Two-dimensional systems - Presentation
For practical purposes it is easier to use plane co-ordinates than three-dimensional co-ordinates. A plane reference system is therefore often used to define positions. The choice of reference system depends on the purpose of the positioning. National reference systems are used to describe small-scale information, but a more locally adapted reference system should be used to depict large scale information.
Plane co-ordinate systems are often connected to a three-dimensional reference system by a map projection. To have the reference system more locally adapted - to reduce the projection errors - a central meridian can be chosen that is close to the working area. A purely local reference system can also be established. Local reference systems can in turn be connected to a superior reference system.
Information about the Swedish plane reference systems is given on the right. More information about map projections is given on the map projection page (in Swedish).
