Vehicle rendering in Arnold: Car paint - Maya Tutorial

- [Instructor] Hi, I'm George Maestri and today I'm going to go a little bit deeper into vehicle rendering by creating a car paint material. Now car paint actually can be a very complex subject, because there's so many different types of different car paint, from metal flake to matte paint and so on, but I'm going to show you how to use Arnold's AI Standard material to create some of the more common car paint effects. So let's go ahead and get started. Now I already have the glass in this scene created, so let's just take a quick IPR render of our current scene. Now remember, we are using Arnold, so make sure your renderer is set to Arnold. So as we can see, we've got the glass already rendered, but the body of the car is still a lambert. So let's go ahead and create a basic material and then we'll apply that to the car. So I'm going to go ahead and pause my IPR and minimize it, and let's go into the Hypershade. So now that I'm in the Hypershade I can just right-click over this and we are going to create an Arnold material. So I'm going to go down to Arnold Shader Surface, AI Standard. And I'm going to go ahead and rename this CarPaint_Mat for material. So now I have a material and before we do anything with it let's go ahead and assign that material to the parts of the car that need it. So I'm going into my Outliner and I've organized this scene basically by material, so under BODY, I have a group here for the BODY, and that's all the parts of the car that are painted. So if I open this up all I have to do is Shift + select everything under here, right-click over it, Assign Existing Material, CarPaint material, and there we go. So let's go ahead and do a quick IPR of this and see what we've got. And as you can see, this is a basic material, but it has been applied. So before I do anything, actually I want to zoom in, 'cause I want to get a closer view of the highlights and the specularity on this car, so that way I can really fine tune this material. Now when you work with car paint you really want to focus on reflections and specularity and so on, so I'm actually going to go into this part of the car that has a lot of curves and this will give me a good guide as to how the specularity is working. So I'm going to do an IPR from this point and then we'll go ahead and start to work with materials. So now I have a little bit of a closer view and one of the things we can see about this matte material is it really is not showing the shape of the car, and that's one of the reasons why cars are painted kind of shiny, so you can see all of the curves and how they reflect in the light. So I'm just going to go ahead and select out part of the hood and this front fender and let's go ahead and just work with that area. So I want to make sure that I have part of the car selected that has that material on it, and I'm just going to hop over in my attribute editor to my CarPaint material. Now there's a lot of stuff that goes on with a car paint material, in fact, I'm going to go ahead and pause IPR, just so I can talk about this. Now there are a number of different things that we need to consider when we're doing car paint. Of course, we have a Diffuse Color, which is going to be our main color, but then we may also have things such as clear coats and second coats of paint, as well as undertones, as well as the specularity and the highlights and the reflectivity of this. So we're going to go through some of these controls and just show you how they affect the vehicle with respect to a car paint sort of scenario. So let's go ahead and start with Diffuse. So the first thing I'm going to do is just create a Color. Now this is an Aston Martin and typically they're silver, so I'm going to go against tradition and I'm going to do a darker color. And the main reason I'm doing this is just so that we have more contrast in the highlights, so we can kind of see this a little bit better. So I'm going to make the car kind of a dark blue, but not too saturated here. So I'm going to just kind of dial down the color, so it's kind of a darkish blue, somewhere around there. And so now let's go ahead and unpause IPR, so we can start to see this. Now with this dark blue you're still not going to see the curves of the car. That's really going to come from the specularity, so that's the next one that we're going to work with. Now Specularity is basically the highlights of the light. So the first thing I'm going to do is just go ahead and dial up the Weight of the specularity and as soon as I do that you can start to see how this immediately changes the look of this. Now if I turn this up really high you'll see that it's starting to get kind of this look of more metallic. It's not really looking like paint, it's looking more like metal. And that's not really what we want. So the real trick here is to not use the standard specularity. I'm going to turn on what's call Fresnel. And when I turn that on it adds in this additional control that allows me to control the specularity in a slightly different way. And as I turn it up you can start to see that this gives more of a paint-like effect. So it's a lot less metallic and the highlights are more isolated towards the curvier parts of the body of the car. So I can certainly turn down the Weight of the specularity, I can also work with Roughness. If I turn the Roughness down it will also get sharper. But even if I turn the Roughness down and turn off Fresnel you would still get kind of a metallic look to it, so Fresnel is really the key for getting a paint-like effect. So, again, we can dial this in as much as we want, but I'm going to go ahead and turn down the Weight just a little bit and keep some Roughness on there. Again, Roughness really just controls the sharpness of that highlight, so at 0 it's a completely liquid sort of effect and if you go up just a little bit above 0 you get an effect that looks a little bit more realistic. Now one of the things about car paint is that a lot of times they will put a tinted clear coat over the paint and that will give it kind of a two-tone effect, so when it reflects light it reflects in a different color. That's very easy to do with this particular material. All I have to do is just click on Color and change the color. So if I change it to a very different color, such as yellow, which is almost on the opposite side of the color spectrum, you'll see that we're getting this sort of effect. And this is probably not what we want, but if I were to turn this down and just add hints of yellow into that it might give a better effect, or I could just give a color that's slightly off from the original color, so maybe kind of a light blue or something like that. So if I create a slightly desaturated version of the original color then, again, it gives it the sense that it has a little bit more of a tinted clear coat. And you can play with this a lot, so I'm really just showing you some of the ways to create a better effect. Now in addition to this we also have what's called Sub-Surface Scattering. Now, again, you may have multiple coats of paint, so that we have one coat underneath that is showing through the other coats and they're different colors. Well, we can simulate that using Sub-Surface Scattering. So if I were to change the Color of this, maybe to like a cyan, and then I were to pump up the Weight to say something like .5 or so you'll see that this Sub-Surface Scattering is actually almost overwhelming the other color. So what we need to do is just bring this down into a very small amount. So I'm going to type in say .05 and what that does is it just gives a slight undertint to that car. And if it seen in different lights and different angles you'll start to get the effect. Now, finally, we also have Reflection and any sort of shiny car is going to reflect light. So what we need to do is go ahead and just turn up the Reflection as much as we want. Now, again, the more you turn it up the more mirror-like it becomes and maybe the less paint-like it becomes. Now paint does reflect, but it doesn't reflect that much. It's not really as mirror-like as you would like to think. So somewhere between .05 and .1 is probably a good value for this particular car. So now that I have this I'm going to go ahead and just back out just a little bit and frame the car and let's go ahead and do one more little render. And I'm still going to be using IPR for this. So let's go ahead and do a quick render and see what this looks like. So this is the final render and we can see the highlights very well and this is starting to show off the shape of the car. Now we can continue to work with this material, but hopefully we have an understanding of how all of the controls affect this particular material.