I am experimenting a bit with Specular materials to get a better understanding how they can be used for character renders.
My idea was to have a look at the RenderPasses to get a better understanding which settings to change.
Nevertheless at the moment I am stuck at the basics:
What exactly is the difference between Refraction and a SSS pass?
The way I understand it Refraction
is supposed to capture those light rays who are not reflected but actually enter a surface.
But would that not be the same as SSS
(Sub Surface Scattering)?
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Fiber mesh hair with Specular Material.
Character with mix material consisting of glossy and Specular Material.
The Specular Material has Transmission but no Absorbtion and Scattering values.Examples:
In this example you can see how the hair blocks the light from behind so no light rays are able to enter the back head surface.
Nevertheless a lot of rays are able to enter at the shoulder.
Hair: The hair has some refraction.
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There does not seem to be any SSS at all for the skin.Written in Hindsight:
Probably this explains why we should use a specular material with Transmission AND Scattering and not just Transmission when mixing materials.
Hair: The hair has some SSS.
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The first question I encountered was: `
What is the difference between a Refraction and a SSS pass??In hindsight after experimenting further I try to answer this myself:
If the rays pass trough you find the results in the Refraction pass?
If the rays get stuck somewhere in the geometry you find the result in the SSS pass?
Did I interpret the results properly or is there more to consider?
After all in the case of the fiber mesh hair there is a SSS AND a Refraction part!?! At the moment I find it very difficult to predict what the SSS, Refraction and Transmission passes will look like when I change the values of Transmission, Scattering and Absorption of a Specular Material.
- - -I tried to figure this out and experimented further. But the more I experimented the more questions started to raise.
My confusion increases when I look at the differences in the passes depending on if you use a Diffuse or Specular material.
If you take a Diffuse material with Transmission
As I would expect the transmission is output in the Transmission pass
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But when you create a Specular Material with Transmission
things seem to be different:
Now the Transmission is output in the Refraction Pass
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Now I add some Scattering to the previous Specular Material.A Specular Material with Transmission and Scattering
But now there is nothing to be found anymore in the Refraction Pass.
The result is now displayed in the SSS Pass
- - -Can anyone summarize some rules in which cases the values of Transmission, Scattering and Absorption are bound to be found in which pass when using Diffuse or Specular Materials?
Can anyone share some other examples of SSS, Refraction and also Transmission passes they created to get a better understanding how they could look if done correctly?