研究成果

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[Journal] 基本速度場による流体アニメーションの高解像度化
佐藤周平, 森田拓也, 土橋宜典, 山本強
電子情報通信学会論文誌 D, Vol.J96-D, No.2, pp. 338-345, 2013.2 (Online ISSN: 1881-0225)
近年,流体解析を用いて写実的な水や炎などを表現する研究が数多く行われており,それらの方法を利用して生成された映像が映画やゲームなどに数多く用いられている.しかし,流体シミュレーションは計算コストが高く,映像制作現場で必要とされる非常に高解像度の流体映像を得るまでには...
[Conference] Video Retrieval based on User-Specified Appearance and Application to Animation Synthesis
Makoto Okabe, Yuta Kawate, Ken Anjyo, Rikio Onai
Proceedings of 19th International Conference on Multimedia Modeling, MMM 2013, Part II, pp. 110-120, Multimedia Retrieval and Management with Human Factors, Special Session Papers, Huangshan, China, 2013.1 PDF | DOI
In our research group, we investigate techniques for retrieving videos based on user-specified appearances. In this paper, we introduce two of our research activities.

First, we present a user interface for quickly and easily retrieving scenes of a desired appearance from videos. Given an input image, our system allows the user to sketch a transformation of an object inside the image, and then ...
[Invited Talk]Visual Simulation of Clouds - Inverse Design Approach -
Yoshinori Dobashi
Asian Conference on Design and Digital Engineering, Hokkaido Niseko, 2012.12
When creating synthetic images of outdoor scenes, clouds play important roles to enhance the realism. The research on the synthesis of realistic clouds has a long history and has attracted many researcher's interest. In this talk, I would present our researches on the visual simulation of clouds. Topics included in this talk are simulation and control of cloud motion using cellular automata/fluid ...
[Conference] Real-time rendering of animated hair under dynamic, low-frequency environmental lighting
Xiaoxiong Xing, Yoshinori Dobashi, Tsuyoshi Yamamoto, Yosuke Katsura, Ken Anjyo
Proceedings of Virtual Reality Continuum and its Application in Industry (VRCAI 2012), pp. 43-46, 2012.12 PDF | DOI
We present a fast algorithm for rendering animated hair under a dynamic lighting environment at interactive frame rates. We use spherical harmonics (SH) to represent the environmental lighting. Since SH functions are orthogonal, the environmental light is converted into an SH representation in real time. To compute hair shadows efficiently, the transmittances between a point on a hair strand and t...
[Conference] Feature-based interpolation for the interactive editing of shading effects
Munehiro Tada, Yoshinori Dobashi, Tsuyoshi Yamamoto
Proceedings of Virtual Reality Continuum and its Application in Industry (VRCAI 2012), pp. 47-50, 2012.12 PDF | DOI
In computer graphics, shading techniques play an important role when displaying realistic virtual objects. Although physically-based techniques can generate realistic results, it is often difficult to produce desired shading effects. Therefore, artists usually creates desired shading effects by manually placing many virtual light sources. However, this is not an easy task since it is difficult to ...
[Conference] Visual simulation of freezing ice with air bubbles
Takanori Nishino, Kei Iwasaki, Yoshinori Dobashi, Tomoyuki Nishita
SIGGRAPH ASIA 2012, Technical Brief, Article No. 1, 2012.11 PDF | DOI
Ice often contains small air bubbles that are dissolved air exhausted from water-ice interface. Depicting these air bubbles with various sizes enhances the realism of ice. This paper proposes a fast simulation method of freezing ice taking into account air bubbles. Our method introduces a physically-based calculation method of the sizes of air bubbles based on the freezing velocity and pressure. I...
[Poster] Keyframe Control of Cumulus Cloud Simulation
Katsutoshi Kusumoto, Yoshinori Dobashi, Tsuyoshi Yamamoto
ACM SIGGRAPH ASIA 2012 Poster Program, 2012.11
Clouds play an important role when creating realistic images of outdoor scenes. One of the most effective approaches for synthesizing realistic clouds is to simulate the cloud formation processes based on fluid dynamics. However, the resulting shapes of clouds depend on many simulation parameters. Therefore, it is difficult to adjust those parameters so that the clouds form the desired shapes. Thi...
