Creating rough or bumpy surfaces
Video: Creating rough or bumpy surfacesNearly everything that you probably can see right now has some sort of texture on it. Even something as simple as a mirror, at the finest level, it has bumps. In CINEMA 4D, the programmers have given us the ability to make rough surfaces. In fact, they've divided that into two different techniques. One is called the Bump channel and the other is called displacement. The Bump channel simulates indentations on the surface of an object, and the Displacement channel actually creates indentations on the surface of an object. Let's see what that means.
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CINEMA 4D Essentials with Rob Garrott is a graduated introduction to this complex 3D modeling, rendering, and animation program, which breaks down into installments that can be completed within 2 hours. This course shows how to lend 3D objects color, transparency, and life with materials, textures, and lights. Author Rob Garrott explains how to create a variety of surface textures, from smooth and reflective to bumpy and flat, and how to add dramatic depth and shadows to your scenes with the different light types in CINEMA 4D. The final chapter discusses texturing in 3D with the BodyPaint module, which can also help hide UV seams.
- Understanding material channels
- Applying materials via projection
- Limiting materials with selection tags
- Texturing type
- Using Falloff to limit the effects of lights
- Working with visible or volumetric light
- Painting on objects and textures with brushes in BodyPaint
- Hiding seams with projection painting
Creating rough or bumpy surfaces
Nearly everything that you probably can see right now has some sort of texture on it. Even something as simple as a mirror, at the finest level, it has bumps. In CINEMA 4D, the programmers have given us the ability to make rough surfaces. In fact, they've divided that into two different techniques. One is called the Bump channel and the other is called displacement. The Bump channel simulates indentations on the surface of an object, and the Displacement channel actually creates indentations on the surface of an object. Let's see what that means.
I've got a very simple scene that I'm starting with here. I'm going to make a new material by double-clicking in the Material Manager. In this material I'm going to go to the Basic properties and I'm going to activate Bump. Nothing happened. The reason that nothing happened is that the Bump channel needs information in order to generate bumps, and what it needs is a grayscale map. You can put a color image in there, but it's only ever going to need to look at the light and dark values. Now I've created a special texture that's got a good illustration of how this property works.
So I'm going to go to the Bump channel and click on that load image button, and in my texture folder I'm going to navigate to the Bump-Displacement.psd. This is a simple Photoshop file. It's got 50% gray, with a white type and a black type. The reason I've done that is because of the way that the Bump channel works, and the same is true for the Displacement channel. 50% gray does not move. White goes up and black goes down. So this image gives us the perfect illustration of those three states.
So I'm going to hit Open. It looks like nothing's happened here on our projection sphere, but I don't want to start off by applying it to this plane. So when I take the material and drag it onto the plane object, I can now see an indentation there. You can see a preview of that here in the Editor window, but if I hit Command+R or Ctrl+R on the keyboard, I can now see a better representation. It's a little bit hard to see at the angle that we have, so let's go back to the material and crank up strength of the bump. And I'll really crank that up, and let's zoom in on this and then hit Command+R or Ctrl+R on that keyboard.
Now you can see that we've got that. The white is going up, the black is going down, and the 50% gray hasn't moved. You'll notice that's a little bit chunky on the edges of this, and that's because of the anti-aliasing, but it's also because the Bump channel is just simulating those indentations. The best example of that simulation I can show you is on the cube that we have here in the scene. Let's go over here to the cube and take a look at that. I'm going to make a new material. Let's call it cube.
In that cube material, I'll go to the Basic properties and activate Bump again, but this time instead of the image, let's load in Noise. So I'll add noise to the scene, and you can see that I've now got this wrinkly kind of sphere here. Let's apply this material to the cube and then let's do a rendering. Command+R or Ctrl+R. It looks like my cube is a little bit bumpy, until you see the edges. If you look at the edge here, the edge is completely straight, and that's where the simulation breaks down. Let's apply that same material to the sphere.
I'll make a copy of the cube material by holding down the Ctrl key and dragging to the right. Let's rename this sphere. Let's take that material and apply it to the sphere and let's render. Command+R or Ctrl+R. And you'll see that we have the same issue on the sphere. At the outer edges that sphere is completely smooth. Bump simulates surface indentations. Now let's take a look at displacement, which is the counterpart to bump. Displacement actually creates surface indentations. So let's go back to our plane object.
