Høydeekstrapolering

Høydeekstrapolering, or height extrapolation, is a technique used in geophysics and surveying to estimate ground surface elevation based on data from a different vertical datum. This often involves adjusting elevation values measured relative to a local or temporary datum to a more universally accepted or stable datum, such as mean sea level or a national geodetic vertical datum. The process typically relies on a network of control points where elevations are known for both the source and target datums.

The necessity for height extrapolation arises when measurements are taken in areas where a standard datum is not readily accessible or has not been established. For instance, during construction projects or remote sensing surveys, elevations might be recorded relative to a temporary benchmark or a locally defined zero point. To integrate these measurements into larger-scale mapping or scientific studies, they must be converted to a consistent datum.

Methods for height extrapolation can range from simple additive constants, when the difference between datums is relatively uniform across the area of interest, to more complex interpolation techniques. These sophisticated methods use spatial data, such as gravity models or existing topographic maps, to model the variations in the vertical separation between datums. The accuracy of height extrapolation is highly dependent on the density and quality of the control data and the chosen extrapolation model. Errors in extrapolation can lead to significant inaccuracies in derived elevation models, impacting subsequent analysis and applications.