Id matte effect – Adobe After Effects CS4 User Manual
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USING AFTER EFFECTS CS4
Effects and animation presets
Last updated 12/21/2009
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Preparing and importing 3D image files
ID Matte effect
Many 3D programs tag each element in a scene with a unique Object ID. The ID Matte effect uses this information to
create a matte that excludes everything in the scene except the element you want.
This effect works with 8-bpc, 16-bpc, and 32-bpc color.
Original (upper-left), with ID Matte applied using the near alien as the ID Selection (lower-left), and composited over a new background (lower-
right)
Aux. Channel
Isolate elements based on Object ID or Material ID.
ID Selection
The ID value for an object.
To determine the ID of an object, select the ID type from the Aux. Channel menu in the Effect Controls panel, and
click the object in the Composition panel or Layer panel using the Selection tool while the effect is selected. If Object
ID is selected for Aux. Channel, ID Selection automatically updates to the Object ID for the object you click.
Feather
The amount of feather along the edges of the matte.
Invert
Inverts the selection. Select to matte out the object specified by ID Selection. Deselect to matte out everything
but the object (default).
Use Coverage
Creates a cleaner matte by removing the colors stored behind the object from the pixels along the edge
of the matte. This option works only if the 3D image contains a coverage channel that stores information about the
colors behind objects.
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