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Matte Object Parameters
Opening the Matte disclosure control reveals the Is Matte option, which when turned on
enables two more options.
Matte parameters in the Shape3D node; enabling Is Matte reveals additional options.
Is Matte
Located in the Controls tab for the geometry, this is the main checkbox for matte objects. When
enabled, objects whose pixels fall behind the matte object’s pixels in Z do not get rendered.
Opaque Alpha
When the Is Matte checkbox is enabled, the Opaque Alpha checkbox is displayed. Enabling this
checkbox sets the alpha value of the matte object to 1. Otherwise the alpha, like the RGB,
will be 0.
Infinite Z
When the Is Matte checkbox is enabled, the Infinite Z checkbox is displayed. Enabling this
checkbox sets the value in the Z-channel to infinite. Otherwise, the mesh will contribute
normally to the Z-channel.
Matte objects cannot be selected in the viewer unless you right-click in the viewer and choose
3D Options > Show Matte Objects in the contextual menu. However, it’s always possible to
select the matte object by selecting its node in the node tree.
Material and Object IDs
Most nodes in Fusion that support effect masking can use Object ID and Material ID auxiliary
channels to generate a mask. The parameters used to accomplish this are found in the
Common Controls tab of each node.
Material ID parameters in a Shape3D node’s Inspector controls.
The Material ID is a value assigned to identify what material is used on an object. The Object ID
is roughly comparable to the Material ID, except it identifies objects and not materials.
Both the Object ID and Material ID are assigned automatically in numerical order, beginning
with 1. It is possible to set the IDs to the same value for multiple objects or materials even if they
are different. Override 3D offers an easy way to change the IDs for several objects. The
Renderer will write the assigned values into the frame buffers during rendering, when the
output channel options for these buffers are enabled. It is possible to use a value range from 0
to 65534. Empty pixels have an ID of 0, so although it is possible to assign a value of 0 manually
to an object or material, it is not advisable because a value of 0 tells Fusion to set an unused ID
when it renders.
Chapter – 76 3D Compositing Basics 1582