[Poster] Rendering Animated Hair Under Dynamic Environmental Lighting
Xiaoxiong Xing, Yoshinori Dobashi, Tsuyoshi Yamamoto, Yosuke, Katsura, Ken Anjyo
ACM SIGGRAPH ASIA 2012 Poster Program, 2012.11
We present a fast algorithm for the interactive rendering of animated hair under a dynamic lighting environment. Previous methods use spherical radial basis functions (SRBF) for efficient evaluation of the rendering equation for hair [Ren et al. 2010]. However, this method is not suitable for dynamic lighting environments, since it requires a high computational cost to approximate environmental li...
[Journal] An inverse problem approach for automatically adjusting the parameters for rendering clouds using photographs
Yoshinori Dobashi, Wataru Iwasaki, Ayumi Ono, Tsuyoshi Yamamoto, Yonghao Yue, Tomoyuki Nishita
ACM Transactions on Graphics (TOG) - Proceedings of ACM SIGGRAPH Asia 2012, Volume 31 Issue 6, November 2012 Article No. 145 PDF | DOI
Clouds play an important role in creating realistic images of outdoor scenes. Many methods have therefore been proposed for displaying realistic clouds. However, the realism of the resulting images depends on many parameters used to render them and it is often difficult to adjust those parameters manually.
This paper proposes a method for addressing this problem by solving an inverse rendering p...
[Invited Talk] コンピューターグラフィックスの歴史と未来
土橋宜典
電子情報通信学会 スマートインフォメディアシステム研究会, 画像電子学会誌 第39巻, 第2号, pp. 215-219
世界最初のコンピューターグラフィックス(CG)システムが開発されてから約50年を経たこんにち, CGを用いた映像表現は日常的に目にするようになった. 本報告では, CG研究の発展の経緯をたどりながら, 基礎的研究から先端的研究までを概説する. CG研究の歴史は大別して, 創成期, 成長期, 成熟期に分類...
[Invited Talk] Mathematical models for computer facial animation
Ken Anjyo
Joint Workshop of IMS and IMI on Mathematics for Industry, Singapore, 2012.9
[Invited Talk] 数学がつなぐかたち-幾何学的な形状補間法-
鍛治静雄
CEDEC 2012, 2012.8
少数のキーフレーム(物体の形状データ)から、それらを補間する連続的なフレームデータを生成する技術は、フレーム補間とよばれ、アニメーション作成やインタラクティブな物体変形に使われています。
ここでは、特に局所的な形状をなるべく保ったままフレーム補間を行うアルゴリズムを、背...
[Conference] Extracting Fluid from a Video for Efficient Post-Production
Makoto Okabe, Ken Anjyo, Rikio Onai
ACM Digital Library, DigiPro '12 Proceedings of the Digital Production Symposium Pages 53-58, DOI
This paper proposes a method to extract fluids from a video that is captured outside a special studio. The method allows the designer to efficiently use the extracted fluids for the post-production.
[Conference] A Data-Driven Approach for Synthesizing High-Resolution Animation of Fire
Syuhei Sato, Takuya Morita, Yoshinori Dobashi, Tsuyoshi Yamamoto
ACM Digital Library, DigiPro '12 Proceedings of the Digital Production Symposium Pages 37-42, PDF | DOI
This work proposes a simple and efficient data-driven method for synthesizing high-resolution 3D animations of fire from low-resolution fluid simulations. The key concept behind our method is to use a pre-computed database of high-resolution velocity fields in order to produce small-scale details that are lost in low-resolution velocity fields.
