Papers by Yuriko Takeshima
Guidelines for LoD Control in Volume Visualization
The Journal of the Institute of Image Electronics Engineers of Japan, 2008
TVML (TV program Making Language) is a technology capable of obtaining TV (television)-programme-... more TVML (TV program Making Language) is a technology capable of obtaining TV (television)-programme-like Computer Graphics (CG) animation by writing text script. We have originally developed TVML and ...
Understanding a volume dataset through a 2D display is a complex task because it usually contains... more 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. T...
Journal of Composites Science, 2021
Discontinuous carbon fiber-carbon matrix composites dispersed Si/SiC matrix composites have compl... more Discontinuous carbon fiber-carbon matrix composites dispersed Si/SiC matrix composites have complicated microstructures that consist of four phases (C/C, Si, SiC, and C/SiC). The crack stability significantly depends on their geometrical arrangement. Nondestructive evaluation is needed to maintain the components in their safe condition. Although several nondestructive evaluation methods such as the Eddy current have been developed, any set of them is still inadequate in order to cover all of the scales and aspects that (C/C)/Si/SiC composites comprise. We propose a new method for nondestructive evaluation using vibration/resonance modes and deep learning. The assumed resolution is mm-order (approx. 1–10 mm), which laser vibrometers are generally capable of handling sufficiently. We utilize deep neural networks called convolutional auto-encoders for inferring damaged areas from vibration modes, which is a so-called inverse problem and infeasible to solve numerically in most cases. We...
Scientific Visualization Conference (dagstuhl '97), 1997
Journal of the Visualization Society of Japan, 2016
608 Topology-Based Illumination Design for Time-Varying Volume Rendering
The proceedings of the JSME annual meeting, 2008
Journal of the Visualization Society of Japan, 2005
Isosurfacing is one of the most useful visualization technique. Although isosurfacing can visuali... more Isosurfacing is one of the most useful visualization technique. Although isosurfacing can visualize a given volume dataset faster than other visualization techniques, more accelerated isosurface extraction algorithm is required for large-scale and complex dataset. This paper represents an accelerated isosurface extraction algorithm using a critical point graph. Sevelal datasets such as analytic dataset are used to prove the temporal efficiency of the presented extraction algorithm compared with a well-known isosurfacing algorithm called Marching Cubes.
Journal of the Visualization Society of Japan, 2008
Journal of the Visualization Society of Japan, 2007
Locating an optimal light source is an important task for image synthesis because it influences t... more Locating an optimal light source is an important task for image synthesis because it influences the spatial perception of the observers. Several methods have been proposed, that search for the optimal location of light sources for 3D surfaces, but none has been done for volumes. This paper presents a new method for finding an optimal location of a single parallel light source for volumetric ray-casting. The method computes the entropy of brightness distribution of representative isosurfaces. The method then utilizes the opacity transfer function to assign a distinct weight to each of the values of isosurface illumination entropy to evaluate the plausible illuminating entropy for the volume. The light with the maximum entropy value allows the observers to realize the volume features with enriched 3D visual cues.
Journal of the Visualization Society of Japan, 2005
This paper presents the design of multi-dimensional transfer functions which take into account th... more This paper presents the design of multi-dimensional transfer functions which take into account the nested structures of evolving isosurfaces in a given volume dataset . The effectiveness of the resultant topological transfer functions is proven empirically through an application to a simulated dataset for implosion phenomena in laser fusion.
The Journal of the Institute of Image Information and Television Engineers, 2002
Analytic, simulated, scanned datasets were used to evaluate two representative data-centric metho... more Analytic, simulated, scanned datasets were used to evaluate two representative data-centric methods for designing transfer functions (TFs), which are a key factor determining the quality of volume rendered images. They map the physical fields of a given volume dataset to the optical properties, such as color and opacity. Designing proper TFs is difficult because they depend on both the context of the target volume dataset and the purpose of the visual exploration. A system called "Ivory" was developed to assist in the design of TFs. With it, a better TF can be composed so as to inherit different features from two original TFs.
