  We present CharacterMixer, a system for blending two rigged 3D characters
with different mesh and skeleton topologies while maintaining a rig throughout
interpolation. CharacterMixer also enables interpolation during motion for such
characters, a novel feature. Interpolation is an important shape editing
operation, but prior methods have limitations when applied to rigged
characters: they either ignore the rig (making interpolated characters no
longer posable) or use a fixed rig and mesh topology. To handle different mesh
topologies, CharacterMixer uses a signed distance field (SDF) representation of
character shapes, with one SDF per bone. To handle different skeleton
topologies, it computes a hierarchical correspondence between source and target
character skeletons and interpolates the SDFs of corresponding bones. This
correspondence also allows the creation of a single "unified skeleton" for
posing and animating interpolated characters. We show that CharacterMixer
produces qualitatively better interpolation results than two state-of-the-art
methods while preserving a rig throughout interpolation.
