Fine-tune displacement and bump mapping.
- [Instructor] In the previous movie, we saw how to apply a displacement map to deform a surface to create a terrain. And here's a full-screen rendering of the result from the last movie, and as you can see, it's got some pretty serious artifacting that was not immediately evident in the small thumbnail rendering we did in the Arnold render view. So we need to address this issue, and I know that it's actually coming from the Arnold Auto Bump feature. Let's investigate. I've already got the hypershade open, and we're looking at the attributes for the displacement shader node, and the Arnold render view is open as well.
Auto Bump attempts to extract the high-frequency details that are lost when the mesh object detail is not high enough for the displacement map. So if we look in our view here, minimize the hypershade, we've got a pretty low level of detail landscape. These polygons are very large, and the level of detail here is not sufficient to resolve all the details in the height map, and so Arnold cleverly takes the high-frequency details that are lost and applies them as a bump map here.
And it often works quite well, but in this case it's not working terribly well because if we look very closely here, there's some polygon artifacting. I can get in closer there with the mouse wheel and move around with alt and middle mouse. These big squares here are coming from Auto Bump. So let's disable Auto Bump, and now it's cleaned up. We can go back to a one to one view, and it looks okay, but we've lost all of that detail that we had a moment ago. So we can just increase the detail by adjusting the shape node attributes.
So select the object in the viewport, and in its mesh shape node, in the Arnold section, scroll down, and you'll notice a subdivision section and a displacement attributes section. If you open Displacement Attributes, you'll see the same attributes that we saw in the displacement node, and these are here in case you're plugging a map directly into the shading group. If you're using a displacement node, then that's going to override these values here.
Okay, so those are not relevant right now, but subdivision is very relevant. Open that up, and what we want to do is make these polygons smaller. We just need to increase the level of detail. We don't need to actually smooth or average the angles between polygons. So we don't need a Catmull-Clark or OpenSubdiv implementation here. All we need is to set the type to linear and increase the iterations up, and as we do that, we'll start to see some details emerge.
Iteration's at two. We're getting more detail. We take it up to three. Now the subdivisions are able to fully resolve the detail within the EXR file, and there's no bump map applied to this material right now. This is just polygon geometry being deformed by the EXR file. We can finish this up by applying the bump map and the diffuse map from the proxy material. So back over to the hypershade now, I've got it minimized, and there's a bump map already attached to the other materials, so let's pan around with alt and middle mouse.
Here's bump2d. Bring that over closer to our AI standard surface, connect Out Normal from the bump2d node to the normal camera input on the AI standard surface. And in the Arnold render view, we can see we've got a bump map now. Let's also apply the diffuse map. Here's a file node, and it's currently labeled with the name of the file. Bring that down. Just make it closer, and connect its out color to the base color of the material, and now we've got a really nice rendering of a displacement map.
Let's admire out work, clean up the graph a little bit, drag a rectangle to select the AI standard surface and its shading group, and click Input and Output Connections, and here's our entire graph. So we can zoom in on that, or we can just click on Rearrange Graph. Back in the Arnold render view, we can make another snapshot and compare that to the proxy object. So here's the proxy object, and there's the Arnold displace mapped version.
That's how to apply displacement mapping in Arnold, and that concludes our chapter on materials and mapping.
- Arnold rendering concepts
- Lighting with Maya and Arnold lights
- Controlling exposure
- Filtering light with Gobo
- Light attenuation with Decay
- Image-based lighting with Skydome
- Exterior daylight with Physical Sky
- Arnold Standard Surface material attributes
- Mapping material attributes
- Rendering refractions
- Mesh subdivision and displacement at render time
- Shading effects such as ambient occlusion and vertex color
- Camera effects such as fisheye and depth of field
- Animation image sequence rendering