Geoid is the shape of Earth's ocean surface without wind and tide effects. It extends through continents and is irregular but smooth. Geoid's deviation from ellipsoid ranges from +85m to -106m
IGS products support scientific research in various Earth parameters. Products include satellite ephemerides, station positions, and clocks. Products cover ITRF realization, Earth deformation, and hydrosphere monitoring
Efforts began in 19th century with Helmert's book on geodesy. Austria and Germany established Central Bureau for International Geodesy. WGS 60 was developed by US military in 1960
Geographic coordinate conversion involves translating between different coordinate formats and systems. Conversion is necessary due to varying coordinate systems worldwide and over time. Applications include cartography, surveying, navigation and GIS
Earth's figure is used to model planet Earth's size and shape. Spherical Earth is a historical approximation suitable for many purposes. Earth's radius is approximately 6,371 km, deviating from spherical by 0.3%
Latitude measures north-south position from Equator, longitude east-west from Greenwich. Both measured in degrees, minutes, seconds, or decimal degrees. North and South Poles are at 90° north and south