korkeusviitejärjestelmät

Korkeusviitejärjestelmät, often translated as vertical datum or height reference system, are established reference surfaces used to define and measure elevations or heights of points on the Earth's surface. These systems are fundamental for various applications, including surveying, mapping, navigation, coastal management, and engineering projects. The primary goal of a height reference system is to provide a consistent and predictable way to quantify how high or low a particular location is relative to a defined baseline.

There are two main types of vertical datums: those based on mean sea level (MSL) and those based on a geoid. Mean sea level datums are historically common and represent an average of tidal heights over a period of time. However, sea levels can vary due to factors like ocean currents and atmospheric pressure, making them less stable. Geoid-based datums, on the other hand, are derived from a model of the Earth's gravity field. The geoid is an equipotential surface that best approximates mean sea level and is considered a more stable and scientifically accurate reference.

Different countries and regions may utilize their own national or local vertical datums. Furthermore, advancements in satellite technology and gravimetry have led to the development of global vertical datums, aiming for a unified system worldwide. The choice of a specific height reference system depends on the required accuracy, the scale of the project, and the available geodetic infrastructure. Accurately establishing and maintaining these systems is crucial for ensuring consistency and reliability in all georeferenced data.