JGD2000 (Japanese Geodetic Datum 2000 | EPSG:4612)

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Introduction

JGD2000 is the national surveying system of Japan officially adopted by the Geospatial Information Authority of Japan in April 2002, replacing the previous “Tokyo Datum”. The main purpose of its introduction is to enhance the coordination with the global GPS coordinate system. JGD2000 is based on the geocentric coordinate system (ITRF: International Terrestrial Reference Frame) with the center of the earth as the origin, thus achieving higher-precision measurement and GIS analysis capabilities.

Coordinate System Composition

JGD2000 mainly includes the following three data formats:

Geodetic coordinates (latitude, longitude, ellipsoid height)

Using the GRS80 ellipsoid as the benchmark, using latitude and longitude to represent the point position, and recording the ellipsoid height as the elevation information.

Rectangular coordinates (XYZ)

Three-dimensional rectangular coordinates (ECEF coordinate system) with the center of the earth as the origin, often used in conjunction with global positioning systems such as GPS.

Plane rectangular coordinates (X, Y)

Widely used in mapping and civil engineering design in Japan. Japan is divided into 19 projection zones, and each area uses the corresponding reference point for projection conversion.

Pros

Highly consistent with international standards: Based on ITRF, JGD2000 can be connected with GPS and other international surveying and mapping data with high precision.
Support high-precision measurement: In scenarios requiring GNSS precision observation or 3D measurement, JGD2000 provides stable and reliable coordinate support.
National unified standards: All types of survey results and public surveying and mapping use the same benchmark, which helps to manage spatial data consistency.
Compatible with existing systems: The maps of the National Institute of Land and Geography and many public spatial data are based on JGD2000, which facilitates system integration and data integration.

Cons

Affected by crustal movement: As a fixed reference system, JGD2000 is difficult to cope with crustal changes caused by plate movement or earthquakes in the long term.
Differences with JGD2011: There may be a deviation of several centimeters to tens of centimeters between JGD2011 and JGD2000, which were launched after the Great East Japan Earthquake in 2011. Special attention should be paid to mixing.
The conversion of old data is cumbersome: The conversion from the old Tokyo Datum to JGD2000 requires a certain amount of conversion and update work, which is a challenge for the management of old data assets.

Application Scenario

JGD2000 is the standard coordinate system used in almost all surveying, mapping, infrastructure design, disaster response, urban planning, and GIS analysis in Japan. The topographic maps and basic map information released by the Ministry of Land, Infrastructure, Transport and Tourism and local governments are based on JGD2000. At the same time, construction engineering companies, consulting agencies, universities, and research institutions also widely use this benchmark system in civil design, drone mapping, 3D modeling, smart city construction, etc. In addition, web map services such as “Geographical Information Institute Map” and many GIS platforms (such as OpenStreetMap) also provide data based on JGD2000. Faced with the growing demand for high-precision spatial information, JGD2000 has become an indispensable “spatial information foundation” in Japan.

Example

The difference between the Japanese geodetic system and the world geodetic system (Source: Geospatial Information Authority of Japan).

Processing JGD2000 survey maps in AutoCAD.