A script and deformer that can invert a shape through a deformation chain so the shape can be applied as a front of chain shape. This has the same functionality as Christian Breitling’s correctiveShape plug-in. He stopped providing it after Maya 2008 so I’m providing a Python version that doesn’t need to be compiled.

cvshapeinverter is a Maya module that can be installed like all other Maya modules. You can do one of the following:

• Add the cvshapeinverter root directory to the MAYA_MODULE_PATH environment variable.
• Add the cvshapeinverter root directory to the MAYA_MODULE_PATH in your Maya.env. e.g. MAYA_MODULE_PATH += /path/to/cvshapeinverter
• Edit the cvshapeinverter.mod file, and replace the ./ with the full path to the cmt root directory, then copy the cmt.mod file to where your modules are loaded from.

Pose your skinned model in the pose that you want to correct. Duplicate the mesh and sculpt in your fixes. Select the original skinned model, shift select the corrected model and run:

import cvshapeinverter
cvshapeinverter.invert()

# or without selection
inverted_mesh = cvshapeinverter.invert(base_deformed_mesh, corrective_sculpt)

An inverted shape will be generated which you can then apply as a front of chain blendShape target. The generated shape will have a live deformer affecting it so edits you make on your corrected mesh will be inverted through the deformer.

The mesh should not have any absolute deformations in the deformation chain. This includes blendShapes that still have the targets connected.