Ortometriseen

Ortometriseen is a Finnish term that can be translated to "orthometric" in English. It refers to the measurement of height relative to a geoid, which is an idealized mean sea level surface. This is in contrast to ellipsoidal heights, which are measured relative to an ellipsoid of revolution, a simpler mathematical model of the Earth's shape.

Orthometric heights are crucial in many scientific and engineering applications. For instance, they are used in hydrology to understand water flow and in civil engineering for designing infrastructure like dams and canals where the precise vertical position of water is critical. They are also important in geodesy for establishing vertical datums and in mapping for creating accurate topographic maps.

The calculation of orthometric heights typically involves using the ellipsoidal height obtained from GPS measurements and then applying a geoid model to correct for the undulations of the geoid relative to the reference ellipsoid. These geoid models are developed through extensive gravimetric surveys and other geodetic data. The difference between the ellipsoidal height and the orthometric height is known as the geoid separation or geoid undulation. Understanding and accurately determining orthometric heights is essential for consistent and reliable height referencing across different locations and over time, especially when dealing with large-scale projects or scientific studies that require high precision.