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Journal ArticleDOI

Hair motion cloning from cartoon animation sequences

01 Jul 2006-Computer Animation and Virtual Worlds (John Wiley & Sons, Ltd)-Vol. 17, pp 491-499
TL;DR: A new approach to create cartoon hair animation that allows users to use existing cel character animation sequences and reuse existing cartoon sequences as input to endow another character with environmental elements as if both characters exist in the same scene.
Abstract: This paper describes a new approach to create cartoon hair animation that allows users to use existing cel character animation sequences. We demonstrate the generation of cartoon hair animation accentuated in ‘anime-like’ motions. The novelty of this method is that users can choose the existing cel animation of a character's hair animation and apply environmental elements such as wind to other characters with a three-dimensional structure. In fact, users can reuse existing cartoon sequences as input to endow another character with environmental elements as if both characters exist in the same scene. A three-dimensional character's hair motions are created based on hair motions from input cartoon animation sequences. First, users extract hair shapes at each frame from input sequences from which they then construct physical equations. ‘Anime-like’ hair motion is created by using these physical equations. Copyright © 2006 John Wiley & Sons, Ltd.
Citations
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Proceedings Article
01 Dec 2007
TL;DR: This paper proposes a novel method for editing the shadow with both advantages of hand drawn animation and 3DCG technology, and enables animators to edit the shadow by simple mouse operations.
Abstract: The role of shadow is important in cartoon animation. Shadows in hand-drawn animation reflect the expression of the animators' style, rather than mere physical phenomena. However shadows in 3DCG cannot express such an animators' touch. In this paper we propose a novel method for editing the shadow with both advantages of hand drawn animation and 3DCG technology. In particular, we discuss two phases that enable animators to transform and deform the shadow tweakably. The first phase is that a shadow projection matrix is applied to deform the shape of the shadow. The second one is that we manipulate vectors to transform the shadow such as scaling and translation. These vectors are used in shadow volume method. The shadows are edited directably by integration of these two phases. Our approach enables animators to edit the shadow by simple mouse operations. As a result, the animators can not only produce shadows automatically but also reflect their style easily. Once the shape and location of shadow are decided by animators' style in our method, 3DCG techniques can produce consistent shadow in object motion interactively.

6 citations

Proceedings ArticleDOI
16 Dec 2009
TL;DR: An in-between creation method, specialized for hair based on dynamic simulation, which does not need any 3D character model, which can directly utilize the hand-drawn key-frames which are drawn by animators in CACAni (Computer-Ass Cel Animation) system.
Abstract: In-between creation in traditional cel animation based on the hand-drawn key-frames is a fundamental element for the actual production and plays a symbolic role in an artistic interpretation of the scene. To create impressive in-betweens, however, animators are required to be skilled for hair animation creation. In the traditional cel animation, hair motions are generally used to express a character's affective change or showing environment condition. Despite this usability and importance, the hair motion is drawn relatively simply or is not animated at all because of the lack of skilled animators and time constraints in cel animation production. To assist this production process, P. Noble and W. Tang [Noble and Tang. 2004], and Sugisaki et al. [Sugisaki et al. 2006] introduced certain ways to create hair motion for cartoon animations. Both of them created the hair motion based on 3D simulation that is applied to the prepared 3D character model. In this paper, we introduce an in-between creation method, specialized for hair based on dynamic simulation, which does not need any 3D character model. Animators can create in-between frames for hair motion by setting a few parameters, and then our method automatically select the best in-between frames based on the specified frame number by animator. The advantage of our method is to create in-between frames for hair motion by applying simulation model to key-frames. Obviously, the key-frame images do not have any depth. In fact, our method can directly utilize the hand-drawn key-frames which are drawn by animators in CACAni (Computer-Assisted Cel Animation) system [CACAni Website].

