You are using an old browser

We cannot guarantee the full functionality of the website in the Internet Explorer browser. Feel free to try another browser.
Listen

Transformations

A transformation is a conversion of coordinates from one coordinate system to another. Coordinate transformations need to be done, for example, to be able to present different geographic data sets together, if they are not already given in the same coordinate system.

ITRF – SWEREF 99

When is coordinate transformation between ITRF and SWEREF 99 required?

When using certain positioning services and GNSS calculations, you may need to perform coordinate transformations between ITRF/WGS 84 and SWEREF 99.

Positioning services based on Precise Point Positioning (PPP) give coordinates in the latest ITRF, International Terrestrial Reference Frame, current epoch, which can be said to be about the same as WGS 84. You can also obtain such coordinates when, for example, performing relative GNSS processing against stations in the IGS network (new window).

The global reference system ITRS, International Terrestrial Reference System, is dynamic and includes a velocity model. The definition of SWEREF 99 means that Sweden's position on the globe is fixed to Europe's position in 1989, and that it is a static system in terms of geodynamic movements, such as plate tectonics and post-glacial land uplift. The difference between SWEREF 99 and WGS 84 is at present (2024) 8–9 dm, increasing by a few centimetres per year.

Transformation ITRF2014 – SWEREF 99

When transforming coordinates between ITRF and SWEREF 99, the transformation between ITRF2014 and SWEREF 99 should be used in the first place, as it is the most up-to-date relationship.

If you need to transform between any other ITRF solution and SWEREF 99, the official ITRF transformations between the different solutions (new window) should be used for transformation to ITRF2014, and the transformation below to transform between ITRF2014 and SWEREF 99.

This transformation is available in the PROJ transformation library (new window), version 7.2.1 and later. The transformation is also available through Lantmäteriet's own software for coordinate transformations, Gtrans, version 4.0 and later.

The transformation method is described in NKG2020 transformation: An updated transformation between dynamic and static reference frames in the Nordic and Baltic countries (new window).

Transformation ITRF2005 – SWEREF 99

There is an older transformation between ITRF2005 and SWEREF 99, which you should only use if you have used the transformation before and need to continue using the same transformation to get consistent results.

Contact the Geodesy Department to get access to the transformation.

Simplified transformations

The simplified transformations are designed for situations where interpolation in the deformation grid cannot be handled. The transformations consist of annual parameters for a 7-parameter transformation. The expectation is that the need for this type of transformation will decrease now, when the general and accurate transformation between ITRF and SWEREF 99 is available in PROJ and Gtrans.

Geoid models

Here you can download the national geoid models for RH 2000 and RH 70.

SWEN17_RH2000

SWEN17_RH2000 is a geoid model that has been adjusted to SWEREF 99 and the height system RH 2000. The model is based on a gravimetric geoid model in combination with interpolation of GNSS/levelling residuals to make the transition from heights above the ellipsoid in SWEREF 99 to heights above sea level in RH 2000. The postglacial land uplift between the reference epoch of SWEREF 99, which is 1999.5, and the reference epoch of RH 2000, which is 2000.0, has been taken into account.

The standard uncertainty of SWEN17_RH2000 has been estimated to 8–10 mm everywhere on the Swedish mainland, Öland and Gotland, with exception of a few areas where the uncertainty is larger. These areas are in the far north on the border to Norway and in the lake Vättern (standard uncertainty approximately 2–3 cm) and the highest mountains to the north-west, depending on the difficulties to model a gravimetric model in mountainous areas (standard uncertainty about 2–4 cm). At sea, the standard uncertainty is also larger; about 2–3 cm in coastal waters and probably around 5–10 cm further out.

The geoid model is represented by geoid heights in a regular grid, from which geoid heights at other points can be calculated using an appropriate interpolation method, e.g. bicubic splines. Bilinear interpolation using the four closest nodal points will result in a slightly larger interpolation error, but still very small compared to the uncertainty of the geoid model. Compared to prior geoid models, the grid resolution is twice as high. The resolution is the same as for the underlying gravimetric geoid model, i.e. 0.01 x 0.02 degrees, in order not to miss out on high-frequent information in the gravimetric geoid model. However, this means that the geoid files are larger.

