Recent developments and future directions of Japan geodetic system

Abstract

The Geospatial Information Authority of Japan (GSI) has established and maintained horizontal and vertical control network for land survey in Japan, which consists of about 130,000 control points such as GNSS earth observation network (GEONET) stations, triangulation stations, and bench marks. The horizontal coordinates (latitude and longitude) or orthometric height of the stations and bench marks are published as survey results, and utilized for public surveys. The development of GNSS technique and GEONET gave a strong momentum to improving efficiency of surveying for control points. Although the surveying for public control points had been based on triangulation points, a new survey procedure, in which GNSS surveying can be conducted with only GEONET stations as reference points, was introduced on public survey in Japan in April 2002. After that, semi-dynamic correction was also introduced to reduce the adverse effects of the distortion due to crustal movement in public surveys in January 2008. GEONET has been also utilized for orthometric height determination by GNSS surveying since April 2014. Considering the development of GNSS survey technique and GEONET stations as stable reference points, the GSI decided to switch main geodetic control points from triangulation points to GEONET stations in next 10 years and publicly announced the new direction at the end of June 2014.