Details of a Researcher - Fujishiro, Issei

Papers - Fujishiro, Issei

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芸術科学フォーラム2012報告

FUJISHIRO Issei

DiVA（芸術科学会誌） 28 3-4 2012.04

Research paper (scientific journal), Single Work

計算美学のすゝめ

FUJISHIRO Issei

DiVA(Digital,Interactive and Visual Arts) (The Society for Art and Science) 28 2 - 2 2012.04

Research paper (scientific journal), Single Work

可視化による知識発見のライフサイクル管理とその流動応用評価

FUJISHIRO Issei, HAYASE Toshiyuki, TAKESHIMA Yuriko

平成22年度共同利用・共同研究拠点「流体科学研究拠点」活動報告書 (東北大学流体科学研究所) ( J10037 ) 79-80 2011.10

Research paper (other academic), Single Work

Previewing volume decomposition through optimal viewpoints

TAKAHASHI Shigeo, FUJISHIRO Issei, TAKESHIMA Yuriko, BI Chongke

Scientific Visualization: Interactions, Features, Metaphors, Dagstuhl Follow-Ups (Dagstuhl Publishing, Germany) 2 Chapter 23 (346-359) 2011.10

Research paper (conference, symposium, etc.), Joint Work, Accepted, ISSN 1868-8977

Understanding a volume dataset through a 2D display is a complex task because it usually contains multi-layered inner structures that inevitably cause undesirable overlaps when projected onto the display. This requires us to identify feature subvolumes embedded in the given volume
and then visualize them on the display so that we can clarify their relative positions. This article therefore introduces a new feature-driven approach to previewing volumes that respects both the 3D nested structures of the feature subvolumes and their 2D arrangement in the projection by minimizing their occlusions. The associated process begins with tracking the topological transitions of isosurfaces with respect to the scalar field, in order to decompose the given volume dataset into feature components called interval volumes while extracting their nested structures. The volume dataset is then projected from the optimal viewpoint that archives the best balanced
visibility of the decomposed components. The position of the optimal viewpoint is updated each time when we peel off an outer component with our interface by calculating the sum of the viewpoint optimality values for the remaining components. Several previewing examples are
demonstrated to illustrate that the present approach can offer an effective means of traversing volumetric inner structures both in an interactive and automatic fashion with the interface.

SPH-based method for interactive flame simulation - Implementation on CPU and GPU

MABUCHI Satoshi, OHNO Yoshio, FUJISHIRO Issei

Proceedings of ASIAGRAPH2011 (Virtual Reality Society of Japan) 41-46 2011.10

Research paper (conference, symposium, etc.), Joint Work

In this paper, we propose a novel, particle-based flame simulation method, which relies on SPH to simulate the dynamics of flames by introducing a buoyancy term as an external force to the Navier-Stokes equations. The buoyancy term is directly affected by heat generated from a simple chemical reaction model. For efficiency, we adaptively re-sample particles around a flame. We demonstrate that it is possible to execute three-dimensional flame simulations in real-time for typical cases including transition from initial to stable states, and one-way coupling with solid. Our method offers reasonable results on CPU, while more realistic results can be obtained using GPGPU.

Measurement-integrated simulation and visualization of Karman vortex streets in Hybrid Wind Tunnel

TAKESHIMA Yuriko, FUJISHIRO Issei, TAKAHASHI Shigeo, HAYASE Toshiyuki

Proceedings of ASIAGRAPH2011 (Virtual Reality Society of Japan) 35-40 2011.10

Research paper (conference, symposium, etc.), Joint Work

We have developed a hybrid wind tunnel, where 2D measurement-integrated (MI) simulation, which utilizes actual data acquired from real air flow behind a square cylinder, plays an important role in improving the accuracy of its numerical analysis. The wind tunnel requires an accompanying visual analysis tool with which we can effectively peer into the relationships between the actual and simulated flow fields. In this paper, we attempt to exploit the augmented reality-style display technique to that end. The basic idea is to instantaneously superimpose the computationally-visualized MI simulated pressure field onto the actual flow velocity structure physically-visualized with oil mist-traced streak lines. Space registration of these two visual sources is rather straight-forward since the fixed cylinder of the wind tunnel is easily identified, whereas visualizing the MI simulated pressure field can be characterized with its sophisticated scheme based on differential topology. Considering the facts that vortex centers are located at local minima in the pressure field, and each minimum is surrounded by a derived topological feature called ravine cycle, we can colorize the field adaptively and keep track of Karman vortex streets robustly, regardless of drastic change in the Reynolds number of the flow field.

