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Does anyone have a link to a list of known diffuse coefficients? I would
like to know what diffuse to use without having to guess each time. Thanks
in advance for any help.
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"Tony[B]" wrote:
>
> Does anyone have a link to a list of known diffuse coefficients? I would
> like to know what diffuse to use without having to guess each time. Thanks
> in advance for any help.
This might be of help:
http://www.cs.utah.edu/~bes/graphics/spectra/
However, I haven't read everything in there so I'm not quite sure I
grasp the full meaning of these numbers.
--
Francois Labreque | And a four year old carelessly banging on a toy
flabreque | piano is not only 'music', it's probably the last
@ | moment of 'artistic purity' they'll ever enjoy
videotron.ca | before outside influences start corrupting their
| expression. - Chris R.
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Thank you, that link was so helpful! :)
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> However, I haven't read everything in there so I'm not quite sure I
> grasp the full meaning of these numbers.
On closer inspection, neither do I. Is the Chrominance the RGB and the
Luminance the Diffuse? What about the other numbers?
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Known diffuse coefficients?
I was no where near that neighborhood!
I plead absolute innocence. A clear case of mistaken
identity!!!
I will fight this until my last dying brea......
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"Tony[B]" wrote:
>
> > However, I haven't read everything in there so I'm not quite sure I
> > grasp the full meaning of these numbers.
>
> On closer inspection, neither do I. Is the Chrominance the RGB and the
> Luminance the Diffuse?
That's what I think it is.
> What about the other numbers?
I think it's the "luminance" broken down by wavelength (400 nm being the
wavelength of red light)
Could someone who understands this enlighten us (no pun intended)?
Kari, maybe?
--
Francois Labreque | And a four year old carelessly banging on a toy
flabreque | piano is not only 'music', it's probably the last
@ | moment of 'artistic purity' they'll ever enjoy
videotron.ca | before outside influences start corrupting their
| expression. - Chris R.
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On Thu, 01 Mar 2001 08:08:14 -0500, Francois Labreque wrote:
>
>
>"Tony[B]" wrote:
>>
>> > However, I haven't read everything in there so I'm not quite sure I
>> > grasp the full meaning of these numbers.
>>
>> On closer inspection, neither do I. Is the Chrominance the RGB and the
>> Luminance the Diffuse?
>
>That's what I think it is.
I thought Chroma and Luma were somehow related to Y/C in television, and
somewhat related to HSB.
--
Ron Parker http://www2.fwi.com/~parkerr/traces.html
My opinions. Mine. Not anyone else's.
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Francois Labreque wrote:
>
> I think it's the "luminance" broken down by wavelength (400 nm being the
> wavelength of red light)
>
Sorry, it's the otherway round: red light is about 700 nm,
bluelight at about 400 nm,
bigger than 700 nm are infra-red (then the whole radio thing)
smaller than 400 nm are ultraviolet (sp) then X-ray and so.
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"Tony[B]" wrote:
>
> Luminance the Diffuse?
Yes. I don't know how it's calculated from the spectral data but it's
close enough to be used as pov diffuse.
Here are some reference values. You can pretty much guess the diffuse
for other materials using these.
specular aluminum 0.95
new snow 0.75
concrete 0.40
vegetation (mean) 0.25
asphalt 0.07
______________________________________________________________________
Kari Kivisalo http://www.kivisalo.net
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OK, I know you know more about this stuff than the rest of us do... Here's
an example, taken from here
http://www.cs.utah.edu/~bes/graphics/spectra/19_WHITE.sd
# File: /usr/testbed/files/sdb//macbeth.sdb
# Material Class: MACBETH CHART
# Material Name: 19 WHITE
# Comment:
# white mccamy76 19 white
# NBS Index: 263 white
# Chromaticity: (0.309906, 0.317325, 0.372769) luminance 0.898767
# Coefficient of Extinction: 0.000000
# Index of Refraction: 0.000000
# Average Energy: 0.582036
246 <snip>long list</pins>
Now, the way I read is is:
texture {pigment {rgb <0.309906,0.317325,0.372769>} finish {ambient 0
diffuse 0.898767}}
What would "average energy" be, and how do I apply it to these numbers?
Thanks in advance, Kari.
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