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Hello,
Does POVRay 3.5 use some kind of importance sampling or weighted
importance sampling when taking random samples to solve the diffuse
interreflection integral? I've been looking at the MegaPOV source but its
not yet clear to me if this is the case or if it applies here.
Thanks again,
George Pantazopoulos
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From: Christoph Hormann
Subject: Re: 3.5 Radiosity - importance sampling?
Date: 21 Apr 2002 13:03:43
Message: <3CC2F0EF.6DDAF486@gmx.de>
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George Pantazopoulos wrote:
>
> Hello,
> Does POVRay 3.5 use some kind of importance sampling or weighted
> importance sampling when taking random samples to solve the diffuse
> interreflection integral? I've been looking at the MegaPOV source but its
> not yet clear to me if this is the case or if it applies here.
If you explain what 'importance sampling' is i'm quite sure i can answer
your question.
Christoph
--
POV-Ray tutorials, IsoWood include,
TransSkin and more: http://www.tu-bs.de/~y0013390/
Last updated 20 Apr. 2002 _____./\/^>_*_<^\/\.______
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From: George Pantazopoulos
Subject: Re: 3.5 Radiosity - importance sampling?
Date: 21 Apr 2002 13:09:48
Message: <3cc2f25c$1@news.povray.org>
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Sorry Christoph, I guess I've been reading too many global illumination
papers, and they've been numbing my brain :) From my understanding so far,
importance sampling attempts to reduce the rays needed, and/or put the ones
cast to better use by not simply shooting rays/particles in a random manner,
but by attempting to adaptively "target" them to the areas that will make
the most difference.
Thanks,
George Pantazopoulos
"Christoph Hormann" <chr### [at] gmx de> wrote in message
news:3CC2F0EF.6DDAF486@gmx.de...
>
>
> George Pantazopoulos wrote:
> >
> > Hello,
> > Does POVRay 3.5 use some kind of importance sampling or weighted
> > importance sampling when taking random samples to solve the diffuse
> > interreflection integral? I've been looking at the MegaPOV source but
its
> > not yet clear to me if this is the case or if it applies here.
>
> If you explain what 'importance sampling' is i'm quite sure i can answer
> your question.
>
> Christoph
>
> --
> POV-Ray tutorials, IsoWood include,
> TransSkin and more: http://www.tu-bs.de/~y0013390/
> Last updated 20 Apr. 2002 _____./\/^>_*_<^\/\.______
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From: Christoph Hormann
Subject: Re: 3.5 Radiosity - importance sampling?
Date: 21 Apr 2002 14:35:56
Message: <3CC3068B.4A6DD376@gmx.de>
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George Pantazopoulos wrote:
>
> Sorry Christoph, I guess I've been reading too many global illumination
> papers, and they've been numbing my brain :) From my understanding so far,
> importance sampling attempts to reduce the rays needed, and/or put the ones
> cast to better use by not simply shooting rays/particles in a random manner,
> but by attempting to adaptively "target" them to the areas that will make
> the most difference.
Ah, i think i understand.
AFAIK POV-Ray does not do this currently, but i'm not sure how you would
accomplish that anyway (how to know in which directions sampling is
needed)
Christoph
--
POV-Ray tutorials, IsoWood include,
TransSkin and more: http://www.tu-bs.de/~y0013390/
Last updated 20 Apr. 2002 _____./\/^>_*_<^\/\.______
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From: George Pantazopoulos
Subject: Re: 3.5 Radiosity - importance sampling?
Date: 21 Apr 2002 14:46:06
Message: <3cc308ee$1@news.povray.org>
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Perhaps you could very cheaply (scanline/zbuffer/hardware?) render a
low-resolution "view" from the primary intersection point, and then use the
brightness/contrast information to affect the distribution of the rays cast
from that point?
> > Sorry Christoph, I guess I've been reading too many global illumination
> > papers, and they've been numbing my brain :) From my understanding so
far,
> > importance sampling attempts to reduce the rays needed, and/or put the
ones
> > cast to better use by not simply shooting rays/particles in a random
manner,
> > but by attempting to adaptively "target" them to the areas that will
make
> > the most difference.
>
> Ah, i think i understand.
>
> AFAIK POV-Ray does not do this currently, but i'm not sure how you would
> accomplish that anyway (how to know in which directions sampling is
> needed)
>
> Christoph
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