[Conference] Mathematical Analysis on Affine Maps for 2D Shape Interpolation
Shizuo Kaji, Sampei Hirose, Shigehiro Sakata, Yoshihiro Mizoguchi, Ken Anjyo
EG and ACM Digital Libraries, Eurographics / ACM SIGGRAPH Symposium on Computer Animation (SCA2012), PDF| DOI
This paper gives a simple mathematical framework for 2D shape interpolation methods that preserve rigidity. An interpolation technique in this framework works for given the source and target 2D shapes, which are compatibly triangulated. Focusing on the local affine maps between the corresponding triangles, we describe a global transformation as a piecewise affine map. Several existing rigid shape ...
[Invited Talk] Geometrical and Statistical Issues in Computer Facial Animation
Ken Anjyo
Study Group Workshop 2012 (SGW 2012), Fukuoka, 2012.7
[Seminar] コンピュータグラフィックスと数学の接点
安生 健一, 土橋 宜典, 岡部 誠
第10回「計算機を用いた数学研究」GCOEセミナー 」概要
 日時- 7月20日(金)〜7月21日(土)
 会場- 京都大学理学部3号館 110講演室

コンピュータグラフィックス(CG)は様々な情報を可視化するという意味で、今やもっとも基本的な...
[Talk] コンピュータグラフィックスにおける顔と表情のモデル化
安生健一
CREST Workshop 生体形状モデリングと幾何学」概要
 日時- 2012年7月13日(金)14:00 - 17:30
 会場- 東京大学駒場キャンパス 大学院数理科学研究科第2講義室
[Poster] 勾配画像処理に基づく動画中の流体部分抽出
岡部誠, 安生健一, 尾内理紀夫
Visual Computing / グラフィクスと CAD 合同シンポジウム 2012, 2012.6
動画から爆発や煙等の半透明部分が広範囲に現れるような流体を抽出する手法を提案する。 通常、流体の背後には複雑な背景が存在するため、それと流体を分離する作業は時間と手間の掛かる作業となる。 そこで我々は全自動でこの問題を解決する手法を提案したい。 ここで動画を撮影したカメ...
[Article] 写実的レンダリング
岩崎慶
情報処理学会誌「情報処理」, Vol. 53, No. 6, pp. 556-561, 2012.5
[Article] 自然現象のビジュアルシミュレーション
土橋宜典
情報処理学会誌「情報処理」, Vol. 53, No. 6, pp. 562-547, 2012.5
コンピュータグラフィクスの新展開:自然現象のビジュアルシミュレーション
コンピュータグラフィクス(CG)において,水,炎,雲などの自然現象を表現するための手法は数...
[Article] ディジタルプロダクションにおける技術開発事例と今後の展開
安生健一, 四倉達夫
情報処理学会誌「情報処理」, Vol. 53, No. 6, pp. 595-599, 2012.5
コンピュータグラフィクスの新展開:ディジタルプロダクションにおける技術開発事例と今後の展開
今世紀に入ってからのデジタル映像の急速な需要拡大に伴い デジタルプロ...
[Invited Talk] Modeling, Rendering, and Simulating Clouds
Yoshinori Dobashi
Spring Conference on Computer Graphics, Slovakia, 2012.5
TBA
[Journal] Spacetime Expression Cloning for Blendshapes
Yeongho Seol, J. P. Lewis, Jaewoo Seo, Byungkuk Choi, Ken Anjyo, Junyong Noh
ACM Transactions on Graphics (TOG) , Volume 31 Issue 2, Article No. 14, 2012.4 DOI
The goal of a practical facial animation retargeting system is to reproduce the character of a source animation on a target face while providing room for additional creative control by the animator. This paper presents a novel direct method for facial animation retargeting. Our approach starts from the basic principle that the source and target movements should be similar. By interpreting movement...
[Invited Talk] Modeling, Rendering and Simulating Clouds
Yoshinori Dobashi
Studio Phones Seminar, Kobe
TBA
[Invited Talk] CGのための方程式、データベース、および演出
安生健一
日本計算工学会第1回S&V(Simulation & Visualization)研究会
第1回S&V(Simulation & Visualization)研究会」概要
 日時- 2012年3月2日(金) 13:30~17:00
 会場- 中央大学 後楽園キャンパス 新2号館2階2215
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