absorption and scattering coefficients for liquids
absorption and scattering coefficients for liquids
Jensen has a nice paper up on his site with a table full of absorption and scattering coefficients for many liquids - wine, coffee, milk etc..
http://graphics.ucsd.edu/~henrik/papers ... roperties/
The values are in units of 10^-2 mm^-1,
so i think you need to multiply them by 10 to get to the m^-1 that indigo uses now.
EDIT: the scattering coefficient can be used as is, once u have multiplied by 10. To get the absorption coefficient, subtract the scattering coefficient from the extinction coefficient (and multiply by 10).
Note that i have only implemented uniform scattering, so non-uniform scatters will not look 100% correct yet.
I haven't tried this data yet, if u get any results, pls post them!
nik
http://graphics.ucsd.edu/~henrik/papers ... roperties/
The values are in units of 10^-2 mm^-1,
so i think you need to multiply them by 10 to get to the m^-1 that indigo uses now.
EDIT: the scattering coefficient can be used as is, once u have multiplied by 10. To get the absorption coefficient, subtract the scattering coefficient from the extinction coefficient (and multiply by 10).
Note that i have only implemented uniform scattering, so non-uniform scatters will not look 100% correct yet.
I haven't tried this data yet, if u get any results, pls post them!
nik
Last edited by OnoSendai on Tue Jan 16, 2007 6:58 pm, edited 1 time in total.
Hi,
super link really interesting!
Right now I have a lot of crash tryzingHi nik,
super link really interesting!
I am just playing with this and right now I have a lot of crash trying to render a glass of Merlot wine!
I do not know where the problems are coming from, I also use the 07 exporter, and I will investigate this more in detail.
At this point I have some questions:
@all:
1- Does anybody here achieve some good results with this?
2- What about the units in Blender?
I offen import obj files from CAD program, and in this case the units are in mm, so should I scale the model?
3- Does the sss function work with all lights (map, sunlight, emitters)?
Thanks in advance, regards
Phil
super link really interesting!
Right now I have a lot of crash tryzingHi nik,
super link really interesting!
I am just playing with this and right now I have a lot of crash trying to render a glass of Merlot wine!
I do not know where the problems are coming from, I also use the 07 exporter, and I will investigate this more in detail.
At this point I have some questions:
@all:
1- Does anybody here achieve some good results with this?
2- What about the units in Blender?
I offen import obj files from CAD program, and in this case the units are in mm, so should I scale the model?
3- Does the sss function work with all lights (map, sunlight, emitters)?
Thanks in advance, regards
Phil
I would love to test some milk or wine too,
but I feel somehow stupid with all these terms I don't understand
perhaps somebody could tell me how to translate the values from the Table into a Indigo material...
so what exactly are:
- Extinction Coefficient
- Scattering Coefficient
- Average Cosine
- % RMS Error
in Indigo language???
The first three are RGB values but I only see two possibilities for RGB in Indigo:
<scattering_coefficient_spectrum>
<absorption_coefficient_spectrum>
but I feel somehow stupid with all these terms I don't understand
perhaps somebody could tell me how to translate the values from the Table into a Indigo material...
so what exactly are:
- Extinction Coefficient
- Scattering Coefficient
- Average Cosine
- % RMS Error
in Indigo language???
