Korkeusjärjestelmille

Korkeusjärjestelmille refers to height systems or vertical datums used in geodesy and surveying. These systems are essential for defining and measuring elevations above a reference surface, ensuring consistency and accuracy in mapping, construction, and navigation. Different countries and regions often employ their own specific height systems, which can lead to variations in reported elevations.

The fundamental concept behind a height system is the establishment of a zero level, or datum. This datum is typically based on mean sea level, although other reference surfaces like geoids or ellipsoids can also be used. The geoid, which approximates mean sea level, is considered the true equipotential surface of gravity and is often the preferred reference for precise height measurements. An ellipsoid, a mathematical model of the Earth's shape, is used for horizontal positioning but requires a transformation to determine orthometric heights, which represent the height above the geoid.

Common types of heights include orthometric height (H), which is the practical height above sea level, and ellipsoidal height (h), which is the height above the reference ellipsoid. The difference between these two is the geoid undulation (N), so H = h - N. Understanding the specific height system being used is crucial to avoid errors in data interpretation and application. The development and maintenance of these systems involve sophisticated geodetic measurements and modeling techniques.