POV-Ray : Newsgroups : povray.general : Radiosity help Server Time
1 Aug 2024 06:17:34 EDT (-0400)
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From: jhu
Subject: Re: Radiosity help
Date: 23 Apr 2006 12:10:00
Message: <web.444ba68113671ebca842a49e0@news.povray.org>
In some situations, yes. In real life, when you walk outdoors, things don't
have a blue tint. I'm trying to get that sense without having completely
dark shadows behind objects.

"Zeger Knaepen" <zeg### [at] povplacecom> wrote:
> "jhu" <nomail@nomail> wrote in message
> news:web.444b9d653e18951ea842a49e0@news.povray.org...
> > I'm trying to make an outdoor scene with a white object. I have a sky_sphere
> > that is basically a light blue. However, whenever I render with radiosity,
> > the object has a blue tint to it.
>
> isn't that exactly the point of radiosity?
>
> cu!
> --
> #macro G(b,e)b+(e-b)*C/50#end#macro _(b,e,k,l)#local C=0;#while(C<50)
> sphere{G(b,e)+3*z.1pigment{rgb G(k,l)}finish{ambient 1}}#local C=C+1;
> #end#end _(y-x,y,x,x+y)_(y,-x-y,x+y,y)_(-x-y,-y,y,y+z)_(-y,y,y+z,x+y)
> _(0x+y.5+y/2x)_(0x-y.5+y/2x)            // ZK http://www.povplace.com


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From: "Jérôme M. Berger"
Subject: Re: Radiosity help
Date: 23 Apr 2006 12:30:07
Message: <444bab8f@news.povray.org>
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jhu wrote:
> In some situations, yes. In real life, when you walk outdoors, things don't
> have a blue tint. I'm trying to get that sense without having completely
> dark shadows behind objects.
> 
	Actually, they do. However most of the times, when the sky is blue
enough for the effect to be visible, you've got the sun shining
yellow light on the scene which balances the blue. But if you look
closely at a pure white object in shadow, you should notice that it
has taken a blue cast.

		Jerome

- --
+------------------------- Jerome M. BERGER ---------------------+
|    mailto:jeb### [at] freefr      | ICQ:    238062172            |
|    http://jeberger.free.fr/     | Jabber: jeb### [at] jabberfr   |
+---------------------------------+------------------------------+
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From: Christoph Hormann
Subject: Re: Radiosity help
Date: 23 Apr 2006 12:40:03
Message: <e2gafd$ut4$1@chho.imagico.de>
jhu wrote:
> In some situations, yes. In real life, when you walk outdoors, things don't
> have a blue tint.

That's not right.  The blue tint you observe would also occurs in real 
life.  The reason why you find it unnatural is that you designed the 
scene (textures, lighting etc.) to look natural without radiosity and 
expect it to look the same with it.  This does not work.

You have the no_radiosity flag in MegaPOV to exclude certain objects 
from radiosity calculation but this is just a artistic feature without a 
  physical background.  If you want your render to look realistic you 
should design the scene to look this way with radiosity and with sky.

Christoph

-- 
POV-Ray tutorials, include files, Landscape of the week:
http://www.imagico.de/ (Last updated 14 Mar. 2006)
MegaPOV with mechanics simulation: http://megapov.inetart.net/


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From: Tim Nikias
Subject: Re: Radiosity help
Date: 23 Apr 2006 12:48:50
Message: <444baff2$1@news.povray.org>
> I'm trying to make an outdoor scene with a white object. I have a
sky_sphere
> that is basically a light blue. However, whenever I render with radiosity,
> the object has a blue tint to it. Is there some way to keep the background
> color without it affecting the rest of the scene? I can't seem to find it
> in the doucmentation. Thanks

I'm thinking the gray_threshold in the radiosity-block was introduced for
just this.
But as others have already pointed out, the blue tint is actually realistic,
gray_threshold just takes the color out of the brightness.

Regards,
Tim

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


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From: jhu
Subject: Re: Radiosity help
Date: 23 Apr 2006 13:05:00
Message: <web.444bb39613671ebca842a49e0@news.povray.org>
Ok, that did it. Thanks!