The first three are RGB values but I only see two possibilities for RGB in Indigo:
<scattering_coefficient_spectrum>
<absorption_coefficient_spectrum>
polygonmanufaktur.de
Here is a render of milk inside glass:
edit: The medium def:
edit: The medium def:
Code: Select all
<medium>
<name>milk_scattering_medium</name>
<ior>1.35</ior>
<cauchy_b_coeff>0.0</cauchy_b_coeff>
<precedence>10</precedence>
<absorption_coefficient_spectrum>
<rgb>
<rgb>0.001 0.003 0.013</rgb>
</rgb>
</absorption_coefficient_spectrum>
<subsurface_scattering>
<scattering_coefficient_spectrum>
<rgb>
<rgb>11.873 13.293 14.589</rgb>
</rgb>
</scattering_coefficient_spectrum>
<phase_function>
<uniform/>
</phase_function>
</subsurface_scattering>
</medium>
OK... I read Nick's first post again, and think I now understand how to get
<scattering_coefficient_spectrum> & <absorption_coefficient_spectrum> set
So far so good
So I tried to get a glass Merlot & Chardonnay rendered using the following mediums:
Chardonnay
Merlot
Here are some quick Renderings:
doesn't look very promissing at the moment... I realy hope I did something wrong
<scattering_coefficient_spectrum> & <absorption_coefficient_spectrum> set
So far so good
So I tried to get a glass Merlot & Chardonnay rendered using the following mediums:
Chardonnay
Code: Select all
<medium>
<name>wine</name>
<ior>1.33</ior>
<cauchy_b_coeff>0.003</cauchy_b_coeff>
<absorption_coefficient_spectrum>
<rgb>
<rgb>0.7586 1.6429 1.9196</rgb>
</rgb>
</absorption_coefficient_spectrum>
<precedence>4</precedence>
<subsurface_scattering>
<scattering_coefficient_spectrum>
<rgb>
<rgb>0.053 0 0</rgb>
</rgb>
</scattering_coefficient_spectrum>
<phase_function>
<uniform><value>0</value></uniform>
</phase_function>
</subsurface_scattering>
</medium>
Merlot
Code: Select all
<medium>
<name>wine</name>
<ior>1.33</ior>
<cauchy_b_coeff>0.0</cauchy_b_coeff>
<absorption_coefficient_spectrum>
<rgb>
<rgb>0.1547 0.1701 0.3443</rgb>
</rgb>
</absorption_coefficient_spectrum>
<precedence>10</precedence>
<subsurface_scattering>
<scattering_coefficient_spectrum>
<rgb>
<rgb>0.030 0.047 0.069</rgb>
</rgb>
</scattering_coefficient_spectrum>
<phase_function>
<uniform><value>0</value></uniform>
</phase_function>
</subsurface_scattering>
</medium>
doesn't look very promissing at the moment... I realy hope I did something wrong
polygonmanufaktur.de
hmmm... you did multiply the scattering_coefficient_spectrum AND the scattering_coefficient_spectrum by 10.ryjo wrote:ZomB,
I think your absorption_coefficient_spectrum is too low. This is what I get for Merlot:
absorption_coefficient_spectrum: 7.586 16.429 19.196
scattering_coefficient_spectrum: 0.053 0 0
I haven't tested this though...
Nicks first post tells only about multiplying scattering_coefficient_spectrum
OK I' try to Render Some Wine Over Night the way you say
polygonmanufaktur.de
Both the coefficients should be mutliplied by 10, i've added a clarification to the first post now.
See the glass test post: http://www.indigorenderer.com/joomla/fo ... .php?t=637 for information on how to model the glass correctly for indigo.
You also need to make sure your glasses are the correct size, bearing in mind that indigo units are meters.
See the glass test post: http://www.indigorenderer.com/joomla/fo ... .php?t=637 for information on how to model the glass correctly for indigo.
You also need to make sure your glasses are the correct size, bearing in mind that indigo units are meters.
Sorry to tell you dude, but it seems to crash with env_maps too, and also if you try to illuminate the Scene with a background Spectrum thing without other lightsourcesOnoSendai wrote:Hi, apparently there are crashes with SSS and sunlight, so if ur using sunlight, try using a mesh emitter instead (it will render faster as well)
At the moment I still use the old Exporter from BlackLizard, and edit the XML by Hand... after understanding the new medium system its quite easyCamox wrote:@ZomB
Nevertheless, this already looks much better.
Have you provided with Blender or with c4d and xml edited ?
Learning Blender is still on my list, but I'm working on a big C4D (School) Project atm,
after this is done I move to Blender...
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polygonmanufaktur.de
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