Autodesk 62205-051408-9001 User Guide - Page 140

5 Compositing Combustion's fine control over layers gives you the ability to build "worlds within worlds" and to rearrange them dynamically in 2D or 3D space. About Compositing When you begin to build a composite, it can be helpful to think of a stage theatre as an analogy. You start with the backdrop, and then you add the scenery layer by layer, from back to front, until your scene is cohesive and complete. Compositing is literally the blending of multiple layers of footage, one on top of the other, into one convincing whole. Note: You can also use the Merge filter to quickly composite layers if you do not need to perform any transformations on them. Since the Merge filter does not contain lights or cameras, it has fewer calculations to perform than a composite branch. For information, see "Using Merge" in Chapter 9, "Working with Image Channels''. When you add a clip or image to a composite, it becomes the source for a new layer. Layers are 2D objects that you can arrange and animate in 3D space. If you choose 2D compositing mode, the layers are limited to 2D space. When you add a new layer to the workspace, it is placed on top of other layers in the composite (the stack). Layers at the bottom of the stack are covered by those above it. Compositing can simply consist of moving and resizing layers so you can place them together in a scene. Layers also have surface properties, which determine how the layer appears in the composite and how it reacts to light. For example, lighting will affect a layer with high glossiness and reflectivity very differently from one without, in much the same way that a shiny metal table differs from a rough, wooden one. These features are discussed in detail in Chapter 8, "Using Surface Properties''. When you do compositing, keep in mind that 2D composites have fewer options in the Composite Controls panel and Workspace panel than 3D composites. For a description of these options, see Comparing 3D and 2D Options. You use color channels and masks to create more complex, multilayered composites by using transparency to see through a layer to what is behind it. You can make a color or range of colors on a layer transparent, or draw a mask to isolate a specific area. These features are discussed in detail in Chapter 9, "Working with Image Channels'' and Chapter 10, "Using Masks''. You can use the Workspace panel, the Timeline, or the Schematic view to add layers and operators to a composite, copy layers between branches, and navigate between operator controls. Use the Workspace panel to reorder the layers. For information on the Schematic view, see Chapter 6, "Using Schematic View''. You can change a layer's position, rotation, or scale, and animate these changes over time. Use features like parenting and targeting to control how layers are affected by other layers. A layer can also contain a composite, which itself is made up of many layers. This is called nesting. Nested composite You add operators to a layer to modify it. For example, you can import a clip, color correct it, and 124