2014 Fiscal Year

International Academic Journals

Issei Fujishiro
Computational Journalism: Promising scenarios of big data visualization
Transactions on Image Electronics and Visual Computing (invited paper), Vol. 2, No. 2, pp. 134-137, December 2014
A nascent framework, called computational journalism, is intended to take the concept of accountability into account so as to suggest a promising direction of computer visualization research and development toward the era of big data. In this article, we strive to identify six central features inherent to computational journalism | super real-time computability, spatiotemporal completeness, visualization provenance management, first-person perspective preservation, audience-driven reporting, and perceptually-allowable deformation | through re-examining practical results obtained in our recent visualization studies. Each of these features indeed contributes to breaking the curse of traditional media, and seeking out the ideal form of journalism.

Tetsuya Takahashi, Yoshinori Dobashi, Issei Fujishiro, Tomoyuki Nishita
Volume preserving viscoelastic fluids with large deformations using position-based velocity corrections
The Visual Computer, Vol. 32, No. 1, pp. 57–66, January 2016 (first online: December 6, 2014) [DOI: 10.1007/s00371-014-1055-x]
We propose a particle-based hybrid method for simulating volume preserving viscoelastic fluids with large deformations. Our method combines smoothed particle hydrodynamics (SPH) and position-based dynamics (PBD) to approximate the dynamics of viscoelastic fluids. While preserving their volumes using SPH, we exploit an idea of PBD and correct particle velocities for viscoelastic effects not to negatively affect volume preservation of materials. To correct particle velocities and simulate viscoelastic fluids, we use connections between particles which are adaptively generated and deleted based on the positional relations of the particles. Additionally, we weaken the effect of velocity corrections to address plastic deformations of materials. For one-way and two-way fluid-solid coupling, we incorporate solid boundary particles into our algorithm. Several examples demonstrate that our hybrid method can sufficiently preserve fluid volumes and robustly and plausibly generate a variety of viscoelastic behaviors, such as splitting and merging, large deformations, and Barus effect.

Ken Nagao, Issei Fujishiro
Mood-Learning Public Display: Adapting content design evolutionarily through viewers’ involuntary gestures and movements
IEICE Transactions on Information and Systems, Vol. E97-D, No. 8, pp. 1991-1999, August 2014 [DOI: 10.1587/transinf.E97.D.1991]
Due to the recent development of underlying hardware technology and improvement in installing environments, public display has been becoming more common and attracting more attention as a new type of signage. Any signage is required to make its content more attractive to its viewers by evaluating the current attractiveness on the fly, in order to deliver the message from the sender more effectively. However, most previous methods for public display require time to reflect the viewers’ evaluations. In this paper, we present a novel system, called Mood-Learning Public Display, which automatically adapts its content design. This system utilizes viewers’ involuntary behaviors as a sign of evaluation to make the content design more adapted to local viewers’ tastes evolutionarily on site. The system removes the current gap between viewers’ expectations and the content actually displayed on the display, and makes efficient mutual transmission of information between the cyberworld and the reality.

Tetsuya Takahashi, Tomoyuki Nishita, Issei Fujishiro
Fast simulation of viscous fluids with elasticity and thermal conductivity using position-based dynamics
Computers & Graphics, Vol. 43, pp. 21-30, July 2014 [DOI: 10.1016/j.cag.2014.06.002]
In this paper, we propose a novel particle-based Lagrangian method for efficiently simulating viscous fluids by adopting position-based constraints. Our method uses the geometric configuration of particles for the positional constraints to approximate the dynamics of viscous fluids using position-based dynamics; thus the method can plausibly generate their motions while allowing for the use of much larger time steps than those previously adopted in the viscous fluid simulations. We also propose an associated boundary-handling scheme for position-based fluids to precisely specify boundary conditions for the constraints. Additionally, we reproduce elastic deformations of materials by controlling the constraints and incorporate thermal conduction into our framework to simulate resultant changes in particle properties and phase transition in the materials. By adjusting parameters, our method can encompass complex motions of fluids with different properties in a unified framework. Several examples demonstrate the effectiveness as well as versatility of our method.

International Conference Proceedings

Kazuhide Ueda, Issei Fujishiro
Splashing liquids with ambient gas pressure
Proceedings of ACM SIGGRAPH Asia 2014 Technical Briefs, Shenzhen (China), December 2014 [DOI: 10.1145/2669024.2669036]
Splashing occurs when a liquid drop hits the solid or fluid surface at a high velocity. The drop after the impact spreads and forms a corona with a thickened rim, which first develops annular undulations and then breaks into secondary droplets. We have many chances to see splashes in our daily life, e.g., milk crown, splashing paint, and raindrops falling onto a pool, whose characteristics of deformation have a significant impact on the visual reality of the phenomena. Many experimental studies have been conducted to find criteria on when splashing would occur, but the physical mechanisms of splashing are still not completely understood. It was only recently discovered that ambient gas pressure is a principal factor for creating such a splash. In this paper, therefore, we newly incorporate the ambient gas pressure effect into the Navier-Stokes equations through SPH fluid simulation for representing more accurate splashing dynamics. Our experiments demonstrated that the new approach requires very little additional computing cost to capture realistic liquid behaviors like fingering, which have not previously been attained by SPH nor most schemes for fluid simulation.

