The redshift subsurface scattering we’ve been talking about is actually called single scattering. This is really good for refractive objects say things light-colored gloss colored liquids like wine or even like cloudy liquids.
Redshift also offers multi-subsurface scattering, when you’re dealing with materials like skin wax marble for example.
Select the Redshift material and open the node graph, you will see the Multi sss i,e the subsurface material that we looking for.
You will notice that the General parameter is set to zero, which means it only applies the diffuse and reflection layer on top.
If I bring the amount to “1”, now it’s 100% subsurface and there is no Diffuse, that’s not what we want, just show you the result.
You can also mix together to get a blend of those subsurface and Diffuse lighting by adjusting the amount in general parameters depending on your material setup
So this radius scale is actually kind of like control for how deep the light can go inside to the material before it gets completely scattered out.
I bring the radius to “1”, this is the kind of look you get.
It is worth mentioning that when you are dealing with photorealistic renders, you do want to stick to a real-world scale because if you’re trying to model something like the size of the table or model the car, the lighting and shaders will look different and you won’t get the kind of result you want. So it’s worth keeping that sort of thing in mind.
Also see: Best Guide on Cinema 4d Deformers
Testing with cube
Testing with the cube is kind of making easier what’s going on with subsurface Scattering.
So down below we got 3 Layers. The 1st layer is set to “1” and the other two below are set to “0”. The 1st one is the only one that’s actually contributing to this effect at the moment.
We can set the color here if you want to. The first thing you might notice is a kind of weird shadowing going on here almost like a kind of ambient occlusion sort of fact.
The reason for that is if we go up here to Include mode it’s only set to only sell so each object in the scene kind of calculates the SSS it’s like on its own.
Change the Include Mode to All Subject. You will notice that there is a big difference between in Subsurface Scattering
So you can say here if we change the radius scale to 5, the lights actually going further through the object. You might also notice that it’s kind of a bit strange how you’re getting a sort of yellow color in one area and blue in another.
Well, the reason for this is because as the light comes through it’s actually scattering to the color and because the lights getting scattered the rest of the light was left behind is actually a blue which is the complementary color.
So that’s kind of giving us all blue tint on the other side of this so it’s not being weird this is actually kind of physically-based way this would happen.
Here you see that I change the back radius scale to “1” in the General parameter
Each of these layers actually has any, not any weight and radius. and this radius is multiplied by what we have above the radius scale in the general parameter, so you can set this radius for example 10, and now it’s the same as before results. But it’s only affecting the layer as its own.
The good thing about this is that you can actually blend multiple layers together.
Mixing with Layers
So if I set the Layer 1 radius and weight to “1”.
Then I take the Layer 2 weight to “1” and Radius to “5”.Maybe I’ll set the color to be more blue something like the above.
There’s a bit of a funny effect, but you can see as the light travels through, The first couple of centimeters is yellow scattering then after that it’s going into this blue.
This is really good if you want to set up scenes like skin materials where the light changes color the further deep it goes into the material.
We’ve also got Layer 3 as well, you could set that weight to ‘1’ change that to another layer, color to red, and change the radius maybe around 30 to get this result. you can change as your requirement to get the beautiful Scattering!
You can sort of say the different layers of color going through as the light gets deeper.
Keep in Mind
So there are two more things I just wanted to talk about quickly:-
With these Values down, here they do auto normalize, and what I mean by that,
1.If you bring all the weight up to one, they kind of will add up to 1 as a whole number. So if all 3 layers are set to 1, each one is kind of contributing to 3rd layer.
if you take the 3rd layer weight down to 0 then the 2nd and 1st layer will add up to 1.
So whatever kind of combination you have for weight, it will always add up to 100 percent of your kind of subsurface scattering effect.
Last thing we talk about here,
The last thing to talk about here is Mode. By default, it’s set to Raytraced, and this is kind of the new method and most accurate. Anytime you are using the progressive mode, it’s always going to be raytraced.
We’ve also got the older called Point-based. And this is only active when you’re doing your final renders. But if you have set Bucket rendering what actually does is, calculates the subsurface scattering of pre-pass first.
Now, this is actually quite fast once it calculates this. You notice it just doing a quick Global Illumination(GI) calculation, quick subsurface calculation and it seems through renders all that.
When we set this back to raytraced, then it does the G.I then it straight into calculating the subsurface. This is a little bit slower but the raytraced method is also the more accurate
So, you have got 2 options depending on the scene.
I hope you have a basic understanding of how redshift subsurface scattering works, and how many types are. So, implement it in your scene and play around with the parameters to get the best output to your beautiful artwork!