A soft mod deformer in Maya can be used for more than just modeling. Chris Lesage is a Character Rigging TD For MoonBot Studios in Shreveport, Louisiana. While working at a previous position with Ember Lab, Chris worked on a short film, “Majora’s Mask – Terrible Fate”. A character needed to have an animatable buying effect for his backpack to make it look like things were bouncing around inside.
Chris chose to use Soft Mods in Maya to facilitate this in the character’s rig. Why Soft Mods? According to Chris they have some interesting properties, because they are non-linear deformers. As such you can move the deformer through the geometry or the geometry through the deformer. This premise can lead to some interesting bulging, sliding and bending effects.
Lesage offers a great little writeup on how to set up this simple, clever and easy soft mod rig in Maya. He also offers a scene file for download and study.