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From: JRG
Subject: question concerning area lights, reflection blur et cetera...
Date: 23 Apr 2001 16:57:09
Message: <3ae49725@news.povray.org>
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Area lights are quite slow and relfection blur even more. Would it be so
difficult to make fast pre- (or post) processing area lights with some sort
of filter to blur the edge of the shadows? It would be much less accurate
but really faster. I saw something like that somewhere...
jrg
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From: Christoph Hormann
Subject: Re: question concerning area lights, reflection blur et cetera...
Date: 23 Apr 2001 17:11:48
Message: <3AE49A9D.4B3838BE@gmx.de>
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JRG wrote:
>
> Area lights are quite slow and relfection blur even more. Would it be so
> difficult to make fast pre- (or post) processing area lights with some sort
> of filter to blur the edge of the shadows? It would be much less accurate
> but really faster. I saw something like that somewhere...
> jrg
You can of course blur the whole picture or parts of it like with focal
blur, but to selectively blur the shadowlines would be quite impossible
and also would not look realistic, because the structures of objects and
textures should not be blurred.
It's part of the concept of raytracing that these things are quite slow,
using some kind of reflection maps like done in scanline renderers could
speed up reflection blur, but that would not be an all purpose solution.
Christoph
--
Christoph Hormann <chr### [at] gmx de>
IsoWood include, radiosity tutorial, TransSkin and other
things on: http://www.schunter.etc.tu-bs.de/~chris/
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From: Warp
Subject: Re: question concerning area lights, reflection blur et cetera...
Date: 24 Apr 2001 06:58:40
Message: <3ae55c60@news.povray.org>
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This might be possible with a slightly modified version of photon mapping...
--
char*i="b[7FK@`3NB6>B:b3O6>:B:b3O6><`3:;8:6f733:>::b?7B>:>^B>C73;S1";
main(_,c,m){for(m=32;c=*i++-49;c&m?puts(""):m)for(_=(
c/4)&7;putchar(m),_--?m:(_=(1<<(c&3))-1,(m^=3)&3););} /*- Warp -*/
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From: Nathan Kopp
Subject: Re: question concerning area lights, reflection blur et cetera...
Date: 24 Apr 2001 22:42:31
Message: <3ae63997$1@news.povray.org>
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"JRG" <jrg### [at] hotmailcom> wrote...
>
> "Warp" wrote
> > This might be possible with a slightly modified version of photon
> mapping...
> Lightflow supports this type of lights, ergo it would be possible to
> implement in an unofficial version of POV.
> Here's the quote from Lightflow's documentation:
> "Soft light [...]
> It simulates soft shadows using a simple zbuffering technique, and so it
is
> much faster than real area lights, even if it produces similar results.
I read a paper about a technique that would do this. (probably the same
algorithm that lightflow uses.) There was even a discussion on one of these
groups. The problem is that it only works with tesselated (all
triangle/polygon) scenes, because it works by doing an intersection test
with an 'expanded' version of the object, where each individual triangle is
scaled larger. This technique only works with convex objects, not with
concave objects. It works with triangle meshes because the mesh can be
treated as a collection of convex objects, and each one is scaled
individually. You currently can't do that with all POV scenes.
-Nathan
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