Efficient and stable approach to elasticity and collisions for hair animation

Gornowicz, Galen; Borac, Silviu

doi:10.1145/2791261.2791271

Cited by 7 publications

(4 citation statements)

References 17 publications

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“…Prior work on rod-contact using constraints ] can avoid tunneling as long as the detection phase captures all contacts and the solver converges. More recent approaches [Gornowicz and Borac 2015;Kaufman et al 2014] improved stability using nonlinear Newton solves. In this paper, we adopt these improvements to non-smooth contact dynamics and further extend the method to handle cohesive effects.…”

Section: Strand Simulationmentioning

confidence: 99%

A multi-scale model for coupling strands with shear-dependent liquid

et al. 2019

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Fig. 1. Left: A rotating brush splashing through thick oil paint. The inset shows a zoomed view of paint on the bristles. Middle: Melted chocolate poured onto a hair-covered cylinder that rotates to mimic the shaking behavior of mammals. Right: Soba noodles covered with oyster sauce pulled upwards by a fork.We propose a framework for simulating the complex dynamics of strands interacting with compressible, shear-dependent liquids, such as oil paint, mud, cream, melted chocolate, and pasta sauce. Our framework contains three main components: the strands modeled as discrete rods, the bulk liquid represented as a continuum (material point method), and a reduced-dimensional flow of liquid on the surface of the strands with detailed elastoviscoplastic behavior. These three components are tightly coupled together. To enable discrete strands interacting with continuum-based liquid, we develop models that account for the volume change of the liquid as it passes through strands and the momentum exchange between the strands and the liquid. We also develop an extended constraint-based collision handling method that supports cohesion between strands. Furthermore, we present a principled method to preserve the total momentum of a strand and its surface flow, as well as an analytic plastic flow approach for Herschel-Bulkley fluid that enables stable semi-implicit integration at larger time steps. We explore a series of challenging scenarios, involving splashing, shaking, and agitating the liquid which causes the strands to stick together and become entangled.

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Section: Strand Simulationmentioning

confidence: 99%

A multi-scale model for coupling strands with shear-dependent liquid

et al. 2019

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“…Additionally, Iben et al [2013] proposed an artistic way to control curly hairs. As for collision between hairs, Kaufman et al [2014] combined a nonlinear integrator with a Gauss-Seidel collision solver, while Gornowicz and Borac [2015] proposed a hybrid algorithm for higher performance and better stability. To simulate the underlying dynamics of hair, we adopt the DER framework, and model both the cohesive and repulsive effects as constraints.…”

Section: Related Workmentioning

confidence: 99%

“…We solve them with a stable constraint solver [Tournier et al 2015] alongside a modified conjugate gradient preconditioner. We choose such an implementation for simplicity, although we believe more sophisticated integrators or constraint solvers [Gornowicz and Borac 2015;Kaufman et al 2014] could also be applied for the constraints proposed in this paper.…”

Section: Related Workmentioning

confidence: 99%

A multi-scale model for simulating liquid-hair interactions

et al. 2017

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Fig. 1. Hair is submerged in water and then rapidly flipped, resulting in wet locks and dripping.The diverse interactions between hair and liquid are complex and span multiple length scales, yet are central to the appearance of humans and animals in many situations. We therefore propose a novel multi-component simulation framework that treats many of the key physical mechanisms governing the dynamics of wet hair. The foundations of our approach are a discrete rod model for hair and a particle-in-cell model for fluids. To treat the thin layer of liquid that clings to the hair, we augment each hair strand with a height field representation. Our contribution is to develop the necessary physical and numerical models to evolve this new system and the interactions among its components. We develop a new reduced-dimensional liquid model to solve the motion of the liquid along the length of each hair, while accounting for its moving reference frame and influence on the hair dynamics. We derive a faithful model for surface tension-induced cohesion effects between adjacent hairs, based on the geometry of the liquid bridges that connect them. We adopt an empirically-validated drag model to treat the effects of coarse-scale interactions between hair and surrounding fluid, and propose new volume-conserving dripping and absorption strategies to transfer liquid between the reduced and particle-in-cell liquid representations. The synthesis of these techniques yields an effective wet hair simulator, which we use to animate hair flipping, an animal shaking itself dry, a spinning car wash roller brush dunked in liquid, and intricate hair coalescence effects, among several additional scenarios.

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“…Bergou et al (2010) later improve the efficiency in hair simulation by introduc-ing time-parallel reference frame in the representation of adapted framed curves. Other recent noteworthy articles (see for example Spillmann and Harders, 2010;Tang et al, 2010;Sueda et al, 2011, Huang et al, Tang et al, 2012bKir, 2014;Gornowicz and Borac, 2015 ) report on modeling discrete elastic rods with the Kirchhoff theory.…”

Section: Physical Based Simulationsmentioning

confidence: 99%

Real time simulation of inextensible surgical thread using a Kirchhoff rod model with force output for haptic feedback applications

Wang

Fratarcangeli

Ruimi

et al. 2017

International Journal of Solids and Structures

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International Journal of Solids and Structures (ISSN: 0020-7683)Citation for the published paper: Wang, Z. ; Fratarcangeli, M. ; Ruimi, A. et al. (2017) "Real time simulation of inextensible surgical thread using a Kirchhoff rod model with force output for haptic feedback applications". International Journal of Solids and Structures, http://dx.doi.org/10.1016/j.ijsolstr.2017.02.017Downloaded from: http://publications.lib.chalmers.se/publication/248860 Notice: Changes introduced as a result of publishing processes such as copy-editing and formatting may not be reflected in this document. For a definitive version of this work, please refer to the published source. Please note that access to the published version might require a subscription.Chalmers Publication Library (CPL) offers the possibility of retrieving research publications produced at Chalmers University of Technology. It covers all types of publications: articles, dissertations, licentiate theses, masters theses, conference papers, reports etc. Since 2006 it is the official tool for Chalmers official publication statistics. To ensure that Chalmers research results are disseminated as widely as possible, an Open Access Policy has been adopted. The CPL service is administrated and maintained by Chalmers Library.(article starts on next page)International Journal of Solids and Structures 113-114 (2017) 192-208 Contents lists available at ScienceDirect a b s t r a c tWe discuss the dynamics of an inextensible thin Kirchhoff rod used in the modeling of surgical threads, and demonstrate a very efficient scheme to not only simulate the motion of the thread in real-time (up to 1 ms per frame) but also obtain the constraint axial forces which can be fed back to a haptic system. The numerical scheme is based on a family of schemes called geometric or discrete variational integrators guaranteeing that the momentum and energy are exactly conserved over long periods of time for conservative systems. Besides, we report on an efficient numerical procedure to handle the inextensibility of the thread through physically based Lagrange multipliers, as well as the internal dissipation of the thread. We have performed simulations to verify the capabilities of our model to conserve momentum and energy, accurately calculate the axial constraint forces along the thread for haptic feedback, and capture bending-torsion coupling leading to the formation of plectonemes. While many of the ideas are well known in the computer graphics community (especially in hair modeling), we have implemented several improvements for the specific purpose of speeding up the computations for developing physically based haptic interfaces for knot tying and suturing.

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Efficient and stable approach to elasticity and collisions for hair animation

Cited by 7 publications

References 17 publications

A multi-scale model for coupling strands with shear-dependent liquid

A multi-scale model for coupling strands with shear-dependent liquid

A multi-scale model for simulating liquid-hair interactions

Real time simulation of inextensible surgical thread using a Kirchhoff rod model with force output for haptic feedback applications

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