I'm trying to make an approximation of black body radiation (glowing red-hot
-> white hot -> blue hot)...

Getting the color down was easy.

The problem is, I want to use radiosity to reflect the light coming from the
heated object, but either the object turns pure white before it should and
the ambient light looks correct, OR the object color looks right and the
ambient light is way too low.  i've messed with radiosity settings and
plenty of ambient functions, but I can't get a good result.

Is it possible to have the ambient light turned waaaay up, but not have it
affect the object pigment---or more accurately, how it renders the pigment?

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Budgery wrote:
> Is it possible to have the ambient light turned waaaay up, but not have it
> affect the object pigment---or more accurately, how it renders the pigment?

Try to use 2 objects: One with no_image and the correct value for 
ambient and the other with the correct pigment, no_reflection and no_shadow?

Ayk

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> Try to use 2 objects: One with no_image and the correct value for
> ambient and the other with the correct pigment, no_reflection and no_shadow?
>
> Ayk

Tried it.  Don't work.  the no_image tag makes povray completely ignore the
ambient, even when turned up to 10 billion.

I also tried having a lightsource with looks_like.  Terrible results.

I'd like to have a macro that just defines a texture to put on top of the
existing texture of any pre-existing object (low temperatures, the original
texture shows through fully, high temperatures, the ambient and heat color
take over)...but if its not possible, then its not possible.

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It seems, you should rise the brightness inside the radiosity settings to
values higher than 1.


Norbert Kern



"Budgery" <bud### [at] yahoocom> wrote:
> I'm trying to make an approximation of black body radiation (glowing red-hot
> -> white hot -> blue hot)...
>
> Getting the color down was easy.
>
> The problem is, I want to use radiosity to reflect the light coming from the
> heated object, but either the object turns pure white before it should and
> the ambient light looks correct, OR the object color looks right and the
> ambient light is way too low.  i've messed with radiosity settings and
> plenty of ambient functions, but I can't get a good result.
>
> Is it possible to have the ambient light turned waaaay up, but not have it
> affect the object pigment---or more accurately, how it renders the pigment?

Post a reply to this message

"Norbert Kern" <nor### [at] t-onlinede> wrote:
> It seems, you should rise the brightness inside the radiosity settings to
> values higher than 1.
>
>
> Norbert Kern
>
>
>

Yeah, I tried that, too.  It looked the best of all of my attemps, but it
still wasn't quite right.  Plus, I'd like to have normal looking radiosity
in the rest of the scene instead of everything being super bright.  Oh
well.  Thanks for all the input, though!

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In article <web.4162efd0ca2b83faa1fd027f0@news.povray.org>,
 "Budgery" <bud### [at] yahoocom> wrote:

> The problem is, I want to use radiosity to reflect the light coming from the
> heated object, but either the object turns pure white before it should and
> the ambient light looks correct, OR the object color looks right and the
> ambient light is way too low.  i've messed with radiosity settings and
> plenty of ambient functions, but I can't get a good result.
> 
> Is it possible to have the ambient light turned waaaay up, but not have it
> affect the object pigment---or more accurately, how it renders the pigment?

The problem is the limited range of standard image formats. When you 
turn the ambient up to a realistic level, it is far brighter than 
"white", so it gets clipped. You could hack a custom transfer function 
into the source or use a patched version that includes HDR output and/or 
an exposure function (I think MegaPOV has both). Also, you could "put on 
sunglasses"...place a sphere with a filtering texture (say, rgbf < 0, 0, 
0, 1/255>) to get the high-brightness areas, and combine the images with 
the different luminance magnitudes in a separate program.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/

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