Adobe 12040118 - After Effects Standard Tutorial page 377

Documentation for fnord ProEXR plug-ins is available in a PDF document on the
channel EXR file and an After Effects project that uses it. The instructions in the fnord document regarding the removal of the OpenEXR plug-ins
don't apply to After Effects CS5.
3D Channel Extract effect
The 3D Channel Extract effect makes auxiliary channels visible as either grayscale or multichannel color images. You can then use the resulting
layer as a control layer for other effects. For example, extract the depth information in a 3D channel image file and then use it as an influence map
in the Particle Playground effect, or extract values from the unclamped RGB channel to produce a matte that generates glowing highlights.
To display 3D channel values for a pixel in the Info panel, apply the 3D Channel Extract effect, choose the channel from the 3D Channel menu
in the Effect Controls panel, and then click the pixel in the Composition panel or Layer panel using the Selection tool.
This effect works with 8-bpc color.
Original (left), with 3D Channel Extract applied using Texture UV (right)
Much of the following information is based on information provided by Lutz Albrecht, who also provides a two-part document on the
website about integrating 3D applications with After Effects:
White Point, Black Point The value that is mapped to white or black.
3D Channel The channel to extract from the 3D image:
Z-Depth Represents the distance of a given shaded pixel from the camera. White represents the greatest distance; black pixels are
closest to the camera. Effects such as the Lens Blur effect can use this information to generate depth-of-field effects. When you apply the
channel directly as a luma matte, you get fog. This channel is anti-aliased.
Note: For best results, match the White Point and Black Point settings of the effect with the near and far settings of your camera in the
3D application that generated the 3D image.
Object ID Each object can be assigned a separate ID value in the 3D application. You can use a map generated using this channel to
selectively apply effects to certain objects in a 3D scene—for example, to apply selective color adjustments. This channel is not anti-
aliased.
Texture UV This channel contains the mapping coordinates of the textures of your object, mapped to the red and green channels. This
channel is not anti-aliased.
This channel can be used to check your UV maps or as input for the Displacement Map effect.
Surface Normals This channel maps the direction vector of each point on the surface of an object to the RGB channels. The vectors are
relative to the camera. Third-party plug-ins can use this channel as the basis for dynamic relighting and relief rendering. This channel is
anti-aliased.
Coverage The behavior for this channel varies for various 3D applications. It is used to mark areas near the edges and contours of
objects to provide information about their anti-aliasing and overlap behavior.
Background RGB This channel contains all RGB pixel values of the background without any foreground objects. It is mostly used to
store dynamic environmental effects unique to 3D programs such as skies or backgrounds generated from procedural textures. This
channel is anti-aliased.
Unclamped RGB This channel contains the colors from the 3D application as they were presented to the 3D application's renderer before
it applied exposure and gamma adjustments. This channel is anti-aliased.
Material ID Each material can be assigned a separate ID value in the 3D application. You can use a map generated using this channel to
selectively apply effects to certain materials in a 3D scene. This channel is not anti-aliased.
Depth Matte effect
The Depth Matte effect reads the depth information in a 3D image and slices the image anywhere along the z axis. For example, you can remove
a background in a 3D scene, or you can insert objects into a 3D scene.
To insert a layer into a 3D scene, apply the Depth Matte effect to the layer containing the 3D scene, set the Depth property to the depth at
which you want to insert the new layer, duplicate the 3D scene layer, select Invert for the 3D scene layer on top, and place the new layer
between the two 3D scene layers in the layer stacking order in the Timeline panel.
This effect works with 8-bpc, 16-bpc, and 32-bpc color.
fnord software website, which includes links to a sample multi-
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