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From: Tim Nikias
Subject: Too many nested objects
Date: 18 Sep 2004 14:22:45
Message: <414c7cf5$1@news.povray.org>
I just got this error. I'm not complaining about it as it surely has a
reason to be there, still, a few questions:

-How many objects may I nest and in which circumstances do they count?
Knowing something more specific would help in testing for a workaround.

-Does max_trace_level also affect the depth of rays through nested objects?
If so, wouldn't it be possible to somehow raise the limit for nested objects
to a value that would work with max_trace_level 256 (POV's trace-cap, which
is sufficient IMHO)?

My line of thought is simply that, if I specify a max_trace_level, I'd
rather expect black spots instead of chickening out on a render. ;-)

Regards,
Tim

-- 
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>


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From: Slime
Subject: Re: Too many nested objects
Date: 18 Sep 2004 15:30:42
Message: <414c8ce2$1@news.povray.org>
> -How many objects may I nest and in which circumstances do they count?
> Knowing something more specific would help in testing for a workaround.

I think the "Too many nested objects" error occurs when a ray passes through
a large number of surfaces of different objects without ever passing *out*
of any of the objects.

Sometimes, however, this is avoidable. For instance, this error can
(theoretically) occur when you're using the "stacked planes" method for
clouds; if you use n planes for n layers of cloud detail, and n is too
large, then you'll get the error because all of the upper planes are inside
of the lower planes.

However, if you switch to n/2 intersections of 2 planes each, so that
there's an upper and a lower plane for each pair and the "inside" of the
object is the space between them, rays going through them will go into an
object, then out of that object, in and out, until they reach the other
side, and the error is avoided.

This workaround can be used for basically any situation except those where
the interiors of the objects are important.

 - Slime
 [ http://www.slimeland.com/ ]


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From: Tim Nikias
Subject: Re: Too many nested objects
Date: 18 Sep 2004 19:50:55
Message: <414cc9df@news.povray.org>
> This workaround can be used for basically any situation except those where
> the interiors of the objects are important.

I'm working with a particle system which uses textured, hollow half-spheres
(that are halved using clipped_by), in addition with a few complete spheres
filled with media, so the workaround cannot be applied. I'm also not quiet
sure how many particles there are. In effect, if I'd close the rear end of
the half-spheres, so that POV-Ray knows when it exits a particle, it might
work better? Or does POV-Ray know it, and I'm simply using too many
particles/spheres?

Do you, by any chance, know exactly how deep into objects POV-Ray can trace
without reaching the nested-max?

Regards,
Tim

-- 
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>


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From: Slime
Subject: Re: Too many nested objects
Date: 19 Sep 2004 00:21:51
Message: <414d095f$1@news.povray.org>
> In effect, if I'd close the rear end of
> the half-spheres, so that POV-Ray knows when it exits a particle, it might
> work better?

Yeah, that should do it. Instead of clipping them, use a difference with a
plane that has a transparent texture.

> Do you, by any chance, know exactly how deep into objects POV-Ray can
trace
> without reaching the nested-max?

No, but it shouldn't be too difficult to figure out through guess-and-check.
Or it may be in the documentation somewhere.

 - Slime
 [ http://www.slimeland.com/ ]


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From: Thorsten Froehlich
Subject: Re: Too many nested objects
Date: 19 Sep 2004 02:42:35
Message: <414d2a5b$1@news.povray.org>
In article <414cc9df@news.povray.org> , "Tim Nikias" 
<JUSTTHELOWERCASE:timISNOTnikias(at)gmx.netWARE> wrote:

> Do you, by any chance, know exactly how deep into objects POV-Ray can trace
> without reaching the nested-max?

100.  If you hit that limit, change your scene because if you hit it, you
can be certain there is something very inefficient in your scene.

    Thorsten


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From: Tim Nikias
Subject: Re: Too many nested objects
Date: 19 Sep 2004 05:47:06
Message: <414d559a@news.povray.org>
> > Do you, by any chance, know exactly how deep into objects POV-Ray can
trace
> > without reaching the nested-max?
>
> 100.  If you hit that limit, change your scene because if you hit it, you
> can be certain there is something very inefficient in your scene.

Yeah, I'd expect that to be inefficient for standard scenes. But when I use
a particle system with hundreds of particles, such things can easily happen.
But I guess it's not that easy to raise that limit without requiring much
more memory.
Thanks for responses, Slime and Thorsten!

Regards,
Tim

-- 
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>


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From: Warp
Subject: Re: Too many nested objects
Date: 19 Sep 2004 07:42:40
Message: <414d70b0@news.povray.org>
Tim Nikias <JUSTTHELOWERCASE:timISNOTnikias(at)gmx.netWARE> wrote:
> Yeah, I'd expect that to be inefficient for standard scenes. But when I use
> a particle system with hundreds of particles, such things can easily happen.

  You might want to rework your particle system so that if there is more
than 100 particles one inside another, not all of them are actually
instantiated (it wouldn't make any difference in the image anyways).

-- 
plane{-x+y,-1pigment{bozo color_map{[0rgb x][1rgb x+y]}turbulence 1}}
sphere{0,2pigment{rgbt 1}interior{media{emission 1density{spherical
density_map{[0rgb 0][.5rgb<1,.5>][1rgb 1]}turbulence.9}}}scale
<1,1,3>hollow}text{ttf"timrom""Warp".1,0translate<-1,-.1,2>}//  - Warp -


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From: Tim Nikias
Subject: Re: Too many nested objects
Date: 19 Sep 2004 08:04:14
Message: <414d75be$1@news.povray.org>
>   You might want to rework your particle system so that if there is more
> than 100 particles one inside another, not all of them are actually
> instantiated (it wouldn't make any difference in the image anyways).

Not really possible. Particles can be animated using Macros, additionally,
several particle systems might run at a given time. Tracking all their sizes
and positions doesn't seem feasible. And the workaround should be tailored
to the actual scene, instead of just removing particles on a general basis.
In my case, I just used fewer particles and made them less transparent,
works fine for this scene.

That aside, how do discs add up to the nesting? They've only got one
surface.

-- 
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>


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From: Warp
Subject: Re: Too many nested objects
Date: 19 Sep 2004 08:14:44
Message: <414d7834@news.povray.org>
Tim Nikias <JUSTTHELOWERCASE:timISNOTnikias(at)gmx.netWARE> wrote:
> That aside, how do discs add up to the nesting? They've only got one
> surface.

  Most primitives have only one surface, yet that doesn't stop them from
having an inside, even when this surface is open.
  Just test discs in CSG with other objects to see their inside.

-- 
plane{-x+y,-1pigment{bozo color_map{[0rgb x][1rgb x+y]}turbulence 1}}
sphere{0,2pigment{rgbt 1}interior{media{emission 1density{spherical
density_map{[0rgb 0][.5rgb<1,.5>][1rgb 1]}turbulence.9}}}scale
<1,1,3>hollow}text{ttf"timrom""Warp".1,0translate<-1,-.1,2>}//  - Warp -


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From: Tim Nikias
Subject: Re: Too many nested objects
Date: 19 Sep 2004 08:29:40
Message: <414d7bb4$1@news.povray.org>
>   Most primitives have only one surface, yet that doesn't stop them from
> having an inside, even when this surface is open.

Yeah, I knew that. Discs are just planes with a limited visibily radius
(idiot speaking here, but that's kinda the code behind a disc, right?).
Which object wouldn't have an inside, so that nesting doesn't occur? Do
triangles have insides? Something that could replace the disc in the
particle system but doesn't add to nesting?

-- 
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>


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