Join Donovan Keith for an in-depth discussion in this video Creating a rusted metal material with the Layers shader, part of Creating Materials in CINEMA 4D.
In this video we're going to take a basic skill material and ravage it with rust. This is a reference image a general starting point for what it is we're trying to create. And we see that we have steel and we have rust there, two main materials that play here. The steel is shiny. It's reflective. It's reasonably smooth. The specularity, that's going to be fairly high, and the rust itself is fairly matte. It's not very specular. The color is roughly red. And in terms of bumpiness, there's a very fine bumpiness to it, sort of, along the surface.
And the main bump especially in this first piece of reference is in the interplay between the steel and the area that's rusted away. Now, as we take a look at our Rust Alpha, this Rust Alpha image is, is seamless texture that I've created from that Rusty Steel Reference. I've selected for the RustyElements and used those to build up this AlphaChannel. Now, I've created a scene for us that has a default rust material. It's basically a red, and maybe dark gray material. And in terms of bump, there's not a lot going on there.
We've also go a steel material, which is reflective and it's sitting over the top of our rust surface on our teapot. When we render all we really see is this smooth steel and so what I'd like to go over now is how to start eating away that steel. Go ahead and open up the old steel material and go to the Alpha channel. It should already be turned on. Next, to texture here there is three dots go ahead and click on those and go to your texture folder and locate the rust_alpha.png file then go ahead and choose open.
What you'll notice when you turn on the interactive render region is that you will have rust showing through but I think I might want a little more steel than I am seeing at the moment. Also my interactive render region is pretty slow so I am going to go into my render settings and temporarily turn off global illumination. If you have Cinema 40 Prime this probably won't even be an issue. So, now I've got a faster preview and I can use this to start playing around with my texture. I'm going to add a filter shader to my rust alpha so that I can control how much rust there is. Go ahead and add that filter shader and then click on it. If you turn on clipping, you can adjust high clip to ensure that there are more regions of steel.
And you can bring up the low clip to ensure that there are more regions that are totally rusted. And so now we've got a strong interplay between the steel and the rust. I'm now going to use this to feed the bump channels for both of my textures. So, I'm going to take my Alpha here, and I'm going to copy it. So, take the alpha channel, click on the triangle next to it, and choose Copy Channel. And for your steel, click on Bump, because my steel is my top texture, I want it to appear to raise up. So, I'm going to click on this triangle next to Texture, and choose Paste Channel. The steel is now rising up from the surface, and looking pretty good. But my rust appears perfectly flat.
I want to give it a little bit of depth as well. So, now I'm going to go to my rust material, go to its bump channel and load in a texture as well. And for this, I'm just going to load in my plain rust alpha. This way, I can get a lot of variation within my texture. And if I want, I can play around with the string. This is it at plus 100. Let's see what it looks like at negative 100. I can't really make this out from this distance, so I'm going to zoom in just a little bit on a region. Let's go ahead and leave the bump strength at maybe around 50%, and add a filter shader to add a little bit more contrast.
So, click on the triangle next to Texture and choose Filter. Go ahead and click on that filter shader. And, let's just increase the contrast overall. It's going to make our bump a little bit more extreme, and I'd say that we're off to a pretty good start now. I'm just going to hit Cmd+Shift+Z to undo my movement to my camera. And take a look at my render. This is looking pretty good, I feel though, that I'm going to want to selectively darken parts of my rust, and I'm going to do that by adding that same material to my diffusion channel. So, double click on rust, and activate the diffusion channel. And inside of there click on the three dots and locate that rust alpha image. You'll see that this is now darkening up that portion of our image. If I just lower the mix strength here, I'm getting a good combination of all of that. Let's just go ahead and do a final preview render.
Oddly steel looks more like steel when it rusted. And that's because of striking difference in color, specularity and bump between those two surfaces. Layering a materials and creatively using the same map over and over again allows it to combine these different elements seamlessly.
- Applying materials to objects, NURBs caps, and polygon selections
- Creating glass using transparency and refraction
- Building colorful backgrounds
- Creating plastic, metal, and concrete
- Mapping an image to a video screen
- Adjusting material placement
- Creating layered materials with photographs and the Filter shader