Modeling Dynamic Hair as a Continuum

Hadap, Sunil; Magnenat‐Thalmann, Nadia

doi:10.1111/1467-8659.00525

Cited by 119 publications

(84 citation statements)

References 10 publications

(8 reference statements)

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“…While some early methods have focused on hair keyframing animation [Koh and Huang 2000], most recent techniques have attempted to simulate hair using a physics-based model accounting for the law of mechanics [Anjyo et al 1992;Plante et al 2001;Hadap and Magnenat-Thalmann 2001;Chang et al 2002;Bertails et al 2006;Hadap 2006]. Such simulations were for long limited in complexity and resolution due to computational overhead.…”

Section: Related Workmentioning

confidence: 99%

Inverse dynamic hair modeling with frictional contact

et al. 2013

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Figure 1: Our inversion method makes the hair synthesis pipeline consistent: (a) Raw hair geometry (a set of polylines) resulting from the manual design or the automatic capture of a static hairstyle (here, a capture from [Herrera et al. 2012]); (b) Input geometry is automatically converted into a dynamic hair model (a set of super-helices) at equilibrium under gravity and frictional hair-body and hair-hair contact forces; Unlike classical hair simulators (c) which ignore surrounding forces when initializing the hairstyle and are thus prone to undesired sagging, our simulator (b) exactly matches the original hair geometry at initial state and (d) yields a realistic, character-specific hair animation. AbstractIn the latest years, considerable progress has been achieved for accurately acquiring the geometry of human hair, thus largely improving the realism of virtual characters. In parallel, rich physics-based simulators have been successfully designed to capture the intricate dynamics of hair due to contact and friction. However, at the moment there exists no consistent pipeline for converting a given hair geometry into a realistic physics-based hair model. Current approaches simply initialize the hair simulator with the input geometry in the absence of external forces. This results in an undesired sagging effect when the dynamic simulation is started, which basically ruins all the efforts put into the accurate design and/or capture of the input hairstyle. In this paper we propose the first method which consistently and robustly accounts for surrounding forcesgravity and frictional contacts, including hair self-contacts -when converting a geometric hairstyle into a physics-based hair model. Taking an arbitrary hair geometry as input together with a corresponding body mesh, we interpret the hair shape as a static equilibrium configuration of a hair simulator, in the presence of gravity as well as hair-body and hair-hair frictional contacts. Assuming that hair parameters are homogeneous and lie in a plausible range of physical values, we show that this large underdetermined inverse problem can be formulated as a well-posed constrained optimization problem, which can be solved robustly and efficiently by leveraging the frictional contact solver of the direct hair simulator. Our method was successfully applied to the animation of various hair geometries, ranging from synthetic hairstyles manually designed by an artist to the most recent human hair data automatically reconstructed from capture.

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Section: Related Workmentioning

confidence: 99%

Inverse dynamic hair modeling with frictional contact

et al. 2013

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“…A few authors have treated hair itself as a fluid-like material, either to approximate internal forces [Hadap and Magnenat-Thalmann 2001] or to accelerate collision processing [McAdams et al 2009]. …”

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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“…Hadap et al [2001] modeled hair as a serial rigid multibody chain and incorporated fluid dynamics to model hair collisions and contacts. Plante et al [2002] constrained a mass-spring system to a deformable envelope defining a volume of the cluster of hairs (wisp), which was also used for interactions.…”

Section: Related Workmentioning

confidence: 99%

Artistic simulation of curly hair

Iben¹,

Meyer²,

Petrović³

et al. 2013

Proceedings of the 12th ACM SIGGRAPH/Eurographics Symposium on Computer Animation

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We present a novel method for stably simulating stylized curly hair that addresses artistic needs and performance demands, both found in the production of feature films. To satisfy the artistic requirement of maintaining the curl's helical shape during motion, we propose a hair model based upon an extensible elastic rod. We introduce a novel method for stably computing a frame along the hair curve, essential for stable simulation of curly hair. Our hair model introduces a novel spring for controlling the bending of the curl and another for maintaining the helical shape during extension. We also address performance concerns often associated with handling hairhair contact interactions by efficiently parallelizing the simulation. To do so, we present a novel algorithm for pruning both hair-hair contact pairs and hair particles. Our method is in use on a full length feature film and has proven to be robust and stable over a wide range of animated motion and on a variety of hair styles, from straight to wavy to curly.

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Modeling Dynamic Hair as a Continuum

Cited by 119 publications

References 10 publications

Inverse dynamic hair modeling with frictional contact

Inverse dynamic hair modeling with frictional contact

A multi-scale model for simulating liquid-hair interactions

Artistic simulation of curly hair

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