User Manual

Table Of Contents
Aux Channel
The Aux Channel menu selects the auxiliary channel to be copied from or written to depending
on the current mode. When the aux channel abcd has one valid component, it is copied as aaa1,
two valid components as ab01, three valid components as abc1, and four components as abcd.
For example, the Z-channel is copied as zzz1, texture coordinates as uv01, and normals
as nxnynz1.
Out Color Depth
Out Color Depth controls the color depth of the output image. Most aux channels contain float
values or, if they are integer valued, they can contain values beyond 255. When you copy float
values into an int8 or int16 image, this can be a problem since negative values and values over
1.0 can get clipped. In addition, precision can be lost. This option determines what happens if
the depth of RGBA channels of the input image is insufficient to contain the copied aux channel.
Be careful when copying float channels into integer image formats, as they can get clipped if
you do not set up Copy Aux correctly. For this node, all aux channels are considered to be
float32 except ObjectID or MaterialID, which are considered to be int16.
Match Aux Channel Depth: The bit depth of the RGBA channels of the output image
is increased to match the depth of the aux channel. Specifically, this means that the
RGBA channels of the output image are either int16 or float32. Be careful when using
this option because, for example, if you normally have int8 color channels, you are
now using 2x or 4x more memory for the color channels. Particularly, the Z, Coverage,
TextureCoordinate, Normal, Vector, BackVector, WorldPosition, and Disparity channels
are always output as float, and the Material/ObjectID channels are output as int16.
Match Source Color Depth: The bit depth of the RGBA channels of the output image
is the same as the input image. This can have some unexpected consequences. For
example, if your input image is int8, the XYZ components of normals that are floating-
point numbers in the [-1, 1] range are clipped to non-negative numbers [0, 1] range. As a
more extreme example, consider what happens to Z values. Z values are floating-point
numbers stored in the [-1e30, 0] range, and they all get truncated to the [0, 1] range,
which means your Z-channel is full of zeroes.
Force Float32: The bit depth of the RGBA channels of the output image is always
float32.
Channel Missing
Channel Missing determines what happens if a channel is not present. For example, this
determines what happens if you chose to copy Disparity to Color and your input image does not
have a Disparity aux channel.
Fail: The node fails and prints an error message to the console.
Use Default Value: This fills the RGBA channels with the default value of zero for
everything except Z, which is -1e30.
Kill Aux Channels
When this is checked, Copy Aux copies the requested channel to RGBA and then outputs a
resulting image that is purely RGBA with other channels being killed. This is useful if you want to
increase the number of frames of Copy Aux that can be cached for playback—for example, to
play back a long sequence of disparity. A handy tip is that you can use the Kill Aux feature also
with just Color to Aux > Color for a longer color playback.
Chapter – 85 Color Nodes 1882