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682 Chapter 20: Managing Scenes and Projects
Premultiplying saves computation time if you later
use this image in compositing. See
Premultiplied
Alpha (page 3–1091)
for more information.
Optional Channels group
For output RPF files, there are additional channels
that you can generate (and view in the rendered
frame window):
Z—Saves Z-Buffer information in repeating
gradients from white to black. The gradients
indicate relative depth of the object in the scene.
Mater ial Effects—Saves the Effects Channel used
by materials assigned to objects in the scene.
The Effects Channel is a material property set in
the Material Editor and used during Video Post
compositing. Each Effects Channel ID is displayed
using a different random color.
Object—Saves the G-Buffer Object Channel ID
assigned to objects u sing the Object Properties
dialog. The G-Buffer ID is used during Video Post
compositing. Each G-Buffer ID is displayed using
a different random color.
UV Coordina tes—Saves the range of UV mapping
coordinates as a color gradient. This channel
shows w here mapping seams might occur.
Note: UV Coordinates will not be displayed on
objects that have the UVW Map Modifier applied
unless a map has been applied that uses the
coordinates.
Normal—Saves the orientation of normal vectors
as a grayscale gradient. Light gray surfaces have
normalspointingtowardtheview. Darkgray
surfaces have normals pointing away from the
view.
Non ClampedColor—Saves areas in the image where
colors exceeded the valid color range and were
corrected. The areas appear as bright saturated
colors usually around specular highlig hts.
Coverage —Saves the coverage of the surface
fragment from which other G-buffer values
(Z Depth, Nor ma l, and so on) are obtained.
Z-Coverage values range from 0 to 255. To see Z
Coverage,rendertoanRLAfileafterfirstchecking
Z Coverage in the Setup subdialog, then choose
Z-Coverage in the rendered frame window’s
V iewing Channel drop-down list.
The Z -C overage feature is provided primar i ly for
developers, and should aid in the antialiasing of
Z-buffers.
Node Render ID—Saveseachobjectasasolidcolor
according to its G-Buffer Object channel (found
under Object Properties).
Co lor—Saves the color returned by the materia l
shader for the fragment. This channel displays any
transparentfragmentasasolidcolor.
Transparency—Saves transparency returned by the
material shader for the fragment. Any fragment
with any degree of transparency will be rendered
as a solid gray object.
Velocity—Saves the velocity vector of the fragment
relative to the screen in screen coordinates.
Sub-Pixel weight—Saves the sub-pixel wei ght of a
fragment. The channel contains the fractions of
the total pixel color contributed by the fragment.
The sum of all the fragments gives the final pixel
color. The weight for a given fragment takes into
account the coverage of the fragment and the
transparency of any fragments that are in front of
agivenfragment.
Sub-Pixel Mask —Saves the sub-pixel alpha mask.
Thischannelprovidesamaskof16bits(4x4)per
pixel, used in antialiased alpha compositing. This
mask is esp ecially useful with the Combustion
compositing product.
Descriptive Information group
This information is saved with the file.