error_bound combined with a low pretrace_end is just
a waste of time.
Christoph
--
POV-Ray tutorials, IsoWood include,
TransSkin and more: http://www.tu-bs.de/~y0013390/
Last updated 13 Aug. 2002 _____./\/^>_*_<^\/\.______
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