Journal of the Visualization Society of Japan, 2007
When visualizing volume datasets, we frequently encounter a problem that optical occlusion makes ... more When visualizing volume datasets, we frequently encounter a problem that optical occlusion makes it hard to grasp the spatial location (esp. depth) of target features precisely. A haptization is well-known as an effective solution to this problem. However, insufficient haptizations do not lead to a complete resolution, but also may give wrong information to users. It is important to design appropriate haptic transfer functions (HTFs) tailored specifically to a given dataset. Our primary focus in this study is placed on 3D diffusion tensors. Due to the developments of related scanning devices, the analysis of diffusion tensors has recently attracted much attention from related researchers. In this paper, we strive to present a 6DOF HTF, which utilizes 3D forces and 3D torques sophisticatedly to convey the core information of diffusion tensor values. The effectiveness of the 6DOF HTF using a PHANToM Premium 3.0 is proven through user evaluation experiments.
TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B, 2011
When visualizing large-scale particle systems, it is difficult to maintain adequate framerates be... more 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.
Journal of the Visualization Society of Japan, 2005
T-Map: A Topological Approach to Visual Exploration of Time-Varying Volume Data
Lecture Notes in Computer Science
The rapid advance in high performance computing and measurement technologies has recently made it... more The rapid advance in high performance computing and measurement technologies has recently made it possible to produce a stupendous amount of time-varying volume datasets in a variety of disciplines. However, there exist a few known visual exploration tools that allow us to investigate the core of their complex dynamics effectively. In this paper, our previous approach to topological volume skeletonization is extended to capture the topological features of large-scale time-varying volume datasets. A visual exploration tool, termed T-map, is presented, where pixel-oriented information visualization techniques are deployed so that the user can identify partial 4D spatiotemporal domains with characteristic changes in a topological sense, prior to detailed and comprehensible volume visualization. A case study with datasets from atomic collision research is performed to illustrate the feasibility of the proposed tool.
Numerical Analysis of Clear Air Turbulence by Using Large Eddy Simulation Coupled with a Meteorological Model
51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, 2013
5Computational fluid dynamics (CFD) simulation of clear air turbulence (CAT) is conducted by coup... more 5Computational fluid dynamics (CFD) simulation of clear air turbulence (CAT) is conducted by coupling numerical weather simulation and large eddy simulation (LES). Initial and boundary conditions of the LES are defined base on Japan Meteorological Agency’s Non-Hydrostatic Model (JMA-NHM) with three levels of downscaling. The target location and time of JMA-NHM are determined by 40 cases of the flight data that encountered CAT. With a goal of identifying the important turbulence indices, selforganizing map (SOM) is applied to the results of CFD simulation. The results of the SOM showed that CAT can be categorized into two types. One is CAT associated with Richardson number (Ri) and Scorer parameter (SP), which indicate atmospheric stability, and vertical wind shear (VWS), vertical gradient of horizontal wind (dVdz), energy dissipation rate (EDR) and wind direction (WD). Another is CAT cannot be detected by existing indices. Therefore, visualization of flow and turbulence index fields as well as information visualization were conducted for the latter type of CAT. In the result, we found that the unpredictable CAT is associated with the inflection point of vertical profiles concerning wind speed and direction.
Mathematics and Visualization
Proceedings. Visualization '97 (Cat. No. 97CB36155)
Modular Visualization Environments (MVEs) have recently been regarded as the de facto standard fo... more Modular Visualization Environments (MVEs) have recently been regarded as the de facto standard for scientific data visualization, mainly due to adoption of visual programming style, reusability, and extendability. However, since scientists and engineers as the MVE principal user are not always familiar with how to map numerical data to proper graphical primitives, the set of built-in modules is not fully used to construct necessary application networks. Therefore, a certain mechanism needs to be incorporated into MVEs, which makes use of heuristics and expertise of visualization specialists (visineers), and which supports the user in designing his/her applications with MVEs. The Wehrend' s goal-oriented taxonomy of visualization techniques is adopted as the basic philosophy to develop a system, called GADGET, for application design guidance for MVEs. The GADGET system interactively helps the user design appropriate applications according to the specific visualization goals, temporal efficiency versus accuracy requirements, and such properties as dimension and mesh type of a given target dataset. Also the GAD-GET system is capable of assisting the user in customizing a prototype modular network for his/her desired applications by showing execution examples involving datasets of the same type. This paper provides an overview of the GADGET guidance mechanism and system architecture, with an emphasis on its knowledge base design. Sample data visualization problems are used to demonstrate the usefulness of the GADGET system.
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Papers by Yuriko Takeshima