- [Instructor] Welcome to Motion Graphics Weekly where you up your MoGraph knowledge one week at a time. I'm EJ Hassenfratz. Let's get our learn on. Cinema 4D R18 is the latest version of Cinema 4D with a lot of great new features. One I've been using a lot is the Inverse AO function, or Inverse Ambient Occlusion function that allows for super fast subsurface scattering type material effects. In this video I'm going to show you how I used it to create a waxy type of material.
So let me start by explaining what subsurface scattering is. It's the effect of seeing light rays passed through and illuminate objects like wax, jade, or even skin. Subsurface scattering is that light transmission effect that you see through thinner parts of those type of objects. The thinner the piece of geometry, the more light rays will penetrate and look like it's being illuminated from the inside. Subsurface scattering is also a very slowly calculating effect and this is where Inverse Ambient Occlusion comes in to help us speed things up.
Basically, ambient occlusion shading is a type of real life shading that happens when geometry is close to each other in block or occlude the ambient light, hence the name. Now I cover a bit of ambient occlusion in a previous MoGraph Weekly video where I use it to add a little bit of stylized grain to objects. So let's go ahead and here's my little wax composition with my wax letters in my basic texture. We have a creamy looking type of color here. We just have a little bit of reflectance going on, a little bit of reflection.
A bit of specular happening. And then just a little bump so it looks a little bit more organic. So what we're going to do is we're going to place our ambient occlusion in the Luminance channel. So I'm going to turn this on. Now this is typically where you would place the subsurface scattering effect as well. So you're going to see that this is just going to turn my whole composition white. And what I'm going to do is go ahead and load up my ambient occlusion shader. It's right here under the effects menu; Ambient Occlusion.
And I'm just going to click on this Ambient Occlusion button. So once I turned on that Ambient Occlusion, you can see shading in all the nooks and crannies of our text here. And that is due to the lack of ambient light reaching in those corners, in those folds of geometry. So Inverse AO is the opposite of that where instead of darkening the corners and calculating the light occlusion from outside of the object, it actually darkens from the inside out making thicker bits of geometry darker and thinner parts lighter.
So let's see this in practice. Let's go ahead and check on this Inverse Direction. So with the Invert Direction selected, we actually have our darker areas that were darker previously, now the brighter areas. Now for this subsurface scattering effect to work, we need to do one more thing and that is to reverse this gradient.
So we actually want the white chip on the left side and the dark chip on the right. So we'll go and invert these knots. And now we let this update and you can see exactly what happened. Now it looks like those thinner areas of our geometry are now being illuminated very brightly. We can also change this maximum ray length. So say that that light transmission is a little bit too wide. We can just bring down that width of the ray length and bring it down to, say, 35 centimeters.
It'll tamper down how bright that Invert AO is casting. So now you can definitely make out the thinner parts, or the edges, of our geometry are much, much lighter. So this is basically a fake subsurface scattering but doing it using a much faster method of calculating the effect. So we can go one step further and actually introduce some color into this gradient so it actually looks more like a waxy material and get rid of all these super dark areas.
So for the white, the lighter bits, we can make this a very light yellow or light cream. And then for the darker areas we can make this a darker brown or light brown kind of color. And let's see what that looks like. So that's actually super bright. So let's bring down the value. Make it a darker value of that orange.
So you can see how adjusting these gradient colors changes how bright that light transmission is. And also by changing how widespread that maximum ray length is, spreads out that illumination. So you can see how Inverse Ambient Occlusion is a great new feature in the new version of Cinema 4D R18 that allows you to create subsurface scattering effects, like this waxy texture, much quicker and much more efficiently.
Don't want to wait until next week to learn something new? No problem! Here are other ways to feed your creative brain to keep you busy in the meantime. You can check out my other courses in the library, visit my website, eyedesyn.com for more tutorials, subscribe to my YouTube channel to be alerted when I post a new video, join my Facebook page for daily MoGraph inspiration, and keep up to date on all my latest MoGraph creations on Instagram. Thanks for watching and I'll see you here again next week.
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