User Manual

The reason to use auxiliary data is that 3D rendering is computationally expensive and time
consuming, so outputting descriptive information about a 3D image that’s been rendered
empowers compositing artists to make sophisticated alterations in 2D. You can fine-tune focus,
perform relighting, and composite with depth information faster than re-rendering the 3D
source material over and over.
TIP: You can view any of a node’s channels in isolation using the Color control in the
viewer. Clicking the Color control switches between Color (RGB) and Alpha, but
clicking its pop-up menu control reveals a list of all channels within the currently
selected node, including red, green, blue, or auxiliary channels.
Fusion Node Connections Carry Multiple Channels
The connections that pass image data from one node to the next in Fusion’s Node Editor are
capable of carrying multiple channels of image data along a single line. That means that a
single connection may route RGB, or RGBA, or RGBAZ-Depth, or even just Z-Depth, depending
on how you’ve connected your node tree.
In the following example, each of the two MediaIn nodes outputs RGB data. However, the
DeltaKeyer adds an alpha channel to the foreground image that the Merge node can use to
create a two-layer composite.
MediaIn2 node connected to a DeltaKeyer node, connected to a Merge node, which is connected to another
MediaIn node to combine the two images using the alpha channel output by the DeltaKeyer.
NOTE: Node trees shown in this chapter may display MediaIn nodes found in
DaVinci Resolve’s Fusion page; however, Fusion Studio Loader nodes are
interchangeable unless otherwise noted.
Running multiple channels through single connection lines makes Fusion node trees simple to
read, but it also means you need to keep track of which nodes process which channels to make
sure that you’re directing the intended image data to the correct operations.
Node Inputs and Outputs
MediaIn nodes in the Fusion page and Loader nodes in Fusion Studio output all available
channels embedded in the source media on disk. When you connect one node’s output to
another node’s input, those channels are passed from the upstream node to the downstream
node, which then processes the image according to that node’s function. Only one node output
can be connected to a node input at a time. In this simple example, a MediaIn node’s output is
connected to the input of a Highlight node to create a sparkly highlight effect.
Chapter – 69 Understanding Image Channels 1385