  We give a method for modeling solid objects undergoing large spatially
varying and/or anisotropic strains, and use it to reconstruct human anatomy
from medical images. Our novel shape deformation method uses plastic strains
and the Finite Element Method to successfully model shapes undergoing large
and/or anisotropic strains, specified by sparse point constraints on the
boundary of the object. We extensively compare our method to standard
second-order shape deformation methods, variational methods and surface-based
methods and demonstrate that our method avoids the spikiness, wiggliness and
other artefacts of previous methods. We demonstrate how to perform such shape
deformation both for attached and un-attached ("free flying") objects, using a
novel method to solve linear systems with singular matrices with a known
nullspace. While our method is applicable to general large-strain shape
deformation modeling, we use it to create personalized 3D triangle and
volumetric meshes of human organs, based on MRI or CT scans. Given a medically
accurate anatomy template of a generic individual, we optimize the geometry of
the organ to match the MRI or CT scan of a specific individual. Our examples
include human hand muscles, a liver, a hip bone, and a gluteus medius muscle
("hip abductor").
