Multi layered SSS skin model

General questions about Indigo, the scene format, rendering etc...
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CoolColJ
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Multi layered SSS skin model

Post by CoolColJ » Mon Sep 03, 2007 11:48 pm

don't know if this has been posted before

http://graphics.ucsd.edu/papers/layered/

There are some values we can use I think.... seeing the different SSS layers , help understand how to do this in Indigo

there are RGB absorbtion and scattering values given in the PDF for epidermis, dermis, and the bloody dermis, the "g" value for Henyey Greenstein phase function, and layer thickness, but what's the "n" value for?

edit - "n" is the IOR :)

so it is time to test this one day, my old lightwave female head should do the trick 8)
This face model was rendered using a layered skin model described in this paper. The skin is composed of three layers: epidermis, dermis, and the bloody dermis. The scattering parameters for the individual layers are from measured data available in the medical physics literature. Note that the multilayered model gives the skin a less waxy look compared to the standard BSSRDF (dipole diffusion) based skin rendering shown below
Image
Last edited by CoolColJ on Tue Sep 04, 2007 12:19 am, edited 2 times in total.

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matsta
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Post by matsta » Tue Sep 04, 2007 12:15 am

awesome! looks completely real. great find.

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Post by BbB » Tue Sep 04, 2007 12:31 am

Yes, great. Though he looks a bit made-up to me. A little powdery, as though he'd just got out of a television studio...

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Stur
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Post by Stur » Tue Sep 04, 2007 12:37 am

Isn't the paper Ono used to build SSS Epidermis & Dermis stuff in Indigo ?

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CoolColJ
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Post by CoolColJ » Tue Sep 04, 2007 12:42 am

crazy, there are no bump maps, or textures used at all!!!!
it's just geometry from a 3d scanned head and 3 layers of SSS! :shock:

same with the leaf in the PDF, no textures....

eventually you could probbaly reduce everything down to SSS scattering and absorbtion levels, with displacement mapping for thickness and surface detail :twisted:
Last edited by CoolColJ on Tue Sep 04, 2007 1:48 am, edited 1 time in total.

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CoolColJ
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Post by CoolColJ » Tue Sep 04, 2007 12:52 am

Stur wrote:Isn't the paper Ono used to build SSS Epidermis & Dermis stuff in Indigo ?
probably not as there are no parameter values used like hemoglobin that can be found in Indigo, just basic absorbtion/scattering values etc

so technically speaking you could get the same result by creating the 3 layers with the right values. That's if Indigo renders the same way though :)

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CoolColJ
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Post by CoolColJ » Tue Sep 04, 2007 1:00 am

here is Ono's original post with paper link

http://www.indigorenderer.com/joomla/fo ... php?p=9880

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Stur
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Post by Stur » Tue Sep 04, 2007 1:07 am

Yep, he used another paper from the same site though. I've been misleaded by the model used in the paper.

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CoolColJ
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Post by CoolColJ » Tue Sep 04, 2007 1:11 am


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CoolColJ
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Post by CoolColJ » Tue Sep 04, 2007 1:30 am

the only thing is - why doesn't Indigo's Skin SSS system use virtual layers instead of having to physically model the separate layers?

That can get really expensive polycount wise with highly detailed models you find in humans and such!!!

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Kram1032
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Post by Kram1032 » Tue Sep 04, 2007 2:21 am

'cause it's tricky to code, I bet :)

...and it's hard to set them up, in some cases... in example, if you render a hand... completely different skin thickness - or do you have no bones in your fingers, which are 20cm thick? xD

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OnoSendai
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Post by OnoSendai » Tue Sep 04, 2007 2:41 am

You need to have a read of the Indigo Manual CoolColJ.
I've already implemented the dermis/epidermis stuff from that paper (or one of Jensen's other papers).
Someday I plan to implement the fast multi layer scattering approximation as well.

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Kram1032
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Post by Kram1032 » Tue Sep 04, 2007 2:50 am

uhm....
If *I* didn't miss anything, CoolColJ meant Virtual layers to implement :)
We all know, that Indigo has Epi-/Dermis :)

AND he talked about 3layered system, where Indigo has two layers....

Basically, the request was for virtual layers, though :)

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CoolColJ
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Post by CoolColJ » Tue Sep 04, 2007 2:56 am

I've already read the Indigo manual - a lot of times :)

but I wasn't talking about dermis/epidermis stuff though.

Virtual SSS layers so you don't have to model the actual layers, and then you can change layer depth/size at will with each having their own absorbtion/scattering, IOR values etc

maybe even have a UV map for each layer for depth/thickness.....

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Kram1032
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Post by Kram1032 » Tue Sep 04, 2007 2:59 am

Multiple UV maps per mesh, would be cool, in general :)

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