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Bump and displacement mapping allow you to create surfaces that are not completely smooth. Let's go ahead and create a simple sphere. I'm going to go ahead and just put a Blinn shader on this. I'm going to go to my Rendering tab and just put Blinn material. Now if I scroll down here, you'll notice that there is a slot here for Bump Mapping. So I'm going to go ahead and just insert a 2D texture. Let's just go ahead and put that Cloth texture on there, and you really don't see it come up, but we have this Cloth texture attached to the Bump Map node, and so we can use this as a bump map, and we can also give it a Depth, so how bumpy is it? So let's take a quick render, see what that looks like.
You'll say oh yeah. That looks a lot more 3D, so it makes that Cloth texture look like it's deforming that surface. But there is a problem with bump mapping, and that is if we look at the edge of this sphere-- so I'm just going to zoom in kind of. What happens is is that it renders very smoothly, so this is really just a rendering trick. It doesn't actually deform the surface. It just shades the surface to make it look like it's kind of an irregular and bumpy, but it actually doesn't deform the surface itself.
So we can get actual deformation of the surface by using a deformation map, so I'm going to go ahead and apply another Blinn material, so we're actually going to kind of reset it, so now we have a simple sphere here, and we're going to add displacement map. But if we look here there is really no place to add a displacement map. Where we actually have to add this is in the master node. So if we go here to this tab, you'll see that we have kind of the container that contains that shader and down here we have what's called the Displacement material. Now displacement is applied as a material, not as a texture.
That's why we're doing it here. And so we can just apply this here, and then again we're just going to add in that cloth, and again, we don't see it until we actually render it. Now you can see exactly the difference. So we actually now very strong displacement. Now the one issue with this is that this surface here. If you're displacing outward, the actual surface is going to become bigger than what you see here. So, for example, let's go ahead and just put a simple plane underneath this and when I do that and actually render this, what you here is that this is actually poking through the floor.
So this is actually adding geometry that you do not see in the viewport. When you start using displacement maps like this, you kind of need to do test renders. A lot of times people will put displacement maps on ground planes to make them appear rocky or bumpy, and then when the character starts walking, his foot actually goes into the displacement, so you have to be kind of careful and just do test renders to make sure that everything is okay. So those are the differences between bump and displacement mapping. Now remember, bump mapping is really just a shading.
It doesn't really deform the actual geometry, and it's great for most situations, but those places we actually need to change the geometry, then you use a displacement map.
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