POV-Ray : Newsgroups : povray.general : only 12 objects: rendertime of days Server Time
29 Jul 2024 14:16:21 EDT (-0400)
  only 12 objects: rendertime of days (Message 1 to 7 of 7)  
From: folkert
Subject: only 12 objects: rendertime of days
Date: 1 Aug 2011 11:05:00
Message: <web.4e36c045e8b2d4fb842927590@news.povray.org>
Hi,

I'm trying to render a not so complicated scene: it's only a box with some parts
cut out. In the box a couple (9) of lights.
Now rendering this on a quadcore system in 1280x1024 (-A 0.1) takes days!
This is the result of the script with 1 lightsource (takes 10 hours to render):
http://vanheusden.com/pov/test4c.png
The script with 9 lights can be found here:
http://vanheusden.com/pov/pov-slow.zip

Has anyone any suggestions how i can speed up the rendering? I'm very much
surprised that 1 or 9 lights makes such a difference. But with one light it
still takes almost half a day to render.


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From: Aydan
Subject: Re: only 12 objects: rendertime of days
Date: 1 Aug 2011 11:35:00
Message: <web.4e36c7956532f68a3771cd8e0@news.povray.org>
"folkert" <fol### [at] vanheusdencom> wrote:
> Hi,
>
> I'm trying to render a not so complicated scene: it's only a box with some parts
> cut out. In the box a couple (9) of lights.
> Now rendering this on a quadcore system in 1280x1024 (-A 0.1) takes days!
> This is the result of the script with 1 lightsource (takes 10 hours to render):
> http://vanheusden.com/pov/test4c.png
> The script with 9 lights can be found here:
> http://vanheusden.com/pov/pov-slow.zip
>
> Has anyone any suggestions how i can speed up the rendering? I'm very much
> surprised that 1 or 9 lights makes such a difference. But with one light it
> still takes almost half a day to render.

Well, it looks like it's not "only a box with some parts cut out".
There's at least two reflective planes with what looks like reflection 1.0.
This will greatly increase the number of rays shot.
Also, is the box material reflective? If so you have your answer why it's so
slow.

Regards
Aydan


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From: Thorsten Froehlich
Subject: Re: only 12 objects: rendertime of days
Date: 1 Aug 2011 11:39:34
Message: <4e36c8b6$1@news.povray.org>
On 01.08.11 17:03, folkert wrote:
> Has anyone any suggestions how i can speed up the rendering?

Don't use such a complex CSG object. For every ray traced, the whole 
difference needs to be checked, so you get no benefit of bounding (which you 
cannot add manually in a meaningful way to a difference like this object). 
The best approach here is to split the outer cube into eight symmetrically 
identical smaller cubes. This should get you a speed-up of roughly eight 
times right there.

Also, note that you can texture CSGs as a whole, no need to texture each part.

	Thorsten


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From: Le Forgeron
Subject: Re: only 12 objects: rendertime of days
Date: 1 Aug 2011 11:46:57
Message: <4e36ca71@news.povray.org>
Le 01/08/2011 17:03, folkert nous fit lire :
> I'm trying to render a not so complicated scene: it's only a box with some parts
> cut out. In the box a couple (9) of lights.

Lol, a difference of a Box with about 4000 box for a kind of menger sponge.

You should either:
 1. try an additive approach (union of many smaller boxes)
 2. have some spatial hierarchy in your difference (difference of
sub-union, even difference / union / union) so that the testing of
bounding box does not have to be perform on all objects.

The camera is also on the surface of the cube, which might be an issue
for finding the intersection. (hollow ?)

It might save some characters by declaring the texture and using its
reference


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From: Darren New
Subject: Re: only 12 objects: rendertime of days
Date: 1 Aug 2011 11:53:17
Message: <4e36cbed$1@news.povray.org>
On 8/1/2011 8:03, folkert wrote:
> Has anyone any suggestions how i can speed up the rendering?

Look at the summary at the end of the render and see where POV is spending 
its time.

I have a building with a ton of lights in it, and each light makes it 
slower. I too was getting rendering times of days because the way I had 
constructed the building meant there was no bounding, so every wall was 
being tested against every ray from every light.

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?


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From: folkert
Subject: Re: only 12 objects: rendertime of days
Date: 2 Aug 2011 02:40:01
Message: <web.4e379aaf6532f68a39cbf6460@news.povray.org>
> > Has anyone any suggestions how i can speed up the rendering?
>
> Don't use such a complex CSG object. For every ray traced, the whole
> difference needs to be checked, so you get no benefit of bounding (which you
> cannot add manually in a meaningful way to a difference like this object).
> The best approach here is to split the outer cube into eight symmetrically
> identical smaller cubes. This should get you a speed-up of roughly eight
> times right there.
>
> Also, note that you can texture CSGs as a whole, no need to texture each part.

As a quick test I replaced the CSG by a combination of individual boxes.
My quadcore took days for the CSG, in the new version my intel atom laptop takes
seconds :-)
Thanks you all for the suggestions!


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From: Thomas de Groot
Subject: Re: only 12 objects: rendertime of days
Date: 2 Aug 2011 04:11:34
Message: <4e37b136$1@news.povray.org>
Look at this site: http://www.econym.demon.co.uk/holetut/index.htm it 
will answer some of your problems.

Thomas


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