Efficient elasticity for character skinning with contact and collisions

McAdamsAleka,; ZhuYongning,; SelleAndrew,; EmpeyMark,; Tamstorf, Rasmus; TeranJoseph,; SifakisEftychios,

doi:10.1145/2010324.1964932

Cited by 177 publications

(34 citation statements)

References 16 publications

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“…However, large‐enough edits will indubitably lead to visually noticeable artifacts and can even introduce self‐collisions (Figure ). Note also that our method is only guaranteed to be stable if the tangent stiffness matrices of the input sequence are positive definite: negative eigenvalues should be remedied using , for example, or . As future work, it may be interesting to adopt the configuration‐invariant linearization scheme or the adaptive dimension reduction instead to make our approach even more robust to large edits.…”

Section: Resultsmentioning

confidence: 99%

Interactive elastic motion editing through space–time position constraints

Huang

Desbrun

et al. 2013

Computer Animation & Virtual

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We present an intuitive and interactive approach for motion editing through space–time constraints on positions. Given an input motion of an elastic body, our approach enables the user to interactively edit node positions in order to alter and fine‐tune the motion. We formulate our motion editing as an optimization problem with dynamics constraints to enforce a physically plausible result. Through linearization of the editing around the input trajectory, we simplify this constrained optimal control problem into an unconstrained quadratic optimization. The optimal motion thus becomes the solution of a dense linear system, which we solve efficiently by applying the adjoint method in each iteration of a conjugate gradient solver. We demonstrate the efficiency and quality of our motion editing technique on a series of examples. Copyright © 2013 John Wiley & Sons, Ltd.

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Section: Resultsmentioning

confidence: 99%

Interactive elastic motion editing through space–time position constraints

Huang

Desbrun

et al. 2013

Computer Animation & Virtual

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“…To solve this problem, Müller et al proposed a corotational linear elastic model to guarantee the rotational invariance. Owing to its high efficiency and easy implementation, the model has been commonly employed and improved subsequently . Besides, there are also some nonlinear constitutive models that can solve the rotationally invariant problem.…”

Section: Related Workmentioning

confidence: 99%

An improved solution for deformation simulation of nonorthotropic geometric models

Cao

Yang

Ren

et al. 2019

Computer Animation & Virtual

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Physically based deformation simulation has been studied for many years in computer graphics. In order to simulate more complex geometric models and better meet the designer's requirements, many anisotropic approaches have been proposed in recent years. However, most of the approaches focus on simulating orthotropic models. In comparison with orthotropic models, nonorthotropic ones allow the objects to have anisotropic behaviors along nonorthogonal directions. In this paper, we introduce an improved approach to simulate nonorthotropic geometric models under large deformation. The improvements are mainly twofold. First, a frame field is specified on a given undeformed object, that is, each point of the object is equipped with a frame. In each local frame, we construct three independent vectors and form a nonorthogonal coordinate. Second, we design the deformation properties along each axis in the local nonorthogonal coordinate to get a local constitutive model. The final nonorthotropic model is generated by transforming the designed model from local nonorthogonal coordinates to the global standard Cartesian coordinate. To improve the stability, we introduce a time‐varying method to simultaneously track the local coordinates reorientation by pushing forward the original frame field to the deformed frame field. Experiments show that the deformation simulation using the designed nonorthotropic models exhibits anisotropic behaviors along different directions and are more stable than previous methods.

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“…This is true even if objects do not invert during the simulation, since the minimization procedure may still encounter such states. Examples of suitable constitutive models are those defined by the corotated hyperelasticity energy [27], [28], [29], [30], [31], [32] (but see Section 3.3), and the fixed corotated hyperelasticity variant [26]. Stress-based extrapolated models [33], [34] are unsuitable due to the lack of a potential energy function in the extrapolated regime, but energy-based extrapolation models [26] are fine.…”

Section: Elasticmentioning

confidence: 99%

Optimization Integrator for Large Time Steps

Gast

Schroeder

Stomakhin

et al. 2015

IEEE Trans. Visual. Comput. Graphics

114

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Practical time steps in today's state-of-the-art simulators typically rely on Newton's method to solve large systems of nonlinear equations. In practice, this works well for small time steps but is unreliable at large time steps at or near the frame rate, particularly for difficult or stiff simulations. We show that recasting backward Euler as a minimization problem allows Newton's method to be stabilized by standard optimization techniques with some novel improvements of our own. The resulting solver is capable of solving even the toughest simulations at the [Formula: see text] frame rate and beyond. We show how simple collisions can be incorporated directly into the solver through constrained minimization without sacrificing efficiency. We also present novel penalty collision formulations for self collisions and collisions against scripted bodies designed for the unique demands of this solver. Finally, we show that these techniques improve the behavior of Material Point Method (MPM) simulations by recasting it as an optimization problem.

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Efficient elasticity for character skinning with contact and collisions

Cited by 177 publications

References 16 publications

Interactive elastic motion editing through space–time position constraints

Interactive elastic motion editing through space–time position constraints

An improved solution for deformation simulation of nonorthotropic geometric models

Optimization Integrator for Large Time Steps

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