OTOY Forums

Hi,

Does anyone know of a tutorial on how to set up sub surface scattering?

I've looked at the manual but can't seem to make sense of the setup. For instance, with the scatter node how do I know what colours I should be picking for absorption and scattering etc.

Does anyone have any tips on how to set this up?

Thanks.

hi eric,

here's a description of the mediums (it's in the 3dsmax plugin manual, but should work in similar fashion as the lightwave plugin)
https://docs.otoy.com/3dsMax_2_X/?page_id=121

Here's some basic concept of SSS across Octane editions:

(1) create a specular material and add a scattering medium to it
(2) set the transmission (which controls the amount of light going though the object) to full (white) so you can clearly see how the light changes inside the object (3) adjust the scattering channel in the medium (this defines how fast light is scattered as it travels through the medium)
(4) set the absorption color (bear in mind that the resulting color will be the complementary color of the absorption color) And that's it.

In addition:
-you can adjust the phase channel to control the scattering direction (eg. will the absorbed light be scattered forward? or backward?)
-you can also add an emission texture in the medium (adds some fluorescent effect to the medium)

Super helpful, thanks so much for the info.

Using a specular material makes perfect sense for SSS. I think by using a diffuse material I was struggling to get the look I was after.

Great tip about the complimentary colours too!

All the best

This helps, but what would you use sss in a diffuse material for then?

using a diffuse material for sss does have some applications as this will work by enabling the transmission channel with a texture or an alpha image: you can imagine this being used if some patterns are desired.


On a previous note, just also want to add that the absorption works in a subtractive way. As you can see here, if the absorption color is exactly the same as the diffuse or transmission, this eats away at the diffuse or transmission:

So for something that is more diffuse than transparent (skin, wax candle, etc) are you better using diffuse, or specular, and what are the performance differences?