"Tim Nikias" <JUSTTHELOWERCASE:timISNOTnikias(at)gmx.netWARE> wrote:
> > I'm trying to make an outdoor scene with a white object. I have a
> sky_sphere
> > that is basically a light blue. However, whenever I render with radiosity,
> > the object has a blue tint to it. Is there some way to keep the background
> > color without it affecting the rest of the scene? I can't seem to find it
> > in the doucmentation. Thanks
>
> I'm thinking the gray_threshold in the radiosity-block was introduced for
> just this.
> But as others have already pointed out, the blue tint is actually realistic,
> gray_threshold just takes the color out of the brightness.
>
> Regards,
> Tim
>
> --
> aka "Tim Nikias v2.0"
> Homepage: <http://www.nolights.de>


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From: Warp
Subject: Re: Radiosity help
Date: 23 Apr 2006 13:52:45
Message: <444bbeed@news.povray.org>
jhu <nomail@nomail> wrote:
> In real life, when you walk outdoors, things don't
> have a blue tint.

  Would you call the blue tint in this image unrealistic, non-real-life-like?

http://warp.povusers.org/sponza.jpg

-- 
                                                          - Warp


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From: jhu
Subject: Re: Radiosity help
Date: 23 Apr 2006 15:00:01
Message: <web.444bcde113671ebca842a49e0@news.povray.org>
No, just that mine wasn't realistic

Warp <war### [at] tagpovrayorg> wrote:
> jhu <nomail@nomail> wrote:
> > In real life, when you walk outdoors, things don't
> > have a blue tint.
>
>   Would you call the blue tint in this image unrealistic, non-real-life-like?
>
> http://warp.povusers.org/sponza.jpg
>
> --
>                                                           - Warp


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From: Warp
Subject: Re: Radiosity help
Date: 23 Apr 2006 15:18:14
Message: <444bd2f6@news.povray.org>
jhu <nomail@nomail> wrote:
> No, just that mine wasn't realistic

  Your image was probably realistic if you had set up a real-life scene
which was identical to your modelled scene.
  However, since your modelled scene was probably quite different from
what you usually see in real life, it was something unexpected, but not
unrealistic per se.

-- 
                                                          - Warp


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From: Trevor G Quayle
Subject: Re: Radiosity help
Date: 23 Apr 2006 22:05:00
Message: <web.444c31b213671ebcc8947640@news.povray.org>
"jhu" <nomail@nomail> wrote:
> I'm trying to make an outdoor scene with a white object. I have a sky_sphere
> that is basically a light blue. However, whenever I render with radiosity,
> the object has a blue tint to it. Is there some way to keep the background
> color without it affecting the rest of the scene? I can't seem to find it
> in the doucmentation. Thanks

The best way to do this (without using MegaPOV which has a no_radiosity
flag) is create large black sphere that encloses your enitre scene and give
it no_image, no_reflection and no_shadow attributes.  This wayit doesn't
interact with your scene at all, but it will block out the radiosity
effects of anything outside it(i.e.,the sky_sphere).

-tgq


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From: Alain
Subject: Re: Radiosity help
Date: 23 Apr 2006 23:34:45
Message: <444c4755@news.povray.org>
jhu nous apporta ses lumieres en ce 23/04/2006 11:29:
> I'm trying to make an outdoor scene with a white object. I have a sky_sphere
> that is basically a light blue. However, whenever I render with radiosity,
> the object has a blue tint to it. Is there some way to keep the background
> color without it affecting the rest of the scene? I can't seem to find it
> in the doucmentation. Thanks
> 
> 
If you take an outdoor photo with an interior film, everything will have a strong blue
cast. You 
don't notice it because your eyes are automaticaly compensating.
Optionaly, you can add a large white sphere with no_image. It will affect the
radiosity even if you 
can't see it. Also add no_reflection if you have any reflective object.
You can alter the colour of your object by making it a little yellow.

-- 
Alain
-------------------------------------------------
WARNING: The consumption of alcohol may leave you wondering what the hell happened to
your bra and 
panties.


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