Simulation and control of skeleton-driven soft body characters

Liu, Libin; Yin, KangKang; Wang, Bin; Guo, Baining

doi:10.1145/2508363.2508427

Cited by 66 publications

(45 citation statements)

References 42 publications

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“…Other, faster methods use geometries that are orders of magnitude simpler, e.g. 4160 [Liu et al 2013] and 8619 [Kim and Pollard 2011] elements. Our method offers clear advantages for both computational and geometric complexity.…”

Section: Resultsmentioning

confidence: 99%

“…In addition to their use in feature animation [Clutterbuck and Jacobs 2010], realistic virtual humans also have numerous medical applications [Hirota et al 2001]. Thus, many efficient methods have been developed, including co-rotational elasticity and multigrid solvers [Zhu et al 2010;McAdams et al 2011;Liu et al 2013]. These full-rank methods are complementary to our current approach.…”

Section: Related Workmentioning

confidence: 99%

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Simulating articulated subspace self-contact

Teng

Otaduy²,

Kim

2014

ACM Trans. Graph.

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Figure 1: A hand mesh composed of 458K tetrahedra, running at 5.8 FPS (171 ms), including both self-contact detection and resolution. Our algorithm accelerates the computation of complex self-contacts by a factor of 5× to 52× over other subspace methods and 166× to 391× over full-rank simulations. Our self-contact computation never dominates the total time, and takes up at most 46% of a single frame. AbstractWe present an efficient new subspace method for simulating the self-contact of articulated deformable bodies, such as characters. Self-contact is highly structured in this setting, as the limited space of possible articulations produces a predictable set of coherent collisions. Subspace methods can leverage this coherence, and have been used in the past to accelerate the collision detection stage of contact simulation. We show that these methods can be used to accelerate the entire contact computation, and allow self-contact to be resolved without looking at all of the contact points. Our analysis of the problem yields a broader insight into the types of nonlinearities that subspace methods can efficiently approximate, and leads us to design a pose-space cubature scheme. Our algorithm accelerates self-contact by up to an order of magnitude over other subspace simulations, and accelerates the overall simulation by two orders of magnitude over full-rank simulations. We demonstrate the simulation of high resolution (100K -400K elements) meshes in self-contact at interactive rates (5.8 -50 FPS).

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Section: Resultsmentioning

confidence: 99%

Section: Related Workmentioning

confidence: 99%

Simulating articulated subspace self-contact

Teng

Otaduy²,

Kim

2014

ACM Trans. Graph.

View full text Add to dashboard Cite

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“…The most widely used skinning model for character animation to date is skeleton-based skinning. A skeleton pose can be used to determine the skin deformation, with the consideration of physical properties including elasticity, contact, collision [McAdams et al 2011;Hahn et al 2012;Liu et al 2013], and even the anatomy of creatures [Lee et al 2009;Ali-Hamadi et al 2013]. To achieve real time performance, geometric skinning methods can simply blend bone transformations to produce the skin using a set of blending weights for each vertex [Merry et al 2006;Kavan et al 2008;Kavan and Sorkine 2012;Le and Deng 2013;Vaillant et al 2013].…”

Section: Related Workmentioning

confidence: 99%

Robust and accurate skeletal rigging from mesh sequences

Deng

2014

ACM Trans. Graph.

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Figure 1: Only using a single set of parameters, our example-based method can accurately rig various models such as quadrupled animals (a), humans (b, c), and highly deformable models (d). Our method can even generate bone structures for challenging parts, such as the mouth and the two ears of the cat (a), the skirt (b), and the elastic cow model (d). Our method is robust: using only 9 frames, it can generate a skeleton with 28 bones for the cat model (a); note that even though the given example poses of the cat model have asymmetric poses, it still can generate an almost symmetric skeleton without imposing any symmetry constraints. AbstractWe introduce an example-based rigging approach to automatically generate linear blend skinning models with skeletal structure. Based on a set of example poses, our approach can output its skeleton, joint positions, linear blend skinning weights, and corresponding bone transformations. The output can be directly used to set up skeleton-based animation in various 3D modeling and animation software as well as game engines. Specifically, we formulate the solving of a linear blend skinning model with a skeleton as an optimization with joint constraints and weight smoothness regularization, and solve it using an iterative rigging algorithm that (i) alternatively updates skinning weights, joint locations, and bone transformations, and (ii) automatically prunes redundant bones that can be generated by an over-estimated bone initialization. Due to the automatic redundant bone pruning, our approach is more robust than existing example-based rigging approaches. Furthermore, in terms of rigging accuracy, even with a single set of parameters, our approach can soundly outperform state of the art methods on various types of experimental datasets including humans, quadrupled animals, and highly deformable models.

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“…Changing the reference shapes for plasticity simulation has been introduced to computer graphics [Bargteil et al 2007;Wicke et al 2010;Fan et al 2013]. Several authors have also used target poses or rest shapes for animating and controlling arbitrary soft bodies Schumacher et al 2012;Liu et al 2013]. In muscle biomechanics, multiplicative plasticity laws have been used to simulate deformation of active muscle [Nardinocchi and Teresi 2007], which provides some biological support for our model.…”

Section: Figurementioning

confidence: 99%

Active volumetric musculoskeletal systems

2014

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Figure 1: Our framework spans the entire pipeline for simulating volumetric musculoskeletal systems, starting from data on the active shapes of muscles to physically based simulation of muscles and soft tissues coupled to the skeletal system. (a) MRI 1 of the eye can reveal both passive and active muscle shapes. (b) Reconstructed muscle shapes. (c) Physically based simulation of an individual's eye movement using our system. (d) Upper arm with six muscles and a bone in close sliding contact with each other. Volume preservation produces realistic lateral bulging. (e) Dynamic simulation of arm with soft tissues, a soft glove, and contact with the environment. AbstractWe introduce a new framework for simulating the dynamics of musculoskeletal systems, with volumetric muscles in close contact and a novel data-driven muscle activation model. Muscles are simulated using an Eulerian-on-Lagrangian discretization that handles volume preservation, large deformation, and close contact between adjacent tissues. Volume preservation is crucial for accurately capturing the dynamics of muscles and other biological tissues. We show how to couple the dynamics of soft tissues with Lagrangian multibody dynamics simulators, which are widely available. Our physiologically based muscle activation model utilizes knowledge of the active shapes of muscles, which can be easily obtained from medical imaging data or designed to meet artistic needs. We demonstrate results with models derived from MRI data and models designed for artistic effect.

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Simulation and control of skeleton-driven soft body characters

Cited by 66 publications

References 42 publications

Simulating articulated subspace self-contact

Simulating articulated subspace self-contact

Robust and accurate skeletal rigging from mesh sequences

Active volumetric musculoskeletal systems

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