Reference systems

We distinguish between three basic surfaces

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.

Traditionally the horizontal and vertical reference systems have been separated but with the advent of satellite technology for positioning, globally adapted three-dimensional reference systems are needed.

It is important to specify the reference system

Since the position of a point can be given in different reference systems, it is important to state which reference system the information refers to.

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, new window).

Introduction of SWEREF 99 and RH 2000

Lantmäteriet works for national coordination in geodesy matters and has for many years contributed with advice and support regarding the introduction of SWEREF 99 and RH 2000 in other organizations.

International cooperation

Reference systems are by their nature a global subject area and therefore international cooperation is a very important part in the development and management of reference systems.