4 citations

Proceedings ArticleDOI
16 Nov 2013
TL;DR: The proposed method enables users to interactively animate vegetation in real-time and produce natural-looking output motions comparable with real cartoons, suitable for simulating vegetation-wind interaction for a dense vegetation field which exhibit non-rigid property.
Abstract: In this paper, we propose a simple method to animate vegetation in images. The proposed method enables users to interactively animate vegetation in real-time. It can be used to enhance a vegetation photograph or painting with animated motions as well as to help animators to create cartoon animation of vegetation. Our method is suitable for simulating vegetation-wind interaction for a dense vegetation field which exhibit non-rigid property, especially in cartoon style images. In our method, wind field is modeled using fluid simulation. We adopt a harmonic oscillator based on wave simulation as the numerical model for the dynamics of vegetation. The velocity generated from the wind field is used to drive the wave simulation to determine the velocity of vegetation. Based on the velocity of vegetation, we employ a grid-based warping approach to animate different types of vegetation such as grass and trees. As a result, for vegetation in images, we can simulate grass and trees swaying in wind as well as under water plants swaying in water. Our method can produce natural-looking output motions comparable with real cartoons. Users can interactively control the location of the source, direction and strength of the wind or water flow and the property of vegetation on the fly.

4 citations


Additional excerpts

  • ...proposed simulation [35] and data-driven [36] approaches....

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Proceedings Article
13 Nov 2008
TL;DR: This paper proposes the use of External Force Field (EFF) to construct hair motion using a motion capture system and develops a system for editing the hair motion obtained using this process and applies this system to produce creator-oriented hair animation.
Abstract: Creating natural looking hair motion is considered to be one of the most difficult and time consuming challenges in CG animation. A detailed physics-based model is essential in creating convincing hair animation. However, hair animation created using detailed hair dynamics might not always be the result desired by creators. For this reason, a hair simulation system that is both detailed and editable is required in contemporary Computer Graphics. In this paper we therefore, propose the use of External Force Field (EFF) to construct hair motion using a motion capture system. Furthermore, we have developed a system for editing the hair motion obtained using this process. First, the environment around a subject is captured using a motion capture system and the EFF is defined. Second, we apply our EFF-based hair motion editing system to produce creator-oriented hair animation. Consequently, our editing system enables creators to develop desired hair animation intuitively without physical discontinuity.

2 citations


Cites background from "Hair motion cloning from cartoon an..."

  • ...Each rigid body has 2 degrees of freedom (angles of spherical coordinate) and the motion of rigid body is represented by the following equation (Sugisaki et al., 2006)....

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Dissertation
01 Jan 2010
TL;DR: It is suggested that the manuscript should be rewritten in a chapters-by- chapters format to facilitate more detailed discussion of the background work and its implications.
Abstract: ........................................................................................................................... i Acknowledgments ......................................................................................................... iv Table of
References
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Proceedings ArticleDOI
01 Aug 1987
TL;DR: The basic principles of traditional 2D hand drawn animation and their application to 3D computer animation are described and how these principles evolved is described.
Abstract: This paper describes the basic principles of traditional 2D hand drawn animation and their application to 3D computer animation. After describing how these principles evolved, the individual principles are detailed, addressing their meanings in 2D hand drawn animation and their application to 3D computer animation. This should demonstrate the importance of these principles to quality 3D computer animation.

740 citations


"Hair motion cloning from cartoon an..." refers background in this paper

  • ...Equation (4) represents how to define hair stiffness....

    [...]

Journal ArticleDOI
01 Jul 2005
TL;DR: A novel technique for large deformations on 3D meshes using the volumetric graph Laplacian is presented, allowing novice users to create pleasing deformations with little effort in a 2D curve-based deformation system.
Abstract: We present a novel technique for large deformations on 3D meshes using the volumetric graph Laplacian. We first construct a graph representing the volume inside the input mesh. The graph need not form a solid meshing of the input mesh's interior; its edges simply connect nearby points in the volume. This graph's Laplacian encodes volumetric details as the difference between each point in the graph and the average of its neighbors. Preserving these volumetric details during deformation imposes a volumetric constraint that prevents unnatural changes in volume. We also include in the graph points a short distance outside the mesh to avoid local self-intersections. Volumetric detail preservation is represented by a quadric energy function. Minimizing it preserves details in a least-squares sense, distributing error uniformly over the whole deformed mesh. It can also be combined with conventional constraints involving surface positions, details or smoothness, and efficiently minimized by solving a sparse linear system.We apply this technique in a 2D curve-based deformation system allowing novice users to create pleasing deformations with little effort. A novel application of this system is to apply nonrigid and exaggerated deformations of 2D cartoon characters to 3D meshes. We demonstrate our system's potential with several examples.

366 citations

Proceedings ArticleDOI
01 Jul 1992
TL;DR: A simple differential equation method is proposed for modeling the aesthetic features of human hair, which allows hairdressing variations with volumetric and realistic appearance and gives visually satisfactory results by solving the projective equations under a ps~udo-force field.
Abstract: A simple differential equation method is proposed for modeling the aesthetic features of human hair. In the method, a simplified cantilever beam simulation is employed for hairstyle modeling, which allows hairdressing variations with volumetric and realistic appearance. In order to describe the dynamical behavior of hair in an animation, one-dimensional projective differential equations of angular momenta for linked rigid sticks are also derived. For the problem of collision detection between hair and a human head, the “rough” approximate solution is provided, which gives visually satisfactory results by solving the projective equations under a ps~udo-force field. The hair’s pliability can be controlled by using a set of stiffness parameters in the method. In addition, a fast rendering technique for anisotropic reflection is introduced, which is derived from Blirm’s specular model. The efficiency of the proposed method is illustrated by the still images and short animations obtained. CR

258 citations


"Hair motion cloning from cartoon an..." refers background in this paper

  • ...θ̈ij(t) = 2(θij(t + s) − θij(t)) − sω(t) s2 (1)...

    [...]

  • ...Physical simulation is expressed by the following equations: θ̈ij(t) = 2(θij(t + s) − θij(t)) − sω(t) s2 (1) Hij = Iij θ̈ij(t) (2) θ̈ij can be obtained by Equation (1), where θ̈ij is angular acceleration, i is the number of hair strands, j is the joint number from the hair root, s is the time between frames, and ω is the angular velocity....

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  • ...Using Equation (5), motion suitable for the scene is achieved....

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  • ...We use Equation (3) from here....

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  • ...θ̈ij can be obtained by Equation (1), where θ̈ij is angular acceleration, i is the number of hair strands, j is the joint number from the hair root, s is the time between frames, and ω is the angular velocity....

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Journal ArticleDOI
TL;DR: This paper develops an elaborate model for stiffness and inertial dynamics of individual hair strand, which is numerically stable and fast, and unifies the continuum interaction dynamics and the individual hair's stiffness dynamics.
Abstract: In this paper we address the difficult problem of hair dynamics, particularly hair-hair and hair-air interactions. To model these interactions, we propose to consider hair volume as a continuum. Subsequently, we treat the interaction dynamics to be fluid dynamics. This proves to be a strong as well as viable approach for an otherwise very complex phenomenon. However, we retain the individual character of hair, which is vital to visually realistic rendering of hair animation. For that, we develop an elaborate model for stiffness and inertial dynamics of individual hair strand. Being a reduced coordinate formulation, the stiffness dynamics is numerically stable and fast. We then unify the continuum interaction dynamics and the individual hair’s stiffness dynamics.

192 citations


"Hair motion cloning from cartoon an..." refers background in this paper

  • ...Equation (2) can be denoted as Equation (3)....

    [...]

  • ...Equation (2) is the physical equation for each joint, where...

    [...]

Proceedings ArticleDOI
01 Jul 1999
TL;DR: This work presents a technique called View-Dependent Geometry, wherein a 3D model changes shape based on the direction it is viewed from, thereby capturing the view- dependent distortions of the reference drawings.
Abstract: When constructing 3D geometry for use in cel animation, the reference drawings of the object or character often contain various view-specific distortions, which cannot be captured with conventional 3D models. In this work we present a technique called View-Dependent Geometry, wherein a 3D model changes shape based on the direction it is viewed from. A view-dependent model consists of a base model, a set of key deformations (deformed versions of the base model), and a set of corresponding key viewpoints (which relate each 2D reference drawing to the 3D base model). Given an arbitrary viewpoint, our method interpolates the key deformations to generate a 3D model that is specific to the new viewpoint, thereby capturing the view- dependent distortions of the reference drawings.

146 citations