Non-Photorealistic Computer Graphics Library

N-way morphing for 2D animation

Author(s): William Baxter, Pascal Barla, Ken Anjyo.
Article: Computer Animation and Virtual Worlds, Vol. 20, No. 2-3, pp. 79--87, 2009.
[BibTeX] [DOI]

Abstract:
We present a novel approach to the creation of varied animations from a small set of simple 2D input shapes. Instead of providing a new 2D shape for each keyframe of an animation sequence, we interpolate between a few example shapes in a reduced pose-space. Similar approaches have been presented in the past, but were restricted in the types of input or range of deformations allowed. In order to address these limitations, we reformulate the problem as an N-way morphing process on 2D input bitmap or vector graphics. Our formulation includes an N-way mapping technique, an efficient, rigidity preserving nonlinear blending function, improved extrapolation and a novel scattered data interpolation technique to manage the reduced pose-space. The resulting animations are correlated to paths in the reduced pose-space, allowing users to intuitively and interactively control temporal behaviours with simple gestures. We demonstrate our techniques in several example animations.