SPH-based Real-time Flame Simulation

MABUCHI Satoshi, FUJISHIRO Issei, OHNO Yoshio

Journal of IPSJ (IPSJ) 52 ( 10 ) 2965-2972 2011.10

Research paper (scientific journal), Joint Work, Accepted, ISSN 1882-7764

In this paper, we propose a novel particle-based flame simulation method, which relies on SPH to simulate the dynamics of flame by introducing a buoyancy term as an external force to Navier-Stokes equation. The buoyancy term is directly affected by heat generated from a simple chemical reaction model. Good interchangeability allows us to easily couple our method with existing SPH source codes. For efficient execution, we adaptively re-sample particles around flame. We demonstrate three-dimensional simulations in real-time for typical cases including transition from initial to stable states, and one-way coupling with solid.

GPU-Based Adaptive Visualization for Particle Systems

ODAGAWA Masato, TAKESHIMA Yuriko, FUJISHIRO Issei, KIKUGAWA Gota, OHARA Taku

Transactions of the JSME (in Japanese) (JSME) 77 ( 781 ) 1767-1778 2011.09

Research paper (scientific journal), Joint Work, Accepted

When visualizing large-scale particle systems, it is difficult to maintain adequate framerates because we have to render dynamic scenes with a large number of small spheres. For the control of trade-offs between the overall image quality and total rendering speed, we propose a new rendering scheme which uses a fast method based on shaded texture mapping and a high-quality implicit surface method in a combined way. The shaded texture mapping, which generates a pseudo-texture through alpha-blending a proper portion of template texture for shade and highlight onto a base spherical texture, can render a particle faster than the implicit surface method. However, a weakness of the texture mapping lies in its poor shading quality. In contrast, the implicit surface method is accurate enough for analyzing particle systems visually. Actual method to render each particle is decided according to the viewing distance; the high-quality method is chosen only when the distance is smaller than a threshold, to allow the user to observe the region of interest closely. We use a molecular dynamics simulation dataset to evaluate the effectiveness of our scheme empirically. In addition to this, we also consider the extensibility of our scheme in terms of framerate stability, scalability, and expressiveness.

Particle-Based Real-Time Flame Rendering

MABUCHI Satoshi, FUJISHIRO Issei, OHNO Yoshio

The Journal of the Institute of Image Electronics Engineers of Japan (IIEEJ) 40 ( 4 ) 541-548 2011.07

Research paper (scientific journal), Joint Work, Accepted, ISSN 0285-9831

In this paper, we propose a particle-based method for real-time flame rendering. In the field of visualization, particle-based volume rendering has been introduced for the purpose of previewing. Our method is a reasonably-simplified version of the particle-based volume rendering. Compared with previous flame rendering methods, both detail representation and controllability are sufficiently improved. In addition to this, it is easily implemented using standard APIs, and its fast enough rendering speed allows us to adjust environmental settings on the fly. Moreover, our method requires a few standard parameters as particle attributes, and thus it would be used in conjunction with existing particle simulators.

Design of Surface Descriptor for Rendering Snow-Covered Terrain

NAKATANI Ayaka, FUJISHIRO Issei, OHNO Yoshio

The Journal of the Society for Art and Science (The Society for Art and Science) 10 ( 2 ) 79-86 2011.06

Research paper (scientific journal), Joint Work, Accepted, ISSN 1347-2267

Seasonally-transient contrast between snow and mountain surfaces makes a big appeal to every viewer. Generally, when deciding how much snow covers the mountain, we need to take many climatological factors into account, and it is likely to complicate the rendering process. In this paper, we present a phenomenological model which easily depicts snow-covered mountains. Our method relies on our own surface descriptor, which is based primarily on Tangent Sphere Accessibility of smoothed height field, and also considers geometric features like azimuth direction and altitudes to a limited extent. The feasibility of the proposed method is illustrated through application to a real height map dataset.

