Skin - Iray - Scatter & Transmit?
(left and middle images only)
1st - Scatter only (Base color effect)
2nd - Scatter and Transmit (Base color effect)
I'm trying to figure out what it means. I mean, I can see the results are different and some people build their character skins with Scatter and Transmit, but I noticed when there's not enough light they look kinda gray... With more light however, it makes it look more realistic depending on the lights position... (the white in her eye, however, kinda pops out!)
Can someone please enlighten me?
Edit: I have found links that say the following:
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Base Color Effect - Setting the Translucency Weight to anything other than 0 opens the Base Color Effect options.
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Scatter Only - Diffuse is layered over Transmission and absorbs the remainder of any unused reflectance value.
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Scatter & Transmit - This works like Scatter Only, except with reflection, and based according to the Base Color's RGB; however, the remainder is sent to the Transmission layer instead of absorbed.
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Base color effect: Scatter Only = If you transmit you have second option for the SSS back reflectance
from http://snowsultan.deviantart.com/journal/MEC4D-Iray-skin-settings-537152092
Scatter Only Vs. Scatter And Transmit:
Several settings have this option now, including Base Color Effect, Glossy Color Effect, Metallic Flakes Color Effect and Top Coat Color Effect.
Looking at the DAZ docs, I think the key phrase is probably "layered over transmission" vs. "sent to the transmission layer." It sounds like Iray is applying a Scatter Only value on "top" of the transmitted color, which explains why setting a blue diffuse and a green translucency looks blue with Scatter Only and dark blue/green with Scatter And Transmit.
This explains why, in the DS Genesis 2 shaders, Base Color is set to Scatter Only (so that the skin's base color is strongly shown) but glossy is set to Scatter And Transmit (to better simulate wet stuff under the skin when using the specularity at its surface).
from http://sickleyield.deviantart.com/journal/Iray-Surfaces-And-What-They-Mean-519346747
But it's still very confusing. This transmission layer means SSS?


Comments
I did a small investiagtion by myself.
Please find some hints over here --> http://andysanderson.deviantart.com/gallery/58238151/Skin-Evaluations
I think the main difference is, that Scatter Only uses just the translucency whereas Scatter and Transmit also uses the SSS settings?