Hellboy, we needed to create full ranges of realistic (and sometimes very unrealistic) motion and deformations

A fast solving, semi-interactive, and physically-based deformation system was required that fit into an existing
animation pipeline.

To add photo realism to the hand animation, in both day, night, wet-and-dry environments for five CG characters in 15 sequences, 132 shots, Tippett Studio utilized a new, proprietary “muscle system and skin solver” developed by CG supervisor William Todd Stinson and character
set-up lead Paul G. Thuriot.

The muscle system stretches, contracts, and even adds tension, all to maintain a consistent volume of underlying anatomical geometry.

a layered system, simulating physical properties of muscle, fat, and sliding skin the skin stretches and slides in response to the motion of the character’s internal structure. interactive
enough to give the animators instant feedback for
pose deformations and to have a considerably
short, off-line solve time.

This was realized by two separate Maya plug-ins that could be used individually or in combination: tipMuscleBuilder
and tipSkinBuilder

For underlying structures, curve-based, NURBS
muscle surfaces are built by stating where the
surfaces attach to the underlying anatomy of a
creature in a relaxed pose. The muscle is then
shaped via attributes to fit the anatomical needs.
Volumetric attributes are turned on, storing the
base volume at a relaxed pose, and any
deformation to the underlying structure drives the
muscle. These deformations of muscles can be
viewed in real-time inside of the animator’s scene
file for instantaneous playback for posing
purposes

Muscle tension can also be simulated via artistic,
isometric contractions, prior to muscle
deformations, using animation information from
skeletal structures

Because of the plug-ins integration into Alias’
Maya software, any of Maya’s feature sets can be
applied such as soft-body dynamics, or particle
collisions for extra added jiggle.

The skin plug-in is applied to the rendered
surface(s) model. Using any collection of
NURBS objects as collision surface(s), the skin
plug-in finds and fills in the empty voids as a Fat
Layer between skin points and underlying
structures by multiple connection processes.
Numerous attribute values are then “painted” for
each skin vertex, stating what dynamic forces are
to be applied on and under the skins’ surface
during simulation.

Two skin solvers were finalized for the project.
The Dynamic Solver which adjusts skin vertices
by each point’s velocity, underlying masses, and
other specified forces. And the Static Solver
which relaxes skin points after first being moved
by the connected, underlying structure

Blair Clark

proprietary techniques based on naturalistic
anatomy for internal muscle surfaces

Developed a proprietary muscle
system and skin solver.