Local transformations

Do you need to transform coordinates between national reference systems and the local coordinate systems that have been used in the municipalities? There are two different types of transformations, and which one to choose depends on the origin of your coordinates.

Transformations including a correction model

If your data have their coordinate origin in the geodetic reference network of the municipality, a transformation with correction model should be used in the first place.

When the municipalities were to switch to SWEREF 99 in their applications, transformation parameters were developed for the municipal coordinate systems. It was often done in collaboration between Lantmäteriet and the municipality. Typically, the coordinate transformation includes a model of residuals to handle distorted geometries in the older coordinate systems.

A model of residuals, or correction model, is a type of rubber-sheeting algorithm that is used to rectify distorted reference systems when performing a coordinate transformation to a reference system with homogeneous geometry.

It was common that several different coordinate systems were used within the same municipality, and in general there are transformation relationships for all local coordinate systems that the municipality used before doing its transition to SWEREF 99.

Contact the geodesy department to get the transformations with models of residuals between the municipal systems and SWEREF 99.

RIX 95 transformations

If you have data from network RTK measurements, which were transformed to the local coordinate system with the so-called RIX 95 transformation without local connection, you should use the inverse of this transformation, to transform your data back to SWEREF 99.

RIX 95 was a project that aimed at, among other things, providing transformation parameters connections between local (municipal) and national reference systems.

The transformation parameters from the project do not give the same transformation results as the transformations with model of residuals, but may need to be used in applications that do not have the possibility of interpolation in a model of residuals.

Contact the geodesy department to get the RIX 95 transformations.

In-depth information

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