The Duplicate and Duplicate
Special commands let you create either a complete duplicate
or a lightweight instance of the original. For example, you could
create armies and forests full of duplicate objects without needing
the memory or computing power to handle that much actual geometry.
An instance is like an
alias or shortcut or symbolic link in a file system: it’s a visual
pointer back to the original. However, each instance has its own
transform node so it can have its own position, rotation, and scaling.
An instance stays linked
to the original so when the original changes, the instance changes
too. If you move a control point on the original, all instances
automatically update. Instances do not have their own control points.
(In the Outliner an
instance appears to have its own shape node but this is actually
shared with the original.)
- Instanced lights have no effect.
- Some functions, such as extrude and insert,
cannot be used on instances.
- You can’t apply clusters and deformations
to instances, although you can of course use them on the original.
- There is always at least one non-instanced
transformation node between the instance nodes and the actual geometry
- You cannot create a hierarchy of instances.
If you create an instance of an instance node, Maya simply makes
a new sibling.
- File referencing connects objects by
name. If you replace a reference with a different file, instanced
objects within both files should have the same name. Otherwise you
may encounter errors when retrieving the scene.