lamp. The figure is supposed to be made of ivory.
I know that the values for subsurface { <R,G,B>, <R,G,B>} should be 

Light Transport does not give any values for ivory. Does anyone have any 
ideas how to fudge them?

Comments and ideas welcome.

-- 
Regards
     Stephen

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Stephen <mcavoys_at@aoldotcom> wrote:

> lamp. The figure is supposed to be made of ivory.
> I know that the values for subsurface { <R,G,B>, <R,G,B>} should be

> Light Transport does not give any values for ivory. Does anyone have any
> ideas how to fudge them?
>
> Comments and ideas welcome.
>
> --
> Regards
>      Stephen

Steven, I'm working on an SSLT how-to for the wiki and translated the materials
chart from that SSLT paper into the following textures (so I could see what they
really look like in POV-Ray). Maybe this will help you fudge some values for
ivory...

/*
From "A Practical Model for Subsurface Light Transport", Jensen, et. al.
-------------------------------------------------------------------------------
Material     Scattering          Absorbing                  Color (diffuse refl)
-------------------------------------------------------------------------------
Apple      = <2.29, 2.39, 1.97>, <0.0030, 0.0034, 0.046>   : <0.85, 0.84, 0.53>
Chicken1   = <0.15, 0.21, 0.38>, <0.015, 0.077, 0.19>      : <0.31, 0.15, 0.10>
Chicken2   = <0.19, 0.25, 0.32>, <0.018, 0.088, 0.20>      : <0.32, 0.16, 0.10>
Cream      = <7.38, 5.47, 3.15>, <0.0002, 0.0028, 0.0163>  : <0.98, 0.90, 0.73>
Ketchup    = <0.18, 0.07, 0.03>, <0.061, 0.97, 1.45>       : <0.16, 0.01, 0.00>
Marble     = <2.19, 2.62, 3.00>, <0.0021, 0.0041, 0.0071>  : <0.83, 0.79, 0.75>
Potato     = <0.68, 0.70, 0.55>, <0.0024, 0.0090, 0.12>    : <0.77, 0.62, 0.21>
Skimmilk   = <0.70, 1.22, 1.90>, <0.0014, 0.0025, 0.0142>  : <0.81, 0.81, 0.69>
Skin1      = <0.74, 0.88, 1.01>, <0.032, 0.17, 0.48>       : <0.44, 0.22, 0.13>
Skin2      = <1.09, 1.59, 1.79>, <0.013, 0.070, 0.145>     : <0.63, 0.44, 0.34>
Spectralon = <11.6, 20.4, 14.9>, <0.00, 0.00, 0.00>        : <1.00, 1.00, 1.00>
Wholemilk  = <2.55, 3.21, 3.77>, <0.0011, 0.0024, 0.014>   : <0.91, 0.88, 0.76>
-------------------------------------------------------------------------------
*/

// components
#declare P_SSLT_Apple = pigment { rgb <0.85, 0.84, 0.53> }
#declare F_SSLT_Apple =
   finish { subsurface { <2.29, 2.39, 1.97>, <0.0030, 0.0034, 0.046> } }

#declare P_SSLT_Chicken1 = pigment { rgb <0.31, 0.15, 0.10> }
#declare F_SSLT_Chicken1 =
   finish { subsurface { <0.15, 0.21, 0.38>, <0.015, 0.077, 0.19> } }

#declare P_SSLT_Chicken2 = pigment { rgb <0.32, 0.16, 0.10> }
#declare F_SSLT_Chicken2 =
   finish { subsurface { <0.19, 0.25, 0.32>, <0.018, 0.088, 0.20> } }

#declare P_SSLT_Cream = pigment { rgb  <0.98, 0.90, 0.73> }
#declare F_SSLT_Cream =
   finish { subsurface { <7.38, 5.47, 3.15>, <0.0002, 0.0028, 0.0163> } }

#declare P_SSLT_Ketchup = pigment { rgb  <0.16, 0.01, 0.00> }
#declare F_SSLT_Ketchup =
   finish { subsurface { <0.18, 0.07, 0.03>, <0.061, 0.97, 1.45> } }

