Computer Graphics Laboratory ETH Zurich


Rig-Space Physics

F. Hahn, S. Martin, B. Thomaszewski, R. Sumner, S. Coros, M. Gross

Proceedings of ACM SIGGRAPH (Los Angeles, USA, August 5-9, 2012), ACM Transactions on Graphics, vol. 31, no. 4, pp. 72:1-72:8
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We present a method that brings the benefits of physics-based simulations to traditional animation pipelines. We formulate the equations of motions in the subspace of deformations defined by an animator's rig. Our framework fits seamlessly into the workflow typically employed by artists, as our output consists of animation curves that are identical in nature to the result of manual keyframing. Artists can therefore explore the full spectrum between hand-crafted animation and unrestricted physical simulation. To enhance the artist's control, we provide a method that transforms stiffness values defined on rig parameters to a non-homogeneous distribution of material parameters for the underlying FEM model. In addition, we use automatically extracted high-level rig parameters to intuitively edit the results of our simulations, and also to speed up computation. To demonstrate the effectiveness of our method, we create compelling results by adding rich physical motions to coarse input animations. In the absence of artist input, we create realistic passive motion directly in rig space.

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author = {Hahn, Fabian and Martin, Sebastian and Thomaszewski, Bernhard and Sumner, Robert and Coros, Stelian and Gross, Markus},
title = {Rig-space physics},
journal = {ACM Trans. Graph.},
issue_date = {July 2012},
volume = {31},
number = {4},
month = jul,
year = {2012},
issn = {0730-0301},
pages = {72:1--72:8},
articleno = {72},
numpages = {8},
url = {},
doi = {10.1145/2185520.2185568},
acmid = {2185568},
publisher = {ACM},
address = {New York, NY, USA},
keywords = {animation control, physically-based simulation},
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