Skeletons are at the core of 3D character animation. The goal of this
work is to design a morphable model of 3D skeleton for four footed
animals, controlled by a few intuitive parameters. This model enables
th automatic generation of an animation skeleton, ready for
character rigging, from a few simple measurements performed on the mesh
of the quadruped to animate.
Quadruped animals - usually mammals - share similar anatomical
structures, but only a skilled animator can easily translate them into
a simple skeleton convenient for animation. Our approach for
constructing the morphable model thus builds on the statistical
learning of reference skeletons designed by an expert animator. This
raises the problems of coping with data that includes both translations
and rotations, and of avoiding the accumulation of errors due to its
hierarchical structure. Our solution relies on a quaternion
representation for rotations and the use of a global frame for
expressing the skeleton data. We then explore the dimensionality of the
space of quadruped skeletons, which yields the extraction of three
intuitive parameters for the morphable model, easily measurable on any
3D mesh of a quadruped. We evaluate our method by comparing the
predicted skeletons with user-defined ones on one animal example that
was not included into the learning database. We finally demonstrate the
usability of the morphable skeleton model for animation.
Character Animation, Character rigging, 3D Animal Modeling, Intuitive
Interfaces for Animation.
Reveret, L., Favreau, L., Depraz, C., Cani, M.P., "Morphable model of quadrupeds
skeletons for animating 3D animals
SIGGRAPH/Eurographics Symposium on Computer Animation
, Los Angeles,
USA, July 29-31, 2005.