Indirect skinning methods include lattice skinning and wrap skinning.
In lattice skinning, you skin the influence lattices of lattice deformers. These influence lattices in turn influence other deformable objects (for example, NURBS surfaces or polygonal meshes). An advantage of lattice skinning is that you can easily make adjustments to the deformation by tweaking influence lattice points.
For more information about lattice deformers, see What are lattice deformers? in the Deformers guide.
In wrap skinning, you skin the wrap influence objects of wrap deformers. These wrap influence objects in turn influence other deformable objects. An advantage of wrap skinning is that you can skin low-res objects and use them as the character’s low-res model, then later introduce the high-res model and deform its objects with the low-res objects.
For more information about wrap deformers, see What are wrap deformers? in the Deformers guide.
