Selecting Region of Influence Types

There are four types of region of influence:

Zero: This creates no influence around the deformer.
Infinite: This is the default option. The influence goes all the way to the image boundaries or until it intersects with another zone of influence. When working on a cut-out puppet built on several element layers, the best choice is to keep the default Infinite option as the zone of influence type. In the following examples, the zones of influence are explained through deformation chains on a single bitmap image. It's also recommended to keep the regions of influence to Infinite when using Envelope deformers.
Elliptic: This creates a region of influence following the deformer. Its size is based on a radius value. When you set up the shape of your Elliptic zone of influence, you should be as accurate as possible and make sure that only the element you want to follow the deformation is included inside the zone.
Shaped: This creates a custom region of influence around the deformer that can be adjusted using control points and Bezier handles. When you set up the boundaries of your Shaped zone of influence, you should be as accurate as possible and make sure that only the elements that you want to follow the deformation are included inside the zone.
When you have an Elliptic zone of influence selected in the Node view, you can convert it to a Shaped zone using the Convert Elliptic Zone of Influence to Shape option.