Fumiaki Araki

MovieMaker: a parallel movie-making software for large-scale simulations

We have developed a parallel rendering software for scientific visualization of large-scale, three-dimensional, time development simulations. The goal of this software, MovieMaker, is to generate a movie, or a series of visualization images from one terabyte-scale data set within one night (or less than 12 h). The isorontouring, volume rendering, and streamlines are implemented. MovieMaker is a parallel program for the shared memory architecture with dynamic load balancing and overlapped disk I/O.

A New Approach to Ocean Eddy Detection, Tracking, and Event Visualization Application to the Northwest Pacific Ocean

High-resolution ocean general circulation models have advanced the numerical study of ocean eddies. To gain an understanding of ocean eddies from the large volume of data produced by simulations, visualizing just the distribution of eddies at each time step is insufficient; time- variations in eddy events and phenomena must also be considered. However, existing methods cannot accurately detect and track eddy events such as amalgamation and bifurcation. In this study, we propose a new approach for eddy detection, tracking, and event visualization based on an eddy classification system. The proposed method detects streams and currents in addition to eddies, and it classifies detected eddies into several categories using the additional stream and current information. By tracking how the classified eddies vary over time, it is possible to detect events such as eddy amalgamation and bifurcation as well as the interaction between eddies and ocean currents. We visualize the detected eddies and events in a time series of images (or animation), enabling us to gain an intuitive understanding of a region of interest hidden in a high-resolution data set.

Multiple Scatter Plots Based Multi-dimensional Transfer Function for Visualizing Ocean Simulation Data

This study proposes a multiple scatter plots based multi-dimensional transfer function for visualizing characteristic structures from ocean simulation data. In the proposed method, characteristic features are manually extracted in a couple of 2-dimensional scatter plots using visual effect and empirical judgment based on user’s existing knowledge. Extracted structures in each 2-variable space are assigned to other color dimensions such as Hue, Saturation and Brightness for the purposes of feature specification and classification. We applied the proposed method to high-resolution ocean data in two different regions. Ocean currents are intuitively extracted in multiple scatter plots and represented using multi-dimensional transfer functions.

Symposium on visualization in high-performance computing at SIGGRAPH Asia 2015

The symposium on visualization in high-performance computing (VHPC) was held in conjunction with ACM SIGGRAPH Asia 2015 in Kobe, Japan, between 2 and 4 November, 2015. The number of participants was over 260 from Japan and a few other countries. The state-of-the-arts in many aspects of scientific visualization, information visualization and visual analytics were presented and discussed. In total, 45 papers were submitted from five countries. After a rigorous peer review process where each paper was reviewed by at least two reviewers, 15 full papers were selected for presentation. Three speakers were invited by VHPC. As a keynote presentation, Prof. Kwan-Liu Ma from the University of California, Davis (UC Davis), USA, gave a talk titled ‘‘Visualization and high performance computing’’. Dr. E. Wes Bethel from Lawrence Berkeley National Laboratory (LBNL), USA, presented his talk titled ‘‘HPC visualization and analysis at the exascale: big headaches, big opportunities’’ as an invited talk. Dr. Hirofumi Seo from SCIEMENT Inc., Japan, gave a presentation of his visualization works in medical front as a special talk. In addition, VHPC featured two tutorials and a visualization contest. In the final session, VHPC also featured a panel discussion, including six panelists on the unsolved visualization research problems. In the symposium, 15 papers were selected for presentation from 45 submissions. Among those presentations, four papers were finally accepted for publication by the standard peer review process of Journal of Visualization (JOV). We wish to thank the editors and reviewers of JOV for making it possible to publish this special feature from VHPC. We also thank the authors for their careful and insightful work and cooperation in the preparation of the revised papers. It will be our pleasure if readers appreciate the hot topics in visualization research as a result of this special feature. We would like to express our sincere thanks to the staff at Springer-Verlag for their kind support.

Application of Visual Analytics to Ocean Science: Case Studies

High resolution OGCM (Ocean General Circulation Model) reproduces various types of complex structures defined by multivariable such as warm/cold current or high/low density water mass. In order to understand such characteristic features, it is necessary to visualize and explore multivariable dataset. Therefore, we applied visual analytics, especially multi-dimensional transfer function and visual feature exploration, to represent characteristic ocean structures. Our case studies show that visual analytics is effective for understanding ocean simulation dataset.

Abstract: Visualization for High-Resolution Ocean General Circulation Model via Multi-dimensional Transfer Function and Multivariate Analysis

Ocean currents and vortices play an important role in transferring heat, salt or carbon as well as atmospheric circulation. With advances in supercomputing technology, high-resolution large-scale simulation study has been focused in the field of ocean science. However, it is difficult to intuitively understand characteristic features defined as multivariable hiding in the high-resolution dataset. In order to obtain scientific knowledge from large-scale simulation data, it is important to effectively extract and to efficiently express the characteristic feature. The aim of this study is how to efficiently extract and how to effectively visualize ocean currents which affect the heat transportation. In this research, new multi-dimensional transfer function to emphasis the ocean currents and vortices is proposed. Furthermore, multivariate analyses to extract such features are developed. This presentation describes the methodologies and experimental results of these methods. Evaluation of visualization results and feedback to the parameter optimization will be also reported.

Visualization analysis of large-scale three-dimensional scalar data of ocean simulation

We visualize the data set of the hind-cast experiment of OFES (Sasaki et al., 2004). The horizontal resolution and the number of vertical levels are 0.1 degree and 54, respectively. Total data size of simulated sea temperature is 3600 × 1500 × 54 Grids × 4 Bytes × 6575 Snapshots = 7.7 Tera Bytes. In our visualization results, all of the simulated events are displayed by ray-casting volume rendering in the global view like Fig. 1, which represents the IOD and El Niño simultaneously without losing the resolution of original out put data. These sets of the pictures through 54 years must be helpful for understanding the combined influences of the events.

Current status of visualization advancing together with simulation researches on the Earth Simulator

Two kinds of visualization software, MovieMaker and VFIVE, developed at Earth Simulator Center are introduced. MovieMaker is a parallel rendering software for making sequential images from large scale simulation data. VFIVE is a virtual reality visualization software for interactive and immersive visualization in the CAVE system.