In this work, we describe a new and simple approach to re-use skeleton of animation with joint-based Laplacian-type regularization, in the context of exaggerated skeleton-based character animation. Despite decades of research, interactive character animations still have a lack of flexibility and editability in order to re-use real vertebral motion. In further details, generation of expressive cartoon animation from real data, is a challenging key task for nonphotorealistic animation. Hence, a major problem for artists in production is to enhance the expressiveness of classical motion clips by direct manipulation of the underlying skeletal structure. Relatively small number of researchers present their approach for processing cartoon effects on motion data in [Kwon and Lee 2007; Davis and Kannappan 2002; Bregler et al. 2002]. However existing techniques often avoid dealing with the potential of skeletal-based optimization, while preserving the joint coherence and connectivity. Besides, the majority of characters in cartoons have the flexibility to stretch to extreme positions and squash to astounding shapes. It can also be noticed that squash-and-stretch is easier to realize in traditional animation rather than mocap-based computer generated animation. For this reason, Ratatouille a Pixar movie, did not use a rigid skeleton, while abandoning motion capture to reach such essential non-ultra realistic appeal.

Stretchable Cartoon Editing for Skeletal Captured Animations
Yann Savoye
SIGGRAPH ASIA '11: ACM SIGGRAPH ASIA 2011 Technical Sketches, Hong Kong,
China. December 13-15, 2011 (acceptance rate: 22.6%) - Lead Session Sketch

@inproceedings{Savoye2011b,
author = {Savoye, Yann},
title = {Stretchable cartoon editing for skeletal captured animations},
booktitle = {SIGGRAPH Asia 2011 Sketches},
series = {SA '11},
year = {2011},
isbn = {978-1-4503-1138-0},
location = {Hong Kong, China},
pages = {5:1--5:2},
articleno = {5},
numpages = {2},
acmid = {2077385},
publisher = {ACM},
address = {New York, NY, USA},
}

skeleton of animation, joint-based Laplacian-type regularization, exaggerated skeleton-based character animation, expressive cartoon animation, non-photorealistic animation. skeletal-based optimization, squash-and-stretch.