POV-Ray : Newsgroups : povray.general : Tracking down slow renders : Re: Tracking down slow renders Server Time
25 Jul 2024 10:01:11 EDT (-0400)
  Re: Tracking down slow renders  
From: Kenneth
Date: 6 May 2023 07:45:00
Message: <web.64563cb95485baa99b4924336e066e29@news.povray.org>
"Chris R" <car### [at] comcastnet> wrote:
> What I'm afraid of is that some interaction
> between anti-aliasing, radiosity, and reflection is causing an infinite loop
> measuring against thresholds.

That's a really hard-core set of features to throw at POV-ray all at once, ha.
Especially with isosurfaces added to the mix. I have similar scenes where I had
to eliminate anti-aliasing altogether, if I didn't want to exclusively tie up my
machine for days...and this on an 8 core/16 thread machine!

My gut-feeling is that the slowdown for your last block is AA-related.

One suggestion would be to reduce the size of your Render_Blocks. The default is
32X32 pixels, I think. I run complex-feature scenes at 8X8, which does improve
the overall rendering speed on multi-core machines, and *helps* to keep that
final render block from taking so much time. As Thorsten F. pointed out in an
earlier post last year, each Render_Block uses an individual core (or thread-- I
get the two confused.) By reducing the block size, the processor seems to work
more efficiently, and doesn't have to spend all of its time on a single block
(with a single core) while the other cores are sitting idle. Or something like

I may have the technicalities wrong, but a smaller block size can sometimes
speed-up the render. It definitely works for media and isosurfaces (but I'm not
patient enough to throw in AA as well; most of my renders lately are just
relatively quick tests of one thing or another.)

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