The geodetic description of the Earth distinguishes between three fundamental surfaces.
- The Earth's surface, which includes the sea surface where there are seas, is the surface on which we live.
- The geoid is the equipotential surface of the Earth's gravity field that best connects to the sea surface.
- The Earth ellipsoid is the rotational ellipsoid that best connects to the geoid.
To define the position of points on the Earth's surface we need geodetic reference systems based on these three surfaces, their internal relations and their changes over time.
Lantmäteriet is the responsible authority
We are responsible for the national reference systems: SWEREF 99 in three dimensions and on the plane, RH 2000 in height and RG 82 for gravity. To secure height measurements using GNSS, we are also responsible for the geoid model SWEN17_RH2000.
Overview of Swedish reference systems (pdf).
Here you find interactive services for transformation of co-ordinates or computation of geoid heights.