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> ... the distribution is stronly anisotropic at the lower
> parts of the hemisphere.
Should the distribution isotropic then? I did my best generating a costheta
distribution, which is an anisotropic distribution. But maybe I'm completely
wrong and confused here heheheheh....... (All I want is a HUGE set of
samples that have the same quality the distribution set of the currently
official POV-Ray.)
If I would like to distribute the samples randomly but still evenly on a
(hemi)sphere, off course I wouldn't use any 2d projections onto spheres.
Using 3d math will be much more convenient in such a case IMHO.
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Agreed, but with POV-Ray doesn't use all the samples every time:
error_bound, count and minimum_reuse will limit the samples taken.
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From: Christoph Hormann
Subject: Re: 32000 radio samples (there we go again)
Date: 10 Apr 2003 13:57:30
Message: <3E95B08A.4A0A78B3@gmx.de>
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Apache wrote:
>
> > ... the distribution is stronly anisotropic at the lower
> > parts of the hemisphere.
> Should the distribution isotropic then? I did my best generating a costheta
> distribution, which is an anisotropic distribution.
No. I have explained this before, the varying density does not
necessarily mean anisotropy. Anisotropic means the density depends on the
direction on the sphere surface (in your distribution the samples are more
dense in circumference direction than in theta direction).
Christoph
--
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 28 Feb. 2003 _____./\/^>_*_<^\/\.______
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From: Christoph Hormann
Subject: Re: 32000 radio samples (there we go again)
Date: 10 Apr 2003 14:02:32
Message: <3E95B1B7.3B5424B3@gmx.de>
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Apache wrote:
>
> Agreed, but with POV-Ray doesn't use all the samples every time:
> error_bound, count and minimum_reuse will limit the samples taken.
No. The number of rays shot per sample does not depend on anything but
the count value. The only thing that influences which directions from the
table are taken is that when 'normal on' is specified sample directions
behind the surface are omitted.
Christoph
--
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 28 Feb. 2003 _____./\/^>_*_<^\/\.______
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Now I'm really confused here... I have been thinking for years that the
count value only sets the upper limit of samples gathered and that the other
values determine when/if additional samples are taken (up to the count
value).
With very low error_bound values (like 0.1) POV-Ray generally needs much
more time to render a scene compared to very high error_bound values (like
2.5). What on earth would take POV-Ray so much time? I guess it it's
gathering more samples.....
Please explain, maybe I might learn something!
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