Vol.52-2 CONTENTS

Hiromichi TSUJI and Kazuo KOMAKI

The recent change of the geodetic reference system of Japan from the Tokyo Datum to the Japanese Geodetic Datum 2000 (JGD2000) is an ongoing process to keep the system precise and up-to-date for the various demands of modern society. In the rapidly changing archipelago over tectonic plate converging zones and with the advent of an information society, future directions of the national geodetic reference system require special thought. A combination of GPS and information technology is now leading to the emergence of a Location Based Services (LBS) where positional information plays a key role to relate real space to cyberspace, opening up a geo-information society. Although the basic role of the geodetic reference system to control precise coordinates for surveying never change, a new role to support precise, real-time positioning should be developed. In addition, incessant crustal deformation in Japan should be properly handled by a semi-dynamic correction system for precise surveys with GPS. This paper presents a future design of the national geodetic reference system, introducing the concept of Geo-Referencing Infrastructure for Dynamic Japan (GRID-Japan). Through the partnership of local governments and the private sector, GSI will start the process of realizing the concept of GRID-Japan in the next ten years.

1. Introduction
2. The current Japanese Geodetic System: JGD2000
3. Driving forces beyond JGD2000
  3.1 Accumulating crustal deformations
    3.1.1 Deviations from ITRF
    3.1.2 Deformation of network
  3.2 Trends in technology and society
    3.2.1 Future of GPS and satellite positioning system
    3.2.2 Emergence of Location-Based Services (LBS)
  3.3 Voices from users
4. Design of a future geodetic reference system
  4.1 Basic functions as survey reference and crustal deformation monitoring
  4.2 New function to support LBS
  4.3 Robust system through synergy
    4.3.1 GPS with VLBI
    4.3.2 Conventional and GPS-based control points
  4.4 Reference in a dynamic and deforming Japan
    4.4.1 Deformation monitoring by GEONET
    4.4.2 Necessity of crustal deformation correction
    4.4.3 Re-surveys of conventional control points
    4.4.4 Methods of deformation correction
5. GRID-Japan concept
  5.1 What is GRID-Japan ?
  5.2 Outcome targets
  5.3 For implementation
6. Conclusions
Acknowledgements
References