With this method of shape animation, you create multiple target objects that are duplicates of the base object, then modify the vertex positions on each one of the target objects into the forms you want. For example, you can use this method for facial animation, with each target object representing a different facial expression.
This method of shape animation creates more geometry in the scene, but it's easy to return to the target object for modifying. Having target objects also lets you take their geometry into sculpting programs, such as Autodesk Mudbox, to do further editing and then import them back into Maya. As well, you can use deformers such as lattices to deform a target object. See below for tips on dealing with target object geometry.
You can also blend a hierarchy or group of target objects on a hierarchy or group of base objects. Make sure that both hierarchies have the same number of children and parenting relationships. Each child in the target object hierarchy blends with its corresponding child in the base hierarchy. The order of children in the Outliner (or Hypergraph) determines which children blend, so you can change the order of the children by middle-dragging them in the Outliner so that the hierarchies match.
To create blend shapes using multiple target objects
For more predictable deformation results, it's best to not change the number of vertices, faces, or edges on the base object after you have created the blend shape deformer. They should match those of the target objects. However, if you do, you can propagate those changes to the target objects - see Propagate topological changes from base object to target objects. This deletes the Input history on an object.
When you create the target objects, don't freeze their transformation after you have moved them. They need to have the same transform values as the base object. It's better to create the target objects where the base object is (the scene origin is best), freeze their transforms (choose
from the main menu), and then move them to where you want them.If you're blending hierarchies or groups, select the parent (its transform node) of the target object hierarchy or group first, then add the parent of the base object hierarchy or group to the selection last.
If you want to delete the target objects automatically when you create the blend shape deformer, see Delete target objects.
Having geometry for target objects can make your scene larger, but here are some ways of optimizing that: