Natsuko Tanaka

Bio: Natsuko Tanaka is an academic researcher from Joshibi University of Art and Design. The author has contributed to research in topics: Animation & Cel. The author has an hindex of 2, co-authored 3 publications receiving 9 citations.

Hair motion cloning from cartoon animation sequences

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.

Anime hair motion design from animation database

Abstract: This paper describes a new method to animate anime-like hair motion that allows users to use existing cel character animation sequences. We demonstrate how to create cartoon hair animation accentuated in anime-like motions. The novelty of this approach is that users can extract the motion from the existing cel animation such as windy scene or motion of grass and fire etc. Then, they can apply the extracted motion to other characters with a three-dimensional structure. In fact, users can re-use existing anime sequences as input to animate another character as if both characters existed in the same environment. Also, creating abundant hair motion database from various animator's characteristic hair motion enables users to create the hair motion that has user's favorite kind of the animator's characteristic even though a user is not an animator.

Hair motion re-modeling from cartoon animation sequence

Abstract: The creation of hair is specialized work in cel animation that is challenging to achieve in 3DCG because cel animation may not be consistent with all the hair’s features from all camera positions [Noble and Tang 2004]. This paper describes a new approach for cartoon hair animation by using an existing character animation sequence. The novelty of this method is that a creator can easily make a 3D character model to apply environmental information such as winds in an existing character animation with hair. In fact, the user can re-use existing cartoon sequences as inputs to give environmental information to another character as if both characters existed in the same scene.

Tweakable Shadows for Cartoon Animation

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.

Procedural Hair Generation

Abstract: This paper presents a hair generation technique for cartoon and Anime characters. The main goal of this work is to provide a procedural generation technique, robust enough in order to create different types of hairs. We propose a parametric model that can produce diversity of obtained results through parameters variation. The model is organized in three steps: firstly, the strands generation, followed by positioning them in the head of the characters. Finally, the third step is responsible for providing cartoon rendering, including common characteristics in cartoon shading, as the black edges and solid colors. Visual inspection of obtained results indicate that generated hairs are coherent with expected in terms of visual aspects.

Simulation-based in-between creation for CACAni 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].

A Simple Method to Animate Vegetation in Images Using Simulation-Guided Grid-Based Warping

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.

Directable and stylized hair simulation

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.