Referenssielipsoid
A referenssielipsoid, or reference ellipsoid, is a mathematically defined surface that approximates the shape of the Earth. It is a prolate spheroid, meaning it is an ellipsoid of revolution generated by rotating an ellipse around its shorter axis. This shape is chosen because the Earth is not a perfect sphere; it bulges slightly at the equator due to its rotation. The referenssielipsoid provides a fundamental geometric basis for geodetic datums, which are used to define locations on the Earth's surface.
Various referenssielipsoids have been developed over time, each with slightly different parameters for its semi-major and
The parameters of a referenssielipsoid are typically defined by its semi-major axis (a), which is the distance