extractDeltas is a plug-in for Maya which helps with the creation of corrective blend shapes to improve the overall deformation in conjunction with regular skinning.
It allows to model the corrective shape based on the deformed pose of a character and then generates a mesh which can be used as a blend shape target before the skin cluster calculation is performed.

extractDeltas is an important tool for creating corrective blend shapes but also requires some manual work.
If you are looking for a way to streamline your blend shape and corrective shape workflow check out SHAPES, a blend shape editor for Maya which combines a variety of tools for your everyday work.
SHAPES is free for private and evaluation purposes. Visit the SHAPES page.

 

Maya versions 2012, 2013, 2014, 2015, 2016, 2016.5, 2017, 2018 on OS X, Windows 64 bit, Linux 64 bit.

Please see the general install guide.

You can use the icons from the download to create shelf buttons for the commands.

Important:
The older version of the plug-in which is shown in the video came with two scripts. These are included in the current version and the commands are directly available when you load the plug-in.

extractDeltasDuplicateMesh
Duplicates the skinned mesh, deletes the intermediate object and unlocks all transformation attributes.

performExtractDeltas
Executes the extraction with the given selection. The command makes sure that the correct objects are selected. The skinned geometry must be selected first and the modeled corrective shape last.

If you are interested in using the actual extraction command from the plug-in in your own scripts you can use the following command:

extractDeltas -s <skinnedMeshName> -c <correctiveMeshName>

Please note, that in order to make the plugin work correctly you need a skinned mesh with a clean history. This means that it’s best if you only have your blend shape node followed by the skin cluster. If you have any additional nodes in the history or even deformers after the blend shape node the extraction process will most likely fail.
If you are looking for a more advanced correctives workflow take a look at SHAPES.

The original creator of extractDeltas is James Jacobs who once published it for a rigging/scripting workshop.

brave rabbit is responsible for maintaining the plug-in over the years and the conversion from a OSX only version to a multi-platform python plug-in. We also added some modifications to make the tool more reliable under various conditions.

Version 1.4, updated 2014-04-27