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- Working with image sequences
- Matching the 3D camera to video footage
- Lighting models in Maya
- Splitting a scene into multiple render passes
- Batch rendering
- Recombining render passes in an After Effects composition
- Setting up motion trackers
- Refining layers with rotoscoping
- Adding blur and effects
- Adjusting shadows and matte edges
- Using color correction
- Stabilizing shaky video
Skill Level Intermediate
Once you start using the Render layer Editor in creating custom layers, you can do a lot with just the render pass options to create render passes. However, there are a limited number of options there in terms of Diffuse, Shadow, Specular, and so on. You can create more complex render passes if you use some Material Overrides. Material Overrides is the option to the Render layer Editor to assign material to entire layer temporarily. Beyond that you can also use Render Overrides. Render Overrides give you the option to render out a particular layer with very specific render settings that are unique to that layer. So let's give that a try.
So I have gone back to shot 1_layers2 and here we have our three custom layers, and they are all set to different render passes, one's Diffuse, one's Specular, and one's Shadow. In this case, Specular is on the top, Shadow is in the center, and Diffuse is on the bottom above the master layer. All of those layers are turned on the render. Now we can create a brand-new layer and assign a custom Material Override. So what I will do is I am going to copy just this monolayer here, the Diffuse layer, right mouse key, Copy layer. There is a brand-new layer. I am going to turn off all my layers in terms of rendering except for that new layer.
For the Material Override, I can right mouse key, and there is an Overrides menu. If I go further, there is Create New Material Override, and then you get a long list of all the materials inside Maya. The first few are Maya materials, and you have a long list of mental ray materials. You can pick anyone's of those materials. For example, if we want to create a special layer that renders all the mattes --and matte being a solid black and white renderer you can use in compositing to cut something out--what I can do is go up to Surface Shader and select that. Once I select that material, that material is assigned to everything on that layer.
In fact, the color changes instantaneously. Now it's pure black right now, but if I change the color of the surface shader, we will be able to see it. So I am going to go to the Hypershade, and that material I assign is the last one on the list. So I can double-click that, open its attribute editor, and then change its color. Now the surface shader of the color is set by the Out Color. So I can change that to White, and that's more useful in this case. Then close the Hypershade and do a test render. I am going to go back to the Channel Box though, because I want to double-check my options on my render layer.
I am going to go to Options > Render All layers, look at the option box. Right now, I am set to Composite and keep layers. Now I only have one layer that's going to render here. So I can actually just go to composite layers. That's fine. Hit Apply, and then hit Close. So I am going to render out this window here, and there it is. This is your custom matte pass. What you have is a solid white object over a black field, and that's all in RGB. You can use that in the composite later on to cut something out, and actually for this particular project, this becomes very useful. So when it comes to assigning Material Overrides, you can pick any material that you might find useful, again, to assign to all of the surfaces on that layer, it's only temporary--or I should say it's nonpermanent--because if I go down to the master layer, all original materials are still there and unaffected.
I also mentioned it's possible to create custom render passes by altering the render settings for a particular layer. There is a different way of doing that. For example, if I turn off this layer and go back down to my original monolayer, turn that back on, what I do is click this third icon button, which is a Render Settings Override button, and click that. That actually brings up the Render Settings window. However, in a special layer mode. In fact, you can tell that by going up here and looking at the title bar. It says Render Settings (monolayer). That means that these are the render settings just for this layer.
You can create an override for any of the attributes that appear here. So for example, I can switch the Render Using to a different rendering engine just for this layer. How do you do that? Well, you right mouse key over an attribute name, like this, Render Using right mouse key, and choose Create layer Override. As soon as you choose that option, that particular name turns orange. Once it's orange, I can pick a different option like mental ray. It switches to mental ray. That means that just this layer is using mental ray, because this is an override.
Now to remove that override you can right mouse key again over the name and remove it, but as long as it's orange that's a unique override for that layer. Every layer can have a different set of overrides. You simply click one of these buttons right here with a little clapboard and then choose an attribute right mouse key and then Create the Override. So now if I was to render out all these various layers, even if they are all on, only this one is going to use mental ray. The other ones use Maya software by default, because we go back to the master layer, the master layer has a default setting. So any layer that does not have an override uses the master layer as reference.
In fact, the master layer has a tab for every single rendering engine on it. So it serves as the master. Note that using the Render layer Editor to create render passes and to use Material Overrides and/or Render Settings is just one solution for breaking up the render into different passes where you have different shading components. We also have the mental ray contribution map system, which we are going to talk about in the next chapter. So using the Render layer Editor is really just for your knowledge. It's very good to know that, understand how it works. We are going to use a mental ray system for project 1 and project 2.