Takami Yamamoto, Masanori Nakayama, Rui Katsura, Akira Sakamoto, Issei Fujishiro
Development of a pants pattern design system based on 3D human body measurement data analysis
in Proceedings of the 4th IIEEJ International Workshop on Image Electronics and Visual Computing Workshop 2014, Vol.4B-2, Koh Samui (Thailand), October 2014
In this paper, we propose a pants pattern design covering its highly precise design to pattern making by analyzing human body measurement data acquired with a 3D scanner. This system is characterized by: (1) being able to analyze data required for the design of pants patterns using an improved 3D human body measurement analysis application, and (2) being provided with automatic pants drafting functions installed in an apparel CAD system using 3D human body measurement data. As a result, individual 3D human body measurement data can be analyzed both accurately and rapidly, thereby enabling pants patterns that are comfortable and properly fit the physique of the wearer to be obtained in a short period of time.

Koto Nohno, Hsiang-Yun Wu, Kazuho Watanabe, Shigeo Takahashi, Issei Fujishiro
Spectral-based contractible parallel coordinates
Proceedings of iV2014, Paris (France), pp. 7-12, July 2014 [DOI: 10.1109/IV.2014.60]
This paper presents a method of alleviating such visual clutter by contracting multiple axes through the analysis of correlation between every pair of variables. In this method, we first construct a graph by connecting axis nodes with an edge weighted by data correlation between the corresponding pair of dimensions, and then reorder the multiple axes by projecting the nodes onto the primary axis obtained through the spectral graph analysis. This allows us to compose a dendrogram tree by recursively merging a pair of the closest axes one by one. Our visualization platform helps the visual interpretation of such axis contraction by plotting the principal component of each data sample along the composite axis. Smooth animation of the associated axis contraction and expansion has also been implemented to enhance the visual readability of behavior inherent in the given high-dimensional datasets.

Yuriko Takeshima, Takashi Misaka, Shigeru Obayashi, Frank Holz’apfel, Hiroshi Kato, Shigeo Takahashi, Issei Fujishiro
Topological approach to multisensory realization of wake turbulence
Proceedings of Aviation 2014, pp. 7-12, Atlanta (United States), June 2014 [DOI: 10.2514/6.2014-2335]
It is important to analyze the process of wake turbulence collapse to avoid serious accidents. In this study, we propose a topology-based multisensory realization method that allows observers to comprehend the behavior of wake turbulence phenomena in more intuitive manner. We propose the use of adaptive visual transfer functions as well as haptic transfer functions with three degrees of freedom to produce three-dimensional forces, which allow the identification of the location and strength of a target vortex. We evaluate the effectiveness of our method using a time-varying three-dimensional wake turbulence dataset.

Tetsuya Takahashi, Issei Fujishiro, Tomoyuki Nishita
A velocity correcting method for volume preserving viscoelastic fluids
Proceedings of CG International 2014, Sydney (Australia), June 2014
We propose a new particle-based method for simulating viscoelastic fluids which preserve their volumes. Our method achieves the volume preservation by enforcing the incompressibility of fluid, while correcting particle velocities to approximate the dynamics of viscoelastic fluids without disturbing computations for the incompressible ow. We offer three schemes for correcting particle velocities. The first scheme employs Shape Matching proposed by Müeller et al. to derive appropriate transformations of particle sets. The second computes attraction forces on the basis of Hooke’s law to restrict particle motions. The third utilizes Position-Based Dynamics to restore the original relations of particle positions. The first scheme enables smooth transfers of deformation waves, the second is intuitive and simple, and the third is easy to tune parameters. We demonstrate that our method can preserve fluid volumes while generating plausible viscoelastic motions.

Tetsuya Takahashi, Issei Fujishiro, Tomoyuki Nishita
Visual simulation of compressible snow with friction and cohesion
Proceedings of NICOGRAPH International 2014, pp. 35-42, Gotland (Sweden), June 2014
Recent advances in physically-based simulation have made it possible to simulate various kinds of natural phenomena. However, characteristic behavior of accumulated snow while being compressed due to pressure has been insufficiently simulated merely with a height field approximation. In this paper, we propose a new method for simulating compressible snow by approximating snow as a set of porous snow particles. We introduce a new parameter called durability for each porous snow particle, which represents the rate of undamaged snow structures. The compression of accumulated snow is achieved by absorbing the impact from solids on the snow by taking the durability of snow particles into account. In addition to the compressibility, we incorporate friction and cohesion into our simulation framework to represent various effects of accumulated snow. For enhanced visual reality, fine scale simulations are performed as a post-processing. Several examples demonstrate the versatility of our method.

International Conference Posters (Peer-Reviewed)

Yasunari Ikeda, Issei Fujishiro
An object space approach to shadowing for hair-shaped objects
in Proceedings of ACM SIGGRAPH 2014 Posters, Vancouver (Canada), December 2014 [DOI: 10.1145/2614217.2633392]
Three-dimensional objects can be rendered more realistically with their shadows. Commonly-used shadowing methods based on textures with depth values are unfortunately likely to cause aliasing, which is usually ameliorated by such image-space post-processing as neighboring pixel averaging or variance-based smoothing. However, spatial/temporal aliasing can still be observed in pieces and films of work when bundles of thin strands like human hairs are targeted. We can generate sharp shadows even from such intricate shapes if we suitably move their vertices or expand their mesh at the sacrifice of extra computation. Our method attempts to tackle this type of aliasing problem in a simpler manner by generating anti-aliased shadow splats in the object space.

Oral Presentation

Issei Fujishiro
Contractible parallel coordinates for sparse modeling
Dagstuhl Seminar on Scientific Visualization 2014 , Schloss Dagstuhl, Waderm, 2014 年 6月