Gtrans

Gtrans is a program for performing coordinate transformations. Here you can read more about the program and download it.

About the software

Logotype of Gtrans 4Gtrans is a software program for transforming coordinates for geodetic and cartographic purposes. All current transformations between Swedish national and regional coordinate systems are included in the installation. The user can 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 additonal formats.

Gtrans is designed for transformations and calculations to be made 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 calculation part of Gtrans can also be built into other programs or systems.

Download Gtrans

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

Lantmäteriet renounce 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.

Download the Gtrans installer (exe, 66 MB).

You can subscribe to news about Gtrans if you want to receive emails when new, improved versions of the program is released. In that way you will not miss any information about e.g. bug corrections.

Known issues

There are a few known issues with Gtrans 4.0, which we will correct in the coming version, Gtrans 4.1.

  • The file extension for tf/tfi files must be written in lowercase letters (i.e. .tf and .tfi) in order to import them into a database in Gtrans 4.0.
  • In some cases the transformation parameter estimation give incorrect results. This implies that the residuals will be unreasonably large because of the estimated parameters not being correct. The problem can also become evident by the residuals having a systematic character – such systematics that should normally be absorbed by the parameter estimation.

See a more detailed description of the issues (pdf, in Swedish, new window).

Older program versions

For a long time until version 4.0 was released, version 3.63 of Gtrans was the most recent version. Version 4.0 is modernized with a completely new graphical user interface. If you for some reason need to download Gtrans 3.63, contact the Geodesy department. However, we recommend that you choose version 4.0.

Support and courses

A user manual in Swedish is included in 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.

Training in the program is included as part of the course package Koordinatsystem och Gtrans (taught in Swedish).

E-service for coordinate transformation

You can also transform individual coordinates in Coordinate Transformation e-service that supports the newer Swedish national coordinate and height systems.

Questions and answers

In Gtrans, transformations are organised in databases. Two databases are included in the default installation:

  • SWEREF_99+RH_2000.gdb containing transformations between SWEREF 99 lat/long, geocetric Cartesian coordinates, SWEREF 99 TM and the local SWEREF 99 projection zones. The geoid model SWEN17_RH2000 for transformation between ellipsoidal height and RH 2000 is also included.
  • SWEREF_99+RH_2000+RT+RT+ITRF.gdb containing all the transformations mentioned above, as well as the geoid model SWEN17_RH70 for transformation between ellipsoidal height and RH 70, the preceding geoid models SWEN08_RH2000 and SWEN08_RH70, transformations between RT 90 and SWEREF 99, with and without residual surface; between RT 90 lat/long and the six projection zones; between the regional systems (RT Rnn) 2.5 gon V and RT 90 2.5 gon V, with and without residual surfaces; between RT 38 2.5 gon V and RT 90 2.5 gon V, with residual surface; and the transformation between ITRF2014 and SWEREF 99.

Yes. You can import tf and tfi files to your database in Gtrans 4. To do this, choose Database > Import conversions. This will open the Import Conversions dialog box. At the bottom right, change the file type to "Old Gtrans files (*.tf, *.tfi)".

If the transformation requires multiple steps (e.g. from SWEREF 99 16 30 to lat/long, then on to RT 90 2.5 gon V), Gtrans can automatically create a transformation chain given that all steps are included in your database.

If a transformation step is missing you will need to add it, e.g. by creating it yourself through an estimation or by importing a tf file.

By default, Gtrans displays latitudes and longitudes as degrees, minutes, and seconds to five decimal places.

You can change how latitudes and longitudes are displayed by choosing File > Settings.

Yes. This can be done by writing a plugin in the programming language Lua. You can see how the built-in plugins for k- and csv-files are constructed in the ..\GTransData\Plugins\Coordinates folder.

The GTransData folder contains files connected to Gtrans, e.g. databases containing the transformations that are included in the program, examples of coordinate files and plugins for export and import of files.

You can locate the folder by choosing Application > Open Explorer.

There are no transformation parameters defined to/from WGS 84. The reference frame SWEREF 99 that is used in Sweden, is globally adapted and is equivalent to WGS 84 for many applications.

Read more about the relation between WGS 84 and SWEREF 99.

Contents of this page may be automatically translated, we take no responsibility for the accuracy of the translation. Feel free to contact our customer support centre if you have any questions.

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