Efficient Dynamic Skinning with Low-Rank Helper Bone Controllers

ACM Transactions on Graphics (TOG) – Proceedings of ACM SIGGRAPH 2016, Volume 35, Issue 4, Article No. 36

Authors: Tomohiko Mukai and Shigeru Kuriyama

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Abstract: Dynamic skin deformation is vital for creating life-like characters, and its real-time computation is in great demand in interactive applications. We propose a practical method to synthesize plausible and dynamic skin deformation based on a helper bone rig. This method builds helper bone controllers for the deformations caused not only by skeleton poses but also secondary dynamics effects. We introduce a state-space model for a discrete time linear time-invariant system that efficiently maps the skeleton motion to the dynamic movement of the helper bones. Optimal transfer of non-linear, complicated deformations, including the effect of soft-tissue dynamics, is obtained by learning the training sequence consisting of skeleton motions and corresponding skin deformations. Our approximation method for a dynamics model is highly accurate and efficient owing to its low-rank property obtained by a sparsity-oriented nuclear norm optimization. The resulting linear model is simple enough to easily implement in the existing workflows and graphics pipelines. We demonstrate the superior performance of our method compared to conventional dynamic skinning in terms of computational efficiency including LOD controls, stability in interactive controls, and flexible expression in deformations.

Acknowledgements: We thank TAISO, Renpoo for making the human character model available at http://www.behind-universe.org/ and for many helpful comments. This work was supported by JSPS KAKENHI Grant Number 15K16110, 15H02704.

¬©ACM 2016. This is the author’s version of the work. It is posted here for your personal use. Not for redistribution. The definitive Version of Record was published in SIGGRAPH ’16 Technical Papers, http://dx.doi.org/10.1145/2897824.2925905