Adobe After Effects - Manual (Page 460)

Fog End Depth
Scattering Density
Foggy Background
Gradient Layer
Layer Contribution
To the top
Aux. Channel
ID Selection
Feather
Invert
Use Coverage
To determine the depth of an object, click it in the Composition panel or Layer panel using the Selection tool while the effect is selected.
Where along the z axis the diffusion reaches its maximum.
Determines how quickly the scattering occurs. The higher the value, the more dense the fog appears from its starting point.
Creates a foggy background (default). Deselect to create transparency at the back of the 3D scene for compositing on top of
another layer.
(Optional) A grayscale layer to use as a control layer, the luminance values of which apply to fog density. For example, use the
Turbulent Noise effect to create a swirling control layer for atmospheric fog. Make sure that the dimensions of the gradient layer are at least as
great as the dimensions of the 3D scene layer.
How much the gradient layer affects the fog density.
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)
Isolate elements based on Object ID or Material ID.
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.
The amount of feather along the edges of the matte.
Inverts the selection. Select to matte out the object specified by ID Selection. Deselect to matte out everything but the object (default).
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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