Geospatial Information Authority of Japan

GSI, being the competent authority of the Survey Act, conducts national surveying and mapping activities, which provide a basis for the land management.

Historically it dates back to 1869 when cadastral Registration Map Section was established in the office of Geography Department, Ministry of Civil Service. Later in 1888 it was reorganized as Japanese Imperial Land Survey, and finally in 1945 it became the Geographical Survey Institute. In April 2010, the official English appellation is changed to "Geospatial Information Authority of Japan."

The surveys GSI performs provide positional data (longitudes and latitudes) of the land and elevations from the mean sea level. A triangulation point and a benchmark give the exact position and elevation of that particular point on the earth, respectively. Today in addition to them GPS-based control stations are established for precise positional measurements where signals from the GPS satellites are continuously observed.