Interpolating 3D diffusion tensors in 2D planar domain by locating degenerate lines

BI Chongke, TAKAHASHI Shigeo, FUJISHIRO Issei

6th International Symposium, ISVC 2010, Las Vegas, NV, USA, November 29-December 1, 2010, Proceedings, Part I (Lecture Notes in Computer Science) (Springer-Verlag) 6453 328-337 2010.11

Research paper (conference, symposium, etc.), Joint Work, Accepted

Interpolating diffusion tensor fields is a key technique to visualize the continuous behaviors of biological tissues such as nerves and muscle fibers. However, this has been still a challenging task due to the difficulty to handle possible degeneracy, which means the rotational inconsistency caused by degenerate points. This paper presents an approach to interpolating 3D diffusion tensors in 2D planar domains by aggressively locating the possible degeneracy while fully respecting the underlying transition of tensor anisotropy. The primary idea behind
this approach is to identify the degeneracy using minimum spanning tree-based clustering algorithm, and resolve the degeneracy by optimizing the associated rotational
transformations. Degenerate lines are generated in this process to retain the smooth transitions of anisotropic features. Comparisons with existing interpolation
schemes will be also provided to demonstrate the technical advantages of the proposed approach.

山岳形状における積雪量を決定するサーフェス記述子の提案

NAKATANI Ayaka, FUJISHIRO Issei, OHNO Yoshio

第26回NICOGRAPH論文コンテスト (芸術科学会) 2010.09

Research paper (conference, symposium, etc.), Joint Work

本論文では，山岳形状における積雪の様子を再現する現象学的モデルを提案する．ここでは，積雪の時間変化や山肌とのコントラストなどの美しさを手軽に表現し，しかも制御可能にすることを目的としている．山肌における積雪の度合いを決めるためには，その場所での気候や気象，雪の密度・粘性・固さなど，一般的に現実世界の多くの物理的ファクタを考慮する必要があるが，本手法では独自のサーフェス記述子を介することで積雪の現象学的再現を試みる．そのサーフェス記述子は，平滑化された高さ場におけるTangent Sphere Accessibility をベースに，方角や高度などの幾何学的条件を限定的に考慮している．本論文ではさらに，実際の標高データを用いた山岳形状に適用し，提案手法の視覚的効果を検証する．

大野義夫先生（慶應義塾大学）第9回CG Japan Awardを受賞

FUJISHIRO Issei

芸術科学会誌 (芸術科学会) ( 21 ) 10-11 2010.08

Research paper (scientific journal), Single Work

Perceptually-guided design of nonperspectives through pictorial depth cues

YOSHIDA Kenichi, TAKAHASHI Shigeo, ONO Hiroaki, FUJISHIRO Issei, OKADA Masato

Proceedings of the Seventh International Conference on Computer Graphics, Imaging and Visualization 173-178 2010.08

Research paper (conference, symposium, etc.), Joint Work, Accepted

Introducing distortions into perspective views is a popular
technique to direct our visual attention to specific objects, as seen in hand-drawn illustrations and cartoon animations. This type of image expression, called nonperspective projection, is feasible in visual communication, because the human visual system can reconstruct the target three-dimensional (3D) scene correctly provided that the corresponding image distortions are within a certain perceptual tolerance. In this paper, we develop a perceptual approach to guiding the
design of such nonperspective images by referring to the 3D
perception induced by pictorial depth cues. We formulate an
acceptable tolerance by investigating how we perceive image
distortion according to the change in the configuration of
depth cues. The obtained formulation is then incorporated
into our new algorithm, with which we can automatically
control plausible image deformation by simply modifying
the positions and sizes of specific objects in a scene.

可視化による知識発見のライフサイクル管理とその流動応用評価

FUJISHIRO Issei, HAYASE Toshiyuki, OOBAYASHI Shigeru, TAKESHIMA Yuriko

平成21年度公募共同研究報告書 (東北大学流体科学研究所) ( J09038 ) 79-80 2010.08

Research paper (other academic), Single Work

自己組織化単分子膜のための粒子配置設計支援システム

TAKESHIMA Yuriko, NIIZAKA Takuma, KIKUGAWA Gota, OHARA Taku, FUJISHIRO Issei

第38回可視化情報シンポジウム講演論文集 (可視化情報学会) 30 ( 1 ) 277 - 280 2010.07

Research paper (conference, symposium, etc.), Joint Work

Topologically-based haptization and visualization of wake turbulence datasets

TAKESHIMA Yuriko, FUJISHIRO Issei, TAKAHASHI Shigeo, OOBAYASHI Shigeru

DVD Proceedings of Image Electronics and Visual Computng 2010 (Institute of Image Electronics Engineers of Japan) 2010.03

Research paper (conference, symposium, etc.), Joint Work, Accepted