Chapter 6: layers and properties, Creating layers, Layers overview – Adobe After Effects CS4 User Manual
Page 144: Layers and, Properties

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Last updated 12/21/2009
Chapter 6: Layers and properties
Creating layers
Layers overview
Layers are the elements that make up a composition. Without layers, a composition is only an empty frame. Use as
many layers as necessary to create your composition. Some compositions contain thousands of layers, whereas some
compositions contain only one layer.
Layers in After Effects are similar to tracks in Adobe Premiere Pro. The primary difference is that each After Effects
layer can have no more than one footage item as its source, whereas a Premiere Pro track typically contains multiple
clips. Layers in After Effects are also similar to layers in Photoshop, though the interface for working with layers differs.
Working with layers in the Timeline panel in After Effects is similar to working with layers in the Layers panel in
Photoshop.
You can create several kinds of layers:
•
Video and audio layers that are based on footage items that you import, such as still images, movies, and audio
tracks
•
Layers that you create within After Effects to perform special functions, such as cameras, lights, adjustment layers,
and null objects
•
Solid-color layers that are based on solid-color footage items that you create within After Effects
•
Synthetic layers that hold visual elements that you create within After Effects, such as shape layers and text layers
•
Precomposition layers, which use compositions as their source footage items
When you modify a layer, you do not affect its source footage item. You can use the same footage item as the source
for more than one layer and use the footage differently in each instance. (See “
Importing and interpreting footage
Changes made to one layer do not affect other layers, unless you specifically link the layers. For example, you can move,
rotate, and draw masks for one layer without disturbing any other layers in the composition.
After Effects automatically numbers all layers in a composition. By default, these numbers are visible in the Timeline
panel next to the layer name. The number corresponds to the position of that layer in the stacking order. When the
stacking order changes, After Effects changes all numbers accordingly. The layer stacking order affects rendering order
and therefore affects how the composition is rendered for previews and final output. (See “
Note: By default, new layers begin at the beginning of the composition duration. You can instead choose to have new
layers begin at the current time by deselecting the Create Layers At Composition Start Time preference (Edit >
Preferences > General (Windows) or After Effects
> Preferences > General (Mac OS)).
.
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