I've just started a radiosity render and noticed right off the bat that
things are way way too bright in what has been rendered... the same thing
without radiosity on renders just fine light-wise...

What should I modify first... light defs with their fade_power and
fade_distances or the radiosity parameters?

Thanks,
Robert J Becraft
aka cas### [at] aolcom

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Robert J Becraft <cas### [at] aolcom> wrote:
> What should I modify first... light defs with their fade_power and
> fade_distances or the radiosity parameters?

  Try modifying #default { finish { diffuse ... } } and
global_settings { radiosity { brightness ... } } until you find
a good combination which gives you the best brigthness for illuminated
and shadowed parts.
  (Note that making radiosity brightness too large will give you rather
unrealistic lighting, so don't raise it too much.)

-- 
#macro N(D)#if(D>99)cylinder{M()#local D=div(D,104);M().5,2pigment{rgb M()}}
N(D)#end#end#macro M()<mod(D,13)-6mod(div(D,13)8)-3,10>#end blob{
N(11117333955)N(4254934330)N(3900569407)N(7382340)N(3358)N(970)}//  - Warp -

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3d6d58d1$1@news.povray.org...
> What should I modify first... light defs with their fade_power and
> fade_distances or the radiosity parameters?

Hint : always work with radiosity turned on and use something low for the
tests, like count 30 error_bound 1. Then put a switch in the scene so that
you can use better settings for quality tests and final renders.
That way, you can tune your lighting as the scene requires it. I personally
find lighting scenes with radiosity much easier than without because it's
often possible to get away with one light only. Otherwise there are no
specific rules for radiosity lighting. Jaime's light macros for artificial
lights, for instance, use extremely bright colors and very small
fade_distance but natural lighting can use very standard lights.
Note that higher recursion levels tend to wash out the scene if it has
little contrast per se (I keep it at 1 unless the scene requires something
higher). The brightness parameter can be used to enhance the radiosity
effect though it may look unnatural if too high. Rad scenes can also benefit
from some post-processing like tone level adjustment to get a richer and
more pleasant tone range.

G.


--
**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters

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3d6d58d1$1@news.povray.org...
> I've just started a radiosity render and noticed right off the bat that
> things are way way too bright in what has been rendered... the same thing
> without radiosity on renders just fine light-wise...
>
> What should I modify first... light defs with their fade_power and
> fade_distances or the radiosity parameters?

Reading Warp's comment I realise that I forgot to add that when using
radiosity it is preferable to have ambient set at 0 (using #default). The
default ambient 0.1 may also explains why it looks too bright. Let the
radiosity do the work.

G.

--
**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters

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On Wed, 28 Aug 2002 19:12:16 -0400 Robert J Becraft wrote:

>I've just started a radiosity render and noticed right off the bat that
>things are way way too bright in what has been rendered... the same thing
>without radiosity on renders just fine light-wise...

  While not quite a tutorial, you can read and view Warp's radiosity
example page at:

http://www.students.tut.fi/~warp/pics/Radiosity_test2/

  I also found the link to Warp's comments page to be of value when it
comes to setting ambient to 0 (zero). There is a disclaimer that some of
what he has written applies to POV-Ray 3.1, but I still found the
examples interesting.

-- 
Alan
ako### [at] povrayorg
a k o n g <at> p o v r a y <dot> o r g

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> Reading Warp's comment I realise that I forgot to add that when using
> radiosity it is preferable to have ambient set at 0 (using #default).

Or using

global_settings {
ambient_light 0
}

 - Slime
[ http://www.slimeland.com/ ]

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> global_settings {
> ambient_light 0
> }


Better to use the #default option for ambient in textures.  If you set
global ambient to 0, you can't create visible light sources for radiosity
using ambient.

-tgq

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> Better to use the #default option for ambient in textures.  If you set
> global ambient to 0, you can't create visible light sources for radiosity
> using ambient.

Funny you mention that; I just now ran into that problem again and realized
why Gilles said that =)

In the past I just set ambient_light .00001 and then used ambient 1/.00001
for bright objects.

 - Slime
[ http://www.slimeland.com/ ]

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Alan Kong <ako### [at] povraywwwspamcomorg> wrote:
> There is a disclaimer that some of
> what he has written applies to POV-Ray 3.1

  Actually the whole text applies almost exclusively to POV-Ray 3.1.
The radiosity has changed so much in 3.5 that almost nothing of that
text applies anymore.

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -

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Robert J Becraft wrote:
 >
> I've just started a radiosity render and noticed right off the bat that
> things are way way too bright in what has been rendered... the same thing
> without radiosity on renders just fine light-wise...
> 
> What should I modify first... light defs with their fade_power and
> fade_distances or the radiosity parameters?

I certainly wouldn't change the fade_power or fade_distance at this 
point! Altering the "physical" characteristics of your light will 
certainly change the lighting, but probably not in the way you want.

Radiosity effectively adds light to the scene (assuming that some 
already exists in the form of ambience or light_sources, of course). 
It's not surprising that a scene which is perfectly-lit by standard 
lighting would be too bright with radiosity added.

Consider using a default ambient 0, as the other posters have suggested 
(otherwise, radiosity will make EVERYTHING glow). If that doesn't help, 
the next easiest thing to do is simply to reduce the intensity of your 
lighting (letting the radiosity "fill in" for the missing 
illumination).. or alternatively, if none of your textures use a custom 
diffuse value, and you have a lot of lights, just lower the default 
diffuse value.

You could also lower the brightness in the radiosity block.. of course, 
at some point, this becomes counterproductive. The point of using 
radiosity is to have it be visible. ;)

It's usually a good idea to write and test your scenes with radiosity on 
all the time (even very low quality settings - say, count 10-30, 
error_bound 1 - will give you a rough idea of how the lighting will 
look). At the very least, do turn it on for the lighting tweaks, if not 
for the modeling.

-Xplo

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