WGS 84 — Past, Present and Future

The World Geodetic System (WGS) was conceived as a practical geodetic reference system that maintains consistency with the best scientific terrestrial reference system at the time but also retains some stability. It has evolved from its beginnings as WGS 60 to its present manifestation as WGS 84. A significantly improved Earth Gravitational Model and global geoid were released in 1996, and the realization of the WGS 84 reference frame is consistent with the International Terrestrial Reference Frame (ITRF) 1994 at the 5-cm level. Evaluations of WGS 84 relative to ITRF94 have been made by comparing International GPS Service (IGS) GPS orbits with the National Imagery and Mapping Agency’s precise orbits and by computing WGS 84 positions for a globally distributed set of IGS stations with known ITRF94 coordinates. The results indicate that there is no practical difference between ITRF94 and WGS 84 for mapping, charting, navigation and many survey applications.