geodetisk

Geodetisk, or geodetic in English, is the branch of geodesy that focuses on measuring the size and shape of the Earth, its gravity field, and its orientation in space, as well as on defining reference frames and coordinate systems for accurate mapping and positioning. Geodetic work provides models and datums that enable consistent measurements across time and space, forming the basis for navigation, surveying, and geospatial information.

Key concepts in geodetisk include the reference ellipsoid, the geoid, and geodetic datums. The ellipsoid is a mathematical approximation of Earth’s shape, while the geoid represents mean sea level influenced by gravity. A datum links the mathematical model to real-world locations and defines a coordinate system (for example WGS84, NAD83). Vertical datums relate to heights relative to sea level and are essential for height measurements and flood risk assessment.

Measurement methods combine long-standing field techniques with modern satellite and space-based technologies. Historical methods included triangulation, trilateration, and precise leveling. Today, global navigation satellite systems (GNSS) such as GPS, GLONASS, Galileo, and BeiDou are central, supported by techniques like very long baseline interferometry (VLBI) and satellite laser ranging (SLR) to determine Earth orientation and scale. Gravimetry maps gravity variations, and geodynamic monitoring uses these data to study crustal movement and changes in the Earth’s rotation.

Applications of geodetisk span mapping, land surveying, civil engineering, navigation, GIS, and scientific research into crustal deformation, sea-level rise, and other geophysical phenomena. The field evolves with advances in positioning technology and space geodesy, continually refining global and regional reference frames.