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Hi all! I've been using Radiosity every now and then, but am not quiet
up-to-date with that clipping-thingy which was removed now in the latest
version. Anyone care to elaborate and perhaps post an example pic of
radiosity in 3.5 and 3.6? I'd like to know if I have to to some new
radiosity-tests to update a page on my website, but for that, I'd need to
know what exactly this clipping did...
Thanks in advance,
Tim
--
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>
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Tim Nikias v2.0 wrote:
> Hi all! I've been using Radiosity every now and then, but am not quiet
> up-to-date with that clipping-thingy which was removed now in the latest
> version. Anyone care to elaborate and perhaps post an example pic of
> radiosity in 3.5 and 3.6? I'd like to know if I have to to some new
> radiosity-tests to update a page on my website, but for that, I'd need to
> know what exactly this clipping did...
The clipping in 3.5 reduced the color of radiosity prediction values
calculated by ra_average_near() to [0..1]. This means that in scenes
which contain very bright areas results may differ - of course not in
direct appearance, there it will always be color rgb <1,1,1>. Note this
is different from what you can do with max_sample - this limits the
brightness of samples when taking them in ra_gather().
In practical use you will mostly observe differences with scenes using
higher recursion limits combined with strong light, for example a room
illuminated by sunlight coming through a small window. And of course
this is also important when dealing with high dynamic range image output
(although this is not yet possible in official POV or unofficial
versions currently available).
Kari Kivisalo posted a really quite minimal example some time ago:
Subject: Clipped radiosity samples
Date: Tue, 04 Mar 2003 16:37:49 +0200
Newsgroups: povray.advanced-users
From: Kari Kivisalo
news://news.povray.org/3E64BA3D.883AE539@luxlab.com
http://news.povray.org/3E64BA3D.883AE539@luxlab.com
Subject: Clipped radiosity samples
Date: Wed, 05 Mar 2003 17:20:39 +0200
Newsgroups: povray.binaries.images
From: Kari Kivisalo
news://news.povray.org/3E6615C7.EE9E97E9@luxlab.com
http://news.povray.org/3E6615C7.EE9E97E9@luxlab.com
Christoph
--
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 01 May. 2004 _____./\/^>_*_<^\/\.______
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> The clipping in 3.5 reduced the color of radiosity prediction values
> calculated by ra_average_near() to [0..1]. This means that in scenes
> which contain very bright areas results may differ - of course not in
> direct appearance, there it will always be color rgb <1,1,1>. Note this
> is different from what you can do with max_sample - this limits the
> brightness of samples when taking them in ra_gather().
>
> In practical use you will mostly observe differences with scenes using
> higher recursion limits combined with strong light, for example a room
> illuminated by sunlight coming through a small window. And of course
> this is also important when dealing with high dynamic range image output
> (although this is not yet possible in official POV or unofficial
> versions currently available).
Ah, thanks. That technical part at the beginning was a little over my head,
as I am not firm in the source of POV-Ray. Still, with spending some thought
and common sense I could make sense of it. A description well done, I must
say! :-)
I'll have to do some quick tests to figure if I've thought correctly, but
what you're implying is that in 3.5, Radiosity was clipped and thus, a
bright spot coming through a window wouldn't illuminate the room (via pure
radiosity, that is) to an extent which would have been more real, right? I'm
quiet fuzzy about where, what and when it gets clipped, but I think I have a
clue where to start experimenting now. And its always fun to experiment with
POV. :-)
Thanks again,
Tim
--
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>
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Tim Nikias v2.0 wrote:
>
> Ah, thanks. That technical part at the beginning was a little over my head,
> as I am not firm in the source of POV-Ray. Still, with spending some thought
> and common sense I could make sense of it.
Well, for successfully using radiosity some understanding of the inner
workings is quite useful.
> I'll have to do some quick tests to figure if I've thought correctly, but
> what you're implying is that in 3.5, Radiosity was clipped and thus, a
> bright spot coming through a window wouldn't illuminate the room (via pure
> radiosity, that is) to an extent which would have been more real, right?
That's about it. Note this effect really is not very important in a lot
of cases - i don't think any of the official sample scenes using
radiosity looks significantly different in 3.6.
Christoph
--
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 01 May. 2004 _____./\/^>_*_<^\/\.______
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Tim Nikias v2.0 wrote:
> Hi all! I've been using Radiosity every now and then, but am not quiet
> up-to-date with that clipping-thingy which was removed now in the latest
> version. Anyone care to elaborate and perhaps post an example pic of
> radiosity in 3.5 and 3.6? I'd like to know if I have to to some new
> radiosity-tests to update a page on my website, but for that, I'd need to
> know what exactly this clipping did...
>
> Thanks in advance,
> Tim
Tim, for a practical example look in p.b.i. I just posted an image explaining it~
-Sam Benge
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> Tim, for a practical example look in p.b.i. I just posted an image
explaining it~
Yup, just seen it. Thanks for sharing!
Regards,
Tim
--
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>
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