SPACE-W (Space Weather International Collaborative Research) Database in Japan Observation (SPACEW-J-SM0010) Version 1.0 March 2004 (CAWSES database in Japan) 3-Dimensional Visualization Using VRML: Method and Examples

SM0010

This DVD-ROM contains the method to use VRML (Virtual Reality Modeling Language) by Fortran and many examples of 3-dimensional visualization obtained from the computer simulation of solar wind-magnetosphere interaction.

1. How to use VRML by Fortran

  Three-dimensional visualization is indispensable in order to understand 3-dimensional simulation results such as the earth's magnetosphere better. By appearance of the VRML which is only the international standard language for the Internet's 3-dimensional visualization, it would be possible to watch the 3-dimensional image as VRML file by the VRML viewer, even if people does not have 3-dimensional image processing special computers and 3-dimensional image processing special software. However, utilization and popularization of the VRML do not advance very much in present state, because there is no a convenient tool which easily makes the VRML file and also it is not easy to make the complicated VRML file.

  In order to develop the method for visualizing 3-dimensional simulation result of the magnetosphere by using the VRML, we have wrestled in making the VRML file earlier by utilizing experience and knowledge cultivated for a long time for the image processing using Fortran and C language. In the computer science and technology project as the extension, we have made this manual "How to Use VRML" for the purpose of the 3-dimensional visualization of the simulation results by presenting interface subroutine packages for the VRML contents preparation by Fortran and C language.

This DVD-ROM includes all main Fortran programs and subroutine packages shown in this manual as a source program format. We are happy if it is useful for the simulation and data analysis scientists.

2. Computer Simulation and 3-Dimensional Visualization Using VRML

Three-dimensional visualization is necessary in order to understand what is obtained in the 3-dimensional and global MHD simulation of the solar wind and earth's magnetosphere interaction. For example, movement and rotation of coordinate axes are a method for better understanding of configurations of 3-dimensional magnetic field lines. Appearance of the VRML has drastically changed the situation of 3-dimensional image processing and has freed 3-dimensional visualization from the special computer and the special software. Though the speed of the 3-dimensional image processing (rotation, scaling, etc.) depends on the ability of the computer, VRML viewers such as Cosmo Player make possible the image processing for everyone by using browsers such as recent Netscape and Internet Explorer.

In order to make the VRML file, we prepare the Fortran Interface Subroutine Package, and VRML file (*.wrl) is directly made from 3-dimensional simulation data using Fortran program. Though there is a difference between 2-dimension and 3-dimension, this method is similar to the method for making the PostScript image file. In the VRML viewer, there are generally "walk mode" and "examine mode". The walk mode moves the viewpoint, and the examine mode does transfer and rotation and scaling of the object. It is possible to examine more apparently the 3-dimensional structure of the magnetosphere in this way. Present important problem is large VRML, since it is ascii file. It is future most interesting problem to display a real 3-dimensional animation movie.

Many practical VRML examples for 3-dimensional visualization of the earth's magnetosphere which have been obtained from the global MHD simulation of interaction between the solar wind and magnetosphere by using various 3-dimensional MHD models are also presented. We are happy if many scientists are interested in the 3-dimensional visualization contents of VRML World.

3. Structure of Directory of VRML Files

The structure of directory of 3-dimensional MHD codes and VRML files in the DVD-ROM is summarized in the directory, "structure.txt". There are many kind of 3-dimensional MHD (magnetohydrodynamics) codes of magnetosphere such as a quarter model (with north-south and dawn-dusk symmetry), a half model (with IMF By and Bz components, with dipole tilt) and a full model without any symmetry. The method to use VRML includes all the subroutine packages, Fortran source program, produced VRML files and explanation for use. Some of the VRML contents of 3-dimensional MHD simulation of Earth's magnetosphere and Jovian Magnetosphere are compressed by "gzip" to present a compressed VRML file like "pxd4mde32v.hde1b300.wrl.gz", because the file size of ASCII VRML file becomes very large. So, one need to decompress the compressed the VRML files by "gzip -d file-name.gz" in order to look at them in each personal computer.

3.1. 3-Dimensional Magnetohydrodynamic (MHD) Model of Interaction between

     the Solar Wind and Earth's Magnetosphere

     ./mhdmodel     :3D MHD codes

     ./mhdmodel2    :3D MHD codes

     ./hpfja        :3D MHD codes by High Performance Fortran/JA

     ./vppfort      :3D MHD codes by Fujitsu VPP Fortran

     ./postscript   :Graphic tool by PostScript Language

3.2. Method to Use VRML (Virtual Realty Modeling Language):

     How to Use VRML by Fortran and C

     ./vrml/vrml1   :fundamental Fortran Program

     ./vrml/vrml2   :fundamental Fortran Program

     ./vrml/vrmlap  :fundamental Fortran Program and Application

3.3. Example of VRML Contents

     ./example/yinyang     :Yin-Yang grid

     ./example/grid        :Projection grid

     ./example/stelab      :STElab building

     ./example/toyotahall  :Toyata Hall of Nagoya University

     ./example/shape       :VRML contents of various shapes

3.4. VRML Contents of 3-Dimensional MHD Simulation of Earth's Magnetosphere

     and Jovian Magnetosphere

     ./magne      :3D magnetic field lines

     ./jupiter    :Jovian magnetosphere

     ./quadrupole :quadrupole magnetosphere

     ./eartha1    :half model with IMF By and Bz components

     ./earthb1    :quarter model with north-south and dawn-dusk symmetry

     ./earthc1    :half model with dipole tilt

     ./earthd1    :full model with IMF Bx component

     ./earthd2    :full model with IMF Bx component

     ./tokutake   :half model with IMF By and Bz components

Project team of "Development and standardization of the visualization tool by the VRML"

    Tatsuki Ogino ( Leader )

    Maki Nakao

    Yuka Kadowaki

    Minako Suganuma

    Manami Inayoshi

    Koichi Ota

    Keiichiro Fukazawa

    Dai Owaki

    Kazuhide Sawada

Acknowledgments:

Support for the production of SPACE-W Database was provided by Grants-in-Aid from the Japan Society for Promotion of Science (JSPS). Computing support was provided by the information Technology Center of Nagoya University.

Contacts:

Prof. Tatsuki Ogino

Solar-Terrestrial Environment Laboratory, Nagoya University

3-13 Honohara, Toyokawam, Aichi 443-8507, Japan

TEL: +81-533-89-5207   FAX: +81-533-89-5090