A Survey of Image-Based Techniques for Hair Modeling
TL;DR: This paper surveys the state of the art in the major topics of image-based techniques for hair modeling, including single-viewhair modeling, static hair modeling from multiple images, video-based dynamic hair modeled, and the editing and reusing of hair modeling results.
Abstract: With the tremendous performance increase of today’s graphics technologies, visual details of digital humans in games, online virtual worlds, and virtual reality applications are becoming significantly more demanding. Hair is a vital component of a person’s identity and can provide strong cues about age, background, and even personality. More and more researchers focus on hair modeling in the fields of computer graphics and virtual reality. Traditional methods are physics-based simulation by setting different parameters. The computation is expensive, and the constructing process is non-intuitive, difficult to control. Conversely, image-based methods have the advantages of fast modeling and high fidelity. This paper surveys the state of the art in the major topics of image-based techniques for hair modeling, including single-view hair modeling, static hair modeling from multiple images, video-based dynamic hair modeling, and the editing and reusing of hair modeling results. We first summarize the single-view approaches, which can be divided into the orientation-field and data-driven-based methods. The static methods from multiple images and dynamic methods are then reviewed in Sections III and IV . In Section V , we also review the editing and reusing of hair modeling results. The future development trends and challenges of image-based methods are proposed in the end.
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TL;DR: DeepSketchHair, a deep learning based tool for modeling of 3D hair from 2D sketches, takes as input a user-drawn sketch, and automatically generates a3D hair model, matching the input sketch.
Abstract: We present DeepSketchHair , a deep learning based tool for modeling of 3D hair from 2D sketches. Given a 3D bust model as reference, our sketching system takes as input a user-drawn sketch (consisting of hair contour and a few strokes indicating the hair growing direction within a hair region), and automatically generates a 3D hair model, matching the input sketch. The key enablers of our system are three carefully designed neural networks, namely, S2ONet , which converts an input sketch to a dense 2D hair orientation field; O2VNet , which maps the 2D orientation field to a 3D vector field; and V2VNet , which updates the 3D vector field with respect to the new sketches, enabling hair editing with additional sketches in new views. All the three networks are trained with synthetic data generated from a 3D hairstyle database. We demonstrate the effectiveness and expressiveness of our tool using a variety of hairstyles and also compare our method with prior art.
15 citations
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TL;DR: Sketchhair as discussed by the authors is a deep learning-based tool for interactive modeling of 3D hair from 2D sketches, which takes as input a user-drawn sketch (consisting of hair contour and a few strokes indicating the hair growing direction within a hair region).
Abstract: We present sketchhair, a deep learning based tool for interactive modeling of 3D hair from 2D sketches. Given a 3D bust model as reference, our sketching system takes as input a user-drawn sketch (consisting of hair contour and a few strokes indicating the hair growing direction within a hair region), and automatically generates a 3D hair model, which matches the input sketch both globally and locally. The key enablers of our system are two carefully designed neural networks, namely, S2ONet, which converts an input sketch to a dense 2D hair orientation field; and O2VNet, which maps the 2D orientation field to a 3D vector field. Our system also supports hair editing with additional sketches in new views. This is enabled by another deep neural network, V2VNet, which updates the 3D vector field with respect to the new sketches. All the three networks are trained with synthetic data generated from a 3D hairstyle database. We demonstrate the effectiveness and expressiveness of our tool using a variety of hairstyles and also compare our method with prior art.
6 citations
TL;DR: This work forms this 3-D approximation problem as a 2-D one, which increases its efficiency by one or even two orders of magnitude, and can be directly applied to cloth-body collision handling in real-time cloth animation.
Abstract: We present a method to approximate a mannequin represented as a triangle/quadrangle mesh using spheres and capsules. We formulate this 3-D approximation problem as a 2-D one, which increases its efficiency by one or even two orders of magnitude. Our algorithm first extracts cross sections from a given mannequin, approximates each cross section with circles using a variant of iterative Lloyd clustering, and finally generates capsules based on the circle sets. Compared with previous methods, our method is much faster and is able to get a tighter result with a given number of primitives. Our method can be directly applied to cloth-body collision handling in real-time cloth animation, and the simulation results by our approach are visually plausible.