Let's navigate over so we can see that, and I'll dolly out a bit. And now on the original material that we have applied to our plane, which is this one in the middle here-- in fact, let's name it and call it plane. In that one, let's disable the Bump channel and activate the Displacement channel. So we'll go to the Basic properties and disable the Bump and then we'll turn on Displacement, which is right here. Now in the Displacement channel we need the same sort of information. There's quite a few more options here for the displacement, but we still need to load in an image.
Now we could use the noise pattern before, but let's load in that Photoshop file. So let's navigate out to the Finder and go Bump and Displacement and hit Open. You can see that our previous sphere looks quite a bit different, but it doesn't really look like anything's changed on our plane. Let's render that. Command+R or Ctrl+R. You can see that we've got some bumps showing up on this surface. One of the things to remember about displacement is that it's resolution-dependent. It's dependent on two resolutions: the resolution of the object--how many polygons it's made up of--and the resolution of the material--how many pixels it's made of.
When you're using a procedural shader like Noise, it is mathematically generated, so it has no pixel values, and so you can zoom in on it or blow it up to any size and it's always going to render great. Photoshop files, on the other hand, are resolution-dependent. They're pixel-based, so you have to be very careful. There's only so far that you can push those. In order for me to get this displacement map to show up so I can read the white up here and the black down here, I have to increase the resolution of the plane. Let's go to the plane object and on its Object Properties, let's change the Width and Height segments.
Let's start of by making them 100 x 100, and let's hit Command+R or Ctrl+R in the keyboard. Now you can see it starts to give us enough resolution. It's a little bit chunky in areas, but it's actually indenting and extruding that type. Let's actually look at it from the side as well. I'll look at it from this angle. Let's kind of go to edge on and hit Command+R or Ctrl+R. You can see there it is going down; there it is going up. Let's orbit back around over here, and let's crank up the Width and Height segments to, say, 300 x 300, and now let's hit Command+R or Ctrl+R.
You can see I have a much better representation. Now we're getting into the range where we're seeing the limitations of the Photoshop document that we're using as this material. We can actually see the pixels that make up that in the object. It can be very problematic when you add additional polygons to your models. Polygons are very heavy to drag around in the Editor view. Because of that, the programmers have given us an additional tool for displacement called Sub-Polygon Displacement. Sub-Polygon Displacement allows you to have a really clean displacement on your object without having to add so many polygons to the surface.
So let's take our plane and make the width segments back down to 20 x 20, which was the default, and hit Command+R or Ctrl+R. You can see we're back to vague lumpiness. Now we can go back to our plane material and in the Displacement channel, we can activate Sub-Polygon Displacement. Now what we're getting is a subdivision level of 4. That's the default. When we render--Command+R or Ctrl+R--you could see that we're back to where we were when we had cranked up the resolution on the plane itself. Round geometry can be very useful when you're working on certain types of organic shapes.
In the case of this plane, it's not going to do very much, so I'll just turn it off again. Something to keep in mind when working with Sub-Polygon Displacement is that the subdivision level does affect your render time, so you have to be very careful with cranking that up. The more dense your object is to start with, the fewer subdivision levels you should need in order to get a good clean displacement. One last thing to talk about with displacement in general is on spheres. Let's move over to the sphere object and take a look at the material that we have applied to the sphere.
I'll leave the Bump channel turned on and then go to the Basic properties and activate Displacement. Let's go into the Displacement channel and then let's load in the Noise. We've got the exact same Noise values in the Bump and the Displacement. Let's render it and see what happens, Command+R. It looks like nothing. The reason that nothing happened is because of a very important property of the sphere object that's different than all the other parametric objects. If I select the sphere, the sphere has something called Render Perfect under its Object properties.
That forces the sphere to render the same way no matter what the segments are. If I change these segments down to 3, here in the Editor window it looks like a diamond or something like that, but when I render-- Command+R or Ctrl+R--it still renders as a sphere. Let's undo that and get back to the default 24 segments. When we uncheck Render Perfect, now the sphere can be affected by the displacement map. Let's hit that Command+R or Ctrl+R. You can see that it's starting to lump out those guys. Let's go to the sphere and turn on the Sub-Polygon Displacement now and then hit Command+R or Ctrl+R.
Now we start to see a truly lumpy sphere. Now that you understand the components of rough or bumpy surfaces, there's probably some great examples around your office. A good way to practice is to pick something and try to recreate it right there in the software.
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