The Elastic Surface Layer Model for Animated Character Construction
Russell Turner, Daniel Thalmann
Proc. Computer Graphics International, 1993.
Keywords
Character Animation, Physically-Based Models, Deformation, Elasticity,
Articulated Figures.
Abstract
A model is described for creating three-dimensional animated
characters.
In this new type of layered construction technique, called the elastic
surface layer model, a simulated elastically deformable skin surface is
wrapped around a traditional kinematic articulated figure. Unlike
previous
layered models, the skin is free to slide along the underlying surface
layers constrained by reaction forces which push the surface out and
spring
forces which pull the surface in to the underlying layers. By tuning
the
parameters of the physically-based model, a variety of surface shapes
and
behaviors can be obtained such as more realistic-looking skin
deformation
at the joints, skin sliding over muscles, and dynamic effects such as
squash-and-stretch
and follow-through. Since the elastic model derives all of its input
forces
from the underlying articulated figure, the animator may specify all of
the physical properties of the character once, during the initial
character
design process, after which a complete animation sequence can be
created
using a traditional skeleton animation technique. A reasonably complex
character at low surface resolution can be simulated at interactive
speeds
so than an animator can both design the character and animate it in a
completely
interactive, direct-manipulation environment. Once a motion sequence
has
been specified, the entire simulation can be recalculated at a higher
surface
resolution for better visual results. An implementation on a Silicon
Graphics
Iris workstation is described.