POV-Ray : Newsgroups : povray.newusers : Should Parsing really take that long? How to speed it up? Server Time
31 Oct 2024 20:12:56 EDT (-0400)
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From: ILM
Subject: Re: Should Parsing really take that long? How to speed it up?
Date: 6 Dec 2015 08:55:01
Message: <web.56643de1fb84f5bafcb4e70@news.povray.org>
> I'll do a few tests to see whether I'm overlooking something about the
> mechanism behind image_map duplication, but at the moment the hypothesis
> that makes most sense to me is that you made some trivial mistake when
> testing with the 30,000 "#declare cube=..." lines removed, such as using
> an external editor to make the change and forgetting to save before
> rendering.


I checked this again to be sure. This unfortunately seems true :(. I again
removed those lines and now parsing took only 15 seconds.


> This morning I looked at the PNG I grabbed for my 30K declare experiment
> and it turned out to be only 160x120 pixels... I scaled this PNG up to
> 1600x1600 and re-ran and the parse time jumped to 14 minutes even using
> a memory disk. So, the thousands of duplicate declares absolutely can
> drive large parse times if the PNG files are larger as you and Christoph
> have suggested.
>
> Let's see... 160x120 & 30K declares at 25sec we get 0.013 sec/pixel.
> 1600x1600 & 30K declares at 820sec we get 0.0003sec/pixel so nothing
> wrong in the direction that is scaling with larger PNGs either.

Thats something I realized too. I tried to re-save the png files with better
compression. This saved about 30-50% file size, but had more or less no effect
to the parsing time.

So the pixel-size of the pngs seems to be a critial factor to parsing time.

But as stated above it seems like something went wrong with removing the declare
line in the first time. I am sorry for that.

I will contact the developers of the software tomorrow. Maybe they have a quick
fix for that. Thank you all for your help! I will keep you updated.


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