5 citations
Additional excerpts
...In the future, we plan to add hair to the mannequin [40], [41] to obtain more realistic results....
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TL;DR: In this paper, the authors quantify the solar erythemal UV protection provided by human hair for different orientations and solar Zenith Angles (SZA) and find that hair with a certain degree of order (parallel alignment) were generally higher by a range of about 10% to 30% than the ones provided by random arrangements.
Abstract: The head is one of the most sun-exposed anatomical zones and its ultraviolet (UV) exposure is often underestimated. The goal of this research is to quantify the solar erythemal UV protection provided by human hair for different orientations and Solar Zenith Angles (SZA). For this purpose, a three-dimensional (3D) numeric simulation tool called SimUVEx was used to forecast the distribution of UV exposure based on geometric information and solar irradiance. The relative UV dose reduction was expressed in terms of predictive protection factor (PPF). Results showed that the effectiveness of the protection depends strongly on the orientation of the head and on the tilt of the hairs. As the SZA increases, the PPF also increases. PPFs provided by hair with a certain degree of order (parallel alignment) were generally higher by a range of about 10%–30% than the ones provided by random arrangements. A significant exposure to the scalp through the hair, even for an average hair density, was found. It confirms that hair is an important natural sunscreen in reducing transmission of UV radiation and must be considered in the prevention messages of skin cancer on the scalp, particularly in people with alopecia.
3 citations
01 Jun 2020
TL;DR: This paper introduces examples of viewpoint recommendation for two different input sketches and proposes a method to realize sketch-based hairstyle modeling efficiently by supporting a viewpoint recommendation technique.
Abstract: Hairstyle is an essential factor for representing individuals It is in demand for ordinary persons who are not experts of professional software on three-dimensional computer graphics (3DCG) to represent hairstyles with flexible hairstyle modeling using 3DCG We propose a method to realize sketch-based hairstyle modeling efficiently by supporting a viewpoint recommendation technique so that such users can easily perform hairstyle modeling This method automatically finds appropriate viewpoints by evaluating the shapes of sketches on the projected 2D space We aim to make this task of sketch-based hairstyle modeling efficient and straightforward because the technique avoids to manually control the viewpoint and prompts users to perform hair modeling intuitively This paper introduces examples of viewpoint recommendation for two different input sketches
2 citations
Additional excerpts
...Many recent techniques on hairstyle modeling are image-based [2]....
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References
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24 Jul 1998
TL;DR: A cloth simulation system that can stably take large time steps is described, which is significantly faster than previous accounts of cloth simulation systems in the literature.
Abstract: The bottle-neck in most cloth simulation systems is that time steps must be small to avoid numerical instability. This paper describes a cloth simulation system that can stably take large time steps. The simulation system couples a new technique for enforcing constraints on individual cloth particles with an implicit integration method. The simulator models cloth as a triangular mesh, with internal cloth forces derived using a simple continuum formulation that supports modeling operations such as local anisotropic stretch or compression; a unified treatment of damping forces is included as well. The implicit integration method generates a large, unbanded sparse linear system at each time step which is solved using a modified conjugate gradient method that simultaneously enforces particles’ constraints. The constraints are always maintained exactly, independent of the number of conjugate gradient iterations, which is typically small. The resulting simulation system is significantly faster than previous accounts of cloth simulation systems in the literature.
1,775 citations
"A Survey of Image-Based Techniques ..." refers methods in this paper
...Other approaches [63]–[65] used a constrained mass-spring model, well-suited for animating extensible wisps such as wavy or curly wisps....
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01 Aug 2008
TL;DR: In this article, a discrete treatment of adapted framed curves, parallel transport, and holonomy is presented for a discrete geometric model of thin flexible rods with arbitrary cross section and undeformed configuration.