The geoid model is available for download in three different formats, either as a binary grid or two different ASCII formats. The geoid files, as well as interpolated control points, can be found below.

SWEN17_RH70

SWEN17_RH70 is the corresponding model for conversion from SWEREF 99 to the older height system RH 70. This model has been computed from SWEN17_RH2000 by taking into account the difference between the two height systems in question. The model accounts for the postglacial land uplift and interpolation of the GNSS/levelling residuals is utilized.

The postglacial land uplift correction refers to 29.5 years of uplift, between the reference epoch of SWEREF 99 (1999.5) and the reference epoch of RH 70 which is 1970.0.

The standard uncertainty of SWEN17_RH70, close to the benchmarks of the national precise levelling network, is similar to the one of SWEN17_RH2000 on land, under the assumption that RH 70 is considered as realised by the RH 70 heights of stable benchmarks along the precision lines of the second precise levelling and the RHB 70 heights for the benchmarks of the third precise levelling.

Files from Lantmäteriet

Lantmäteriet's geoid models SWEN17_RH2000 and SWEN17_RH70 are distributed under the open data licence Creative commons, CC0 (new window).

SWEN17_RH2000

SWEN17_RH70

Control points

Files from suppliers of GNSS equipment and software

SWEN17_RH2000

SWEN17_RH70

Gtrans

About the software

Gtrans 4 logotype

Gtrans is a software for transforming coordinates for geodetic and cartographic purposes. Current transformations between Swedish national and regional coordinate systems are included in the installation. Users can also create and add custom transformations and coordinate systems.

The program can read the file formats csv, k-file and lua. Users can program their own plugins to read and write additional formats.

Gtrans is designed for transformations and calculations to be performed with correct algorithms and with sufficient precision. The program is developed by the Geodesy department at Lantmäteriet, but has also been widely distributed outside Lantmäteriet.
The computation core of Gtrans can be built into other programs or systems.

Gtrans is available also in other languages than Swedish. The language of the operative system controls the language of the software.

Download Gtrans

Gtrans may be used free of charge for any purpose. Lantmäteriet strives to make the program as good as possible but takes no responsibility for any errors.

Lantmäteriet renounces all responsibility for this software being free from interruptions, safe or free from errors. Lantmäteriet cannot be held responsible for any damages arising from the use of this software. Any use of this application is at the user's own risk.

Version history

New in version 4.1.2

  • A bug in the fitting module is fixed. The bug present in versions 4.0–4.1.1 caused errors in creation of conversions containing a model of residuals, through fitting. Contact the Geodesy department if you need help to correct possibly erroneous models of residuals created in earlier software versions.
  • Guide for creation of more varieties of coordinate systems within the reference systems RT 90, RT 38 and the regional systems RT Rnn, beyond the selection of systems that already is available in Gtrans. The guide is a tool for addition of coordinate systems in all projection zones, with any false Northing/Easting. Conversions to/from all such RT coordinate systems will then be added and/or constructed automatically by Gtrans.
  • Support for conversions to and from ITRF2020.
  • Support for conversions to and from MGRS (Military Grid Reference System) and GeoRef (World Geographic Reference System).
  • Section 3 in the user manual has been updated with a description of how to import older Gtrans3 conversions and a description of how to import conversions from lua files.

New in version 4.1.1

  • When doing an estimation, it is possible to create a report when the new conversion is stored in the database.
  • When a height conversion is added to a conversion to/from ITRF, the name of the conversion is now correct.
  • When Gtrans is started in another language than Swedish or English, the program does not crash.

New in version 4.1

  • Improved functionality in the estimation module. Among other things, the residual error vectors are plotted correctly and the map support has been updated. Estimations are iterated until convergence is achieved so that the fitting result is correct and there is a possibility of searching for outliers among estimation points. It is possible to print a report with the estimation results and to export the created transformation to a file.
  • Improved plugins for importing and exporting CSV  and k files.
  • Bug fixes and smaller improvements in functionality.
  • Gtrans is also available in English; the user interface as well as user manual and report of the estimation result. The language of the operative system controls the language of the software.
  • The installation package is signed with Lantmäteriet as the verified publisher.

Support and courses

A user manual is included with the installation and describes the basic functionality of the program. You can find it by choosing Application > User guidelines in the program. If you have further questions, contact the Geodesy department.