Geodetic Zones of Japan JGD2011

Proper understanding of projected coordinates and geodetic zones is crucial for topographic survey, geotechnical survey planning and survey cost estimation.

Evolution of the Geodetic Zones of Japan

The geodetic evolution of Japan involves a transition from the Tokyo Datum to the modern JGD2000 and its subsequent refinement in the JGD2011, accompanied by changes in the associated geoids. 

Geographic Coordinates and Projected Coordinates

Geographic coordinates, based on latitude and longitude, are essential for location references, but they don't provide a convenient framework for measuring distances, areas, or angles. Projection transforms these spherical coordinates into a flat, two-dimensional plane, allowing for more straightforward cartographic representation. 

There are various map projections, each with its strengths and distortions, depending on the intended use. This conversion facilitates precise measurements, aiding in tasks such as navigation, urban planning, and resource management. Additionally, projected coordinates enable the creation of maps that preserve specific properties, like angles or areas, crucial for diverse applications ranging from accurate surveying to spatial analysis in geographic information systems (GIS). 

The difference between geographic coordinates and projected coordinates

In simple terms, we can define the difference between geographic coordinates and projected coordinates as:

• A geographic coordinate defines the location of a gepgraphic element (point, line or surface) on the Earth's surface.
• A projected coordinate allow to draw and to measure such geographic element.

Geographic Projections of Japan

Japan had developed 3 projections: Tokyo Datum, JGD2000, JGD2011.

Tokyo Datum

The Tokyo Datum, established in 1919, served as the foundation for geodetic measurements in Japan for many decades. It was based on the Bessel ellipsoid and was primarily designed for local surveys. As technology advanced, the limitations of this datum became apparent, leading to the need for a more sophisticated and globally compatible system.

The Tokyo Datum was developed considering the Tokyo Datum Geoid. This geoid was tailored to specific requirements of the Bessel ellipsoid.

Japan Geodetic Datum JGD2000

In response to the growing demand for global compatibility, Japan adopted the Japan Geodetic Datum 2000 (JGD2000). This datum transitioned from the Bessel ellipsoid to the GRS80 ellipsoid, aligning Japan's geodetic system with international standards. The shift not only improved accuracy but also facilitated seamless integration with global positioning systems (GPS).

Japan Geodetic Datum JGD2011

Recognizing the dynamic nature of the Earth's crust, Japan further refined its geodetic system with the introduction of the Japan Geodetic Datum 2011 (JGD2011). This update aimed to account for tectonic plate movements and seismic activities, especially the 2011 Great Tohoku Earthquake, ensuring that the geodetic reference frame remained accurate over time. JGD2011 enhanced the precision of geospatial data, especially in regions prone to geological shifts.

The 18 geodetic zones of Japan

The current JGD2011 consists of 18 geodetic zones, each one covering a specific area of the territory of Japan.

This link will redirect you to a Google Maps application showing the coverage of the 18 Japanese geodetic zones and your current location