Abstract: We present a discrete treatment of adapted framed curves, parallel transport, and holonomy, thus establishing the language for a discrete geometric model of thin flexible rods with arbitrary cross section and undeformed configuration. Our approach differs from existing simulation techniques in the graphics and mechanics literature both in the kinematic description---we represent the material frame by its angular deviation from the natural Bishop frame---as well as in the dynamical treatment---we treat the centerline as dynamic and the material frame as quasistatic. Additionally, we describe a manifold projection method for coupling rods to rigid-bodies and simultaneously enforcing rod inextensibility. The use of quasistatics and constraints provides an efficient treatment for stiff twisting and stretching modes; at the same time, we retain the dynamic bending of the centerline and accurately reproduce the coupling between bending and twisting modes. We validate the discrete rod model via quantitative buckling, stability, and coupled-mode experiments, and via qualitative knot-tying comparisons.
572 citations
"A Survey of Image-Based Techniques ..." refers methods in this paper
...The super-helix model has been widely used in hairstyle editing and reusing [45], [68]–[71], since it can be used to represent a variety of complex hairstyles....
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01 Jul 2006
TL;DR: This paper shows that the Kirchhoff equations for dynamic, inextensible elastic rods can be used for accurately predicting hair motion, and introduces a novel deformable model for solving them: each strand is represented by a Super-Helix, i.e., a piecewise helical rod which is animated using the principles of Lagrangian mechanics.
Abstract: Simulating human hair is recognized as one of the most difficult tasks in computer animation. In this paper, we show that the Kirchhoff equations for dynamic, inextensible elastic rods can be used for accurately predicting hair motion. These equations fully account for the nonlinear behavior of hair strands with respect to bending and twisting. We introduce a novel deformable model for solving them: each strand is represented by a Super-Helix, i.e., a piecewise helical rod which is animated using the principles of Lagrangian mechanics. This results in a realistic and stable simulation, allowing large time steps. Our second contribution is an in-depth validation of the Super-Helix model, carried out through a series of experiments based on the comparison of real and simulated hair motions. We show that our model efficiently handles a wide range of hair types with a high level of realism.
276 citations
TL;DR: This paper surveys the state of the art in the major topics of hair modeling: hairstyling, hair simulation, and hair rendering, presenting the unique challenges facing each area and describing solutions that have been presented over the years.
Abstract: Realistic hair modeling is a fundamental part of creating virtual humans in computer graphics. This paper surveys the state of the art in the major topics of hair modeling: hairstyling, hair simulation, and hair rendering. Because of the difficult, often unsolved problems that arise in alt these areas, a broad diversity of approaches is used, each with strengths that make it appropriate for particular applications. We discuss each of these major topics in turn, presenting the unique challenges facing each area and describing solutions that have been presented over the years to handle these complex issues. Finally, we outline some of the remaining computational challenges in hair modeling
275 citations
"A Survey of Image-Based Techniques ..." refers background in this paper
...INTRODUCTION Hair is a vital component of a person’s identity, which can provide strong cues about age, background and even personality [1]....
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01 Aug 2008
TL;DR: In this paper, a new altitude spring model is proposed to prevent collapse in the simulation of volumetric tetrahedra, and it is also applicable both to bending in cloth and torsion in hair.
Abstract: Our goal is to simulate the full hair geometry, consisting of approximately one hundred thousand hairs on a typical human head. This will require scalable methods that can simulate every hair as opposed to only a few guide hairs. Novel to this approach is that the individual hair/hair interactions can be modeled with physical parameters (friction, static attraction, etc.) at the scale of a single hair as opposed to clumped or continuum interactions. In this vein, we first propose a new altitude spring model for preventing collapse in the simulation of volumetric tetrahedra, and we show that it is also applicable both to bending in cloth and torsion in hair. We demonstrate that this new torsion model for hair behaves in a fashion similar to more sophisticated models with significantly reduced computational cost. For added efficiency, we introduce a semi-implicit discretization of standard springs that makes them truly linear in multiple spatial dimensions and thus unconditionally stable without requiring Newton-Raphson iteration. We also simulate complex hair/hair interactions including sticking and clumping behavior, collisions with objects (e.g. head and shoulders) and self-collisions. Notably, in line with our goal to simulate the full head of hair, we do not generate any new hairs at render time.
224 citations
"A Survey of Image-Based Techniques ..." refers background or methods in this paper
...One way to reconstruct a hair model is running physical simulation based on physical equations [17]–[19]....
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...Hair simulation results by mass-spring model [19]....
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...[19] extended the mass-spring model [2] to a new altitude-spring model that can model torsion....
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