#declare P_SSLT_Marble = pigment { rgb <0.83, 0.79, 0.75> }
#declare F_SSLT_Marble =
   finish { subsurface { <2.19, 2.62, 3.00>, <0.0021, 0.0041, 0.0071> } }

#declare P_SSLT_Potato = pigment { rgb <0.77, 0.62, 0.21> }
#declare F_SSLT_Potato =
   finish { subsurface { <0.68, 0.70, 0.55>, <0.0024, 0.0090, 0.12>  } }

#declare P_SSLT_SkimMilk = pigment { rgb <0.81, 0.81, 0.69> }
#declare F_SSLT_SkimMilk =
   finish { subsurface {<0.70, 1.22, 1.90>, <0.0014, 0.0025, 0.0142> } }

#declare P_SSLT_Skin1 = pigment { rgb <0.44, 0.22, 0.13> }
#declare F_SSLT_Skin1 =
   finish { subsurface { <0.74, 0.88, 1.01>, <0.032, 0.17, 0.48> } }

#declare P_SSLT_Skin2 = pigment { rgb <0.63, 0.44, 0.34> }
#declare F_SSLT_Skin2 =
   finish { subsurface { <1.09, 1.59, 1.79>, <0.013, 0.070, 0.145> } }

#declare P_SSLT_Spectralon = pigment { rgb <1.00, 1.00, 1.00> }
#declare F_SSLT_Spectralon =
   finish { subsurface { <11.6, 20.4, 14.9>, <0.00, 0.00, 0.00> } }

#declare P_SSLT_Wholemilk = pigment { rgb <0.91, 0.88, 0.76> }
#declare F_SSLT_Wholemilk =
   finish { subsurface { <2.55, 3.21, 3.77>, <0.0011, 0.0024, 0.014> } }

// SSLT base textures
#declare T_SSLT_Apple = texture {
   pigment { P_SSLT_Apple }
   finish { F_SSLT_Apple }
}

#declare T_SSLT_Chicken1 = texture {
   pigment { P_SSLT_Chicken1 }
   finish { F_SSLT_Chicken1 }
}

#declare T_SSLT_Chicken2 = texture {
   pigment { P_SSLT_Chicken2 }
   finish { F_SSLT_Chicken2 }
}

#declare T_SSLT_Cream = texture {
   pigment { P_SSLT_Cream }
   finish { F_SSLT_Cream }
}

#declare T_SSLT_Ketchup = texture {
   pigment { P_SSLT_Ketchup }
   finish { F_SSLT_Ketchup }
}

#declare T_SSLT_Marble = texture {
   pigment { P_SSLT_Marble }
   finish { F_SSLT_Marble }
}

#declare T_SSLT_Potato = texture {
   pigment { P_SSLT_Potato }
   finish { F_SSLT_Potato }
}

#declare T_SSLT_SkimMilk = texture {
   pigment { P_SSLT_SkimMilk }
   finish { F_SSLT_SkimMilk }
}

#declare T_SSLT_Skin1 = texture {
   pigment { P_SSLT_Skin1 }
   finish { F_SSLT_Skin1 }
}

#declare T_SSLT_Skin2 = texture {
   pigment { P_SSLT_Skin2 }
   finish { F_SSLT_Skin2 }
}

#declare T_SSLT_Spectralon = texture {
   pigment { P_SSLT_Spectralon }
   finish { F_SSLT_Spectralon }
}

#declare T_SSLT_Wholemilk = texture {
   pigment { P_SSLT_Wholemilk }
   finish { F_SSLT_Wholemilk }
}

-------------------------------------------------
www.McGregorFineArt.com

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On 12/02/2011 7:22 PM, Robert McGregor wrote:
> Steven, I'm working on an SSLT how-to for the wiki and translated the materials
> chart from that SSLT paper into the following textures (so I could see what they
> really look like in POV-Ray). Maybe this will help you fudge some values for
> ivory...


I already extracted those figures into Excel so I could play with them 
but you seemed to have missed out the Relative index of refraction. 1.3 
for most of the materials and 1.5 for Marble (I assume that it is 
important). I also found it useful to be able to change the specular and 
roughness in my material.
I did not realise that it was subsurface { Scattering , Absorbing} so 
that will help a lot, I think.


