Nobuaki Ohno

Virtual reality visualization by CAVE with VFIVE and VTK

The CAVE-type virtual reality (VR) system was introduced for scientific visualization of large-scale data in the plasma simulation community about a decade ago. Since then. we have been developing a VR visualization software. VFIVE, for general CAVE svsteins. Recently, we have integrated an open-source visualization library, the Visualization Toolkit (VTK), into VFIVE, Various visualization methods of VTK can lie incorporated and used interactively in VFIVE.

Visualization of spherical data by Yin–Yang grid

Abstract Visualization in the spherical geometry is ubiquitous in geophysical data processing. For the spherical visualization, the commonly used spherical polar coordinate system is not ideal due to its grid convergence nature near the poles. We propose to use a spherical overset grid system called Yin–Yang grid as the base grid system of the spherical visualization. The convergence-free nature of the Yin–Yang grid leads to a balanced data distribution and effective visualization processing in a sphere. The Yin–Yang grid is already used in various geophysical simulations including the geodynamo and mantle convection in the spherical geometry. Data produced by the Yin–Yang grid can be, and should be, visualized directly on the same Yin–Yang grid system without any data remapping. Since the component grid of the Yin–Yang grid is a part of (or low latitude region of) the standard spherical polar coordinate system, it is straightforward to convert an existing spherical visualization tool based on the spherical polar coordinates into a tool based on the Yin–Yang grid.

Macro?micro interlocked simulation algorithm: an exemplification for aurora arc evolution

Using an innovative holistic simulation algorithm that can self-consistently treat a system that evolves as cooperation between macroscopic and microscopic processes, the evolution of a colorful aurora arc is beautifully reproduced as the result of cooperation between the global field-aligned feedback instability of the coupled magnetosphere–ionosphere system and the ensuing microscopic ion-acoustic instability that generates electric double layers and accelerates aurora electrons. These results are in agreement with rocket and satellite observations. This shows that the proposed holistic algorithm could be a reliable tool to reveal complex real dramatic events and become, in the near future, a viable scientifically secure prediction tool for natural disasters such as earthquakes, landslides and floods caused by typhoons.

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.

IMMERSIVE VR VISUALIZATIONS BY VFIVE PART 1: DEVELOPMENT

We have been developing a visualization application for CAVE-type virtual reality (VR) systems for more than a decade. This application, VFIVE, is currently used in several CAVE systems in Japan for routine visualizations. It is also used as a base system of further developments of advanced visualizations. The development of VFIVE is summarized.

IMMERSIVE VR VISUALIZATIONS BY VFIVE PART 2: APPLICATIONS

VFIVE is a scientific visualization application for CAVE-type immersive virtual reality systems. The source codes are freely available. VFIVE is used as a research tool in various VR systems. It also lays the groundwork for developments of new visualization software for CAVEs. In this paper, we pick up five CAVE systems in four different institutions in Japan. Applications of VFIVE in each CAVE system are summarized. Special emphases will be placed on scientific and technical achievements made possible by VFIVE.

Region-of-interest visualization by CAVE VR system with automatic control of level-of-detail

Abstract To specify the region of interest (ROI) is an effective approach to visualize large scale simulation data. We have developed a three-dimensional visualization software with ROI function for the CAVE virtual reality systems. This software enables the user to perform fully three-dimensional and interactive visualization of large scale computational fluid dynamics (CFD) data. The user specifies a ROI in the CAVE room by a three-dimensional “mouse-drag”. The data in the specified ROI is automatically extracted from the original CFD data. This ROI procedure can be repeated recursively. The resolution in each ROI is kept approximately constant. A data set of three vector fields and eight scalar fields whose size is about 1 GB each was successfully analyzed.

Images of Aurora Light Based on Macro–Micro-Interlocked Simulation

To understand the aurora arc formation, a simulation code using a macro-micro-interlocked algorithm has been developed and implemented on the original Earth Simulator. Based on the results, aurora light has been rendered taking the emission from oxygen atoms excited by precipitating energetic electrons into consideration using an original parallel-visualization software.

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.