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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
When rendering CG you have the option to render in render passes. Render passes split up a render into different shading components. For example, you can render the diffused color separate from specular highlights, separate from a shadow, for instance. Now normally when you render in Maya, you get a beauty pass, and that's all the shading components combined, that's what you are used to seeing. But you do have the option to render as render passes, and these are great for compositing, it gives you a lot of flexibility because each component is on a different render, which you can affect separately. There are several ways to create render passes in Maya.
There is a simple way, which is through the Render layer Editor, and there is a more advanced way, where you go through mental ray and use the Contribution Map System. We are going to start with a Render layer Editor. Now we are not going to use the result of this for the final project, but this is very good to know, and I'll show you a quick way to create some very simple passes. I am going to start with where we left off on project 1, this is shot1_step3. We're going to have the spyglass and the lights set up, and it's basically ready to render in some form. So, how do you use a Render layer Editor? Well, it's in the channel box, so if you bring up the channel box, you'll see it's right beside the Display layer Editor, which you normally use to just hide or show objects in different layers.
So we click on the Render tab, there's the Render layer Editor. In this case you always get a master layer for free, and the master layer contains all of the objects in the scene, everything, all the services and lights. Now you can make a new layer at any point. What you can do is select an object, for example, I am going to select that spyglass. I'm going to go to the Hierarchy mode, I want to pick it as a Group, click on it, go over here to the Render layer Editor. I can use one of these shortcut buttons, in fact, the rightmost button is Create new layer and assign selected objects, so I can click that, and there is a new layer.
If I click on layer1, which is brand new, so it turns blue, we'll see that the spyglass is on that layer by itself. So it's similar to Display layer Editor, however, this is ultimately going to affect the way things render. Now if I render this at this point, the spyglass itself is going to be just pure black, because there are no lights. You have to consider what lights are on your layer also for rendering. What I can do though is go back to the master layer--and again, here is everything--and pick my lights. Now I am going to use a shortcut, I am going to go up to the Hypergraph, you can also use the Outliner.
I am going to select those lights by just selecting the nodes there just by drawing a marquee over it and go back to the Render layer Editor then, click layer1, so it's blue, right mouse-click and Add Selected Objects. So you can add objects to a layer at any point, and you'll see that the shading becomes bright again, it's not black, and then I could test render it. Now there is one thing you have to consider, and that's the Image Plane that I have attached to my perspective camera is still there. So I think I'm going to actually hide that, so it doesn't show up in the render.
So what I can do is go up to View here for the perspective camera, go to Image Plane > Image Plane Attributes, select that one Image Plane, that I had previously loaded--you'll see it right there in the sample--but then turn Alpha Gain to 0 and again that's the trick for hiding it from that view. Now if you do a test render, there's a spyglass by itself, and I'll shrink that render down so I can see it. So that's it. Now this is not very exciting because I have the spyglass and the lights, and there's not really anything else in the scene, but let's test the fact that you can have different objects on different layers, in this case. So I am going to hide this, and then create a brand-new piece of geometry.
For instance a Sphere, just so we have something in there we can see. I am going to scale it up and then go back to the Channel Box by clicking the Channel Box tab right here. Now if you go back to the master layer, it's on the master layer automatically. Now because it created on layer1 while that was selected, it's also on layer1. So it matters where you create it, what layer you're currently on. But what I can do now is delete that, so it goes away, go back to master layer, again, there's everything, then create it while I'm on master layer. So let's create a new Sphere, scale up so you can see it.
All right, that sphere again is on the master layer by default, everything goes there. But if I then go to layer1, it's not there. So you can create objects to always be on the master layer, but you can choose what layer they are on. Now I can add that sphere to that layer later, but if I never created on that layer in the first place, it's not there until I say Add Selected Objects. So master layer everything, layer1 just the things that I added and nothing else. So now I am ready to create some additional layers and then use the render pass options to create some actual render passes.