-- 
Regards
     Stephen

Post a reply to this message

On 02/12/2011 01:22 PM, Stephen wrote:

> lamp. The figure is supposed to be made of ivory.
> I know that the values for subsurface { <R,G,B>, <R,G,B>} should be

> Light Transport does not give any values for ivory. Does anyone have any
> ideas how to fudge them?
> 
> Comments and ideas welcome.
> 
you've been doing some nice character work lately ... btw: had a lamp
fairly close to what you've got in the shop several years ago except her
arms were more upwards and the lamp globe was opalescent

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On 12/02/2011 8:21 PM, Jim Holsenback wrote:
> you've been doing some nice character work lately ...




> btw: had a lamp
> fairly close to what you've got in the shop several years ago except her
> arms were more upwards and the lamp globe was opalescent


very fashionable and out of my price range. :-(
The complement is quite embarrassing as the last couple of models have 

face is too modern and the hair style should be a bob but I just wanted 
something quick.

-- 
Regards
     Stephen

Post a reply to this message

Stephen <mcavoys_at@aoldotcom> wrote:
> I already extracted those figures into Excel so I could play with them
> but you seemed to have missed out the Relative index of refraction. 1.3
> for most of the materials and 1.5 for Marble (I assume that it is
> important). I also found it useful to be able to change the specular and
> roughness in my material.

Well, the refraction would be at the material/object level, as part of the
interior. Water is IOR ~1.3, glass, jade, and pearl are ~1.5, and diamond is
~2.4, not sure what ivory would be.

Anyway, these are just textures that I defined as base SSLT-only textures.
I've noticed that the current SSLT implementation doesn't play well with complex
pigments like color_maps or image_maps; it just seems to ignore them. So I've
been experimenting with layered and patterned textures instead of just pure
SSLT, getting results like these (with spec, roughness, etc in non-SSLT
layers/patterns).

-------------------------------------------------
www.McGregorFineArt.com

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"Robert McGregor" <rob### [at] mcgregorfineartcom> wrote:
> not sure what ivory would be.

Okay, I just found this extensive IOR listing with ivory at IOR 1.54:

http://interactagram.com/physics/optics/refraction/

Post a reply to this message

>
> Well, the refraction would be at the material/object level, as part of the
> interior. Water is IOR ~1.3, glass, jade, and pearl are ~1.5, and diamond is
> ~2.4, not sure what ivory would be.

> Okay, I just found this extensive IOR listing with ivory at IOR 1.54:

http://interactagram.com/physics/optics/refraction/

Excellent! Just bookmarked it, thanks.

> Anyway, these are just textures that I defined as base SSLT-only textures.

That's a problem with using a modeller, I don't know these coding 
tricks. :-( I thought...

> I've noticed that the current SSLT implementation doesn't play well with complex
> pigments like color_maps or image_maps; it just seems to ignore them. So I've
> been experimenting with layered and patterned textures instead of just pure
> SSLT, getting results like these (with spec, roughness, etc in non-SSLT
> layers/patterns).
>

The Ketchup would make a good marble but I would not like to drink the 
wholemilk. ;-)

The settings I used for my ivory were:
IOR 1.5
colour rgbft <0.914,0.906,0.620,0.000,0.000>
ambient     rgb <0.100,0.100,0.0945>
subsurface { <3,3,2> * 
<0.914,0.906,0.620>,<0.914,0.906,0.620>*<0.914,0.906,0.620>/1000 }



-- 
Regards
     Stephen

Post a reply to this message

Am 12.02.2011 21:11, schrieb Stephen:

> but you seemed to have missed out the Relative index of refraction. 1.3
> for most of the materials and 1.5 for Marble (I assume that it is
> important).

Yup, 'tis.

Post a reply to this message

> lamp. The figure is supposed to be made of ivory.
> I know that the values for subsurface { <R,G,B>, <R,G,B>} should be

> Light Transport does not give any values for ivory. Does anyone have any
> ideas how to fudge them?
>
> Comments and ideas welcome.
>

You may try the values for some bone or bone like materials. Ivory is 
after all a kind of bone.

As it is now, the figurine lamp looks more like brass.


Alain

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