Subject:
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Re: HDRI and radiosity
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Newsgroups:
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lugnet.cad.ray
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Date:
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Wed, 31 Mar 2004 14:13:45 GMT
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Viewed:
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1944 times
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"Vince" <Vincent05@gmx.de> wrote in message news:Hv4Ls6.19y5@lugnet.com...
> Hi again,
> I'm still working on a good way to use hdri with MLCad pictures. And I • found out
> that grey is a "bad" color. Pictures with grey models are always too dark. • I can
> only fix this if I place additional light sources. I don't know the reason • yet
> but I think it has something to do with the color palette that is normally • used
> in PovRay. I have replaced the colors with those that are used in the • radiosity
> includes from digitalbricks.nl. And surprise...lights without any light • source.
> But - no light without shadow. Normal grey now looks like chrome. Using • other
> colors than grey in my model gives me the brilliance I want. Here are • some
> examples for the things I found out yet:
Hi Vince,
I would like to help you, this also affects me and the #include file I have
written.
I would like to know what you did with the backgound. Is it a skysphere with
a picture on it? Because if that is so, this affects the colours of the
bricks and the amount of light.
The original "HDI" code containt a skysphere like this:
sky_sphere {
pigment {
gradient -y
color_map {
[ 0.500000 rgb 1.25 ]
[ 1.000000 rgb <0.55, 0.77, 1.1> ]
}
}
As you can see the first colour has a value higher than 1. This means that
it (sort of) radiates light. The same goes for the second colour (blue-ish).
This also has a (just one this time) value higher than 1.
If you use values <=1 the render will be considerably darker. If you used a
picture on a skysphere the colours are per definition smaller than 1 so the
render will be darker.
The only way to change this is to add one or more lights.
Try to use area lights; these will give you a soft shadow. Or, if you don't
want shadows at all, use shadowless lights.
I have lowered the refection of the colours myself and if you download the
radiosity files now you will get less refection and a better rubber colour
:-)
Hope this helps.
Jeroen
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Message is in Reply To:
 | | HDRI and radiosity
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| Hi again, I'm still working on a good way to use hdri with MLCad pictures. And I found out that grey is a "bad" color. Pictures with grey models are always too dark. I can only fix this if I place additional light sources. I don't know the reason (...) (20 years ago, 25-Mar-04, to lugnet.cad.ray, FTX)
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