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ISUther

Creating a skinn shader using Houdini 16.5

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Hello,

I have following texture maps that are painted in Mari and saved out.

Base color Epidermal Color map - Outer layer of skin
Subdermal map - Deepest layer of skin
Mid scatter map - This is layer where i painted veins
Primary specular map - Dictates skinn general specularity
Secondary Specular map - Dictates where are the oili areas in the face (As you may know skinn is in some areas more oily then others)
Displacement map

Those are the maps i have at the moment painted in Mari for my orc.

And now trying to build shader for it in Houdini.

Basic skinn shader if i use that i dont know how tobring in my maps. As atm it has those color options that
dictates what color the skinn will be etc thus overriding my textures?
If i dive inside skinn shader  i have only 1 node
what nodes to use there in order to bring in my texture maps and how to connect those?

As i understand i can plugi in Base color Epidermal Color map to diffuse color
But where to connect all others.
And what node to use in order to bring those in?
If i clikc "tab" and select "Textures" options what i get are:
* Bump Texture
Displacement Texture
Normal texture
Texture
Vector Displacement Texture

Note! My orc model has UDIM texture maps.


Update:
If i use Skinn shader that is inside houdini
and i dive inside and create texture node (by pressing "tab"key >> selecting "Textures" >> Selecting "Texture" node)
And i load in my UDIM Textures for base color and i connect output named as "clr" to Skinn shader node Duffuse color i get an error:
https://youtu.be/qJJ9-PxvZcQ

and in addition here u can see my question also:

1.JPG

2.JPG

3.JPG

Edited by ISUther

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I found this post while looking for best Houdini - Mari workflow practices. I didn't see any responses so I'll try my best to respond but this might not be 100% correct.

First if using UDIMs make sure that you are using filename%(UDIM)d.ext. In the video at least when I went back to look at it you didn't have the %(UDIM)d but were using $F which unless it has changed in newer versions of Houdini won't work. Also don't forget in MAT context you need to bring in a uvcoords node, plug that into your texture node and then you can plug the texture into the shader.

To go over the "simple" Principled shader first you would want to have maps for 

A. A color map for the base(diffuse) color. This is the outer layer of the skin but light is not passing through.

B. A Color map for the Subsurface Color. The color that is under the skin or the meat.

C. A Scalar map that will drive the subsurface amount. Where the skin should allow more and less light. 

D. Specular(Roughness) and Displacment maps would work like they always have.

The Skin Shader is pretty much this same process but it allows up to three layers of skin shading instead of the one that is the subsurface color. So for each skin layer you want to use

A. A color map for the skin layer.

B. A Scalar map for the weight channel. 0 no subsurface color 1 all subsurface color.

Just because you have 3 skin color channels does not mean you have to use all 3. The skin shader will work fine with 1 or 2 skin layers and the ones you don't use the weight turned to 0. 

The advantage of the skin shader is that you have a scattering distance for each color channel.

 

I think for the veins you painted you would want some of them to appear on the base color, and some to appear as part of the subsurface layer but not as a separate scattering layer. Some veins are very close to the surface more appear as someone gets older and those would probably best be a part of the base color. Others are deeper so they don't easily appear on the surface. In Mari if you have the veins painted as a separate layer you could copy the veins into different channels and maybe mask or adjust the colors so that more or less appear across the body in the different render channels.

 

Some links on rendering skin.

http://gl.ict.usc.edu/Research/DigitalEmily2/ 

http://www.anderslanglands.com/alshaders/tut_skin1.html

https://www.fxguide.com/featured/pixar-deep-dive-on-sss-siggraph-preview/

Edited by Dentzz

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One tip:

Don't use spaces on your paths and in the file names.

Edited by Mzigaib

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You don't actually,

I am a strong defender of using mantra for everything in the matter in fact I already do when I can but this new sss is a huge obstacle if you want render characters, everything that we compared with sss in mantra unfortunately was much faster and cleaner, I am sure that Sidefx is already aware of this.

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