GtransReprojector
Reprojects feature coordinates from one coordinate system to another using the Gtrans reprojection engine from the National Land Survey of Sweden (Lantmäteriet).
Typical Uses
- Reprojecting features when explicitly using the Gtrans engine is desired
- Reprojecting features in select local coordinate systems not supported elsewhere
How does it work?
The GtransReprojector receives raster, vector, or point cloud features and reprojects their coordinates from one coordinate system to another, using the Gtrans engine and translation files.
Gtrans is widely used for coordinate transformation within Sweden as it is officially recommended, translates between numerous local coordinate systems, and supports rubbersheeting transformations.
The transformation is configured by selecting a Gtrans Translation File appropriate for the Source and Destination Coordinate System. For raster features, the Reverse Translation File must be identified as well.
Output features’ coordinate system will show as Unknown, as these features no longer have an FME coordinate system tag. If the output coordinate system is known to have an exact match in FME’s coordinate system library, it can be tagged manually with a CoordinateSystemSetter.
Translation Files
A selection of Gtrans Translation Files are provided with FME.
Only reprojections defined here or with a user-provided Gtrans Translation File (see below) may be performed with this transformer.
|
File Type |
Description |
Location |
|---|---|---|
|
*.tf, *.tfi |
Translation File - a text file containing parameters defining a reprojection from one coordinate system to another.
|
[FME Install Directory]\Reproject\Gtrans\Sys |
|
*.tr1, *.tr2 |
Triangulation File - a binary file used for the interpolation of residuals.
|
[FME Install Directory]\Reproject\Gtrans\Sys |
Each *.tf/*.tfi file corresponds to a line item in the Gtrans Translation Files library accessed in the parameters dialog.
Note that when using the Filter option, FME searches the file names of the *.tf/*.tfi files - not the Source and Destination Coordinate Systems.
Geoid Files
When reprojecting between geoids, this transformer needs additional resource files.
|
File |
Description |
Location |
|---|---|---|
|
geoid.def |
Geoid Definition File - a text file containing parameters describing geoids. A default version is provided with FME. User-provided geoids may also be used - see below. |
[FME Install Directory]\Reproject\Gtrans\Sys |
|
*.grd |
Binary Grid files for specific geoids. |
[FME Install Directory]\Reproject\Gtrans\Sys |
Gtrans User Data
Users may provide their own transformations and definitions by placing the appropriate files as directed:
|
File(s) |
Description |
Location |
|---|---|---|
|
*.tf, *.tfi |
Translation File - a text file containing parameters defining a reprojection from one coordinate system to another.
The Translation File should reference the correct geoid.def and any required *.bin files. User-defined translations are placed in the same location as the provided Translation Files. |
[FME Install Directory]\Reproject\Gtrans\Arkiv |
|
geoid.def |
Geoid Definition File - a text file containing parameters describing geoids. A default version is provided with FME. The user version of this file is placed in a different location than the default geoid.def provided with FME. |
[FME Install Directory]\Reproject\Gtrans\Arkiv |
|
*.bin |
Binary Grid files for specific geoids. |
[FME Install Directory]\Reproject\Gtrans\Arkiv |
Rasters
Additional parameters are available for raster features, specifying how the reprojected cells are to be interpolated. Both the forward and Reverse Translation Files for the reprojection must be provided.
This transformer is not affected by raster band and palette selection.
Examples
Usage Notes
- FME has a Workspace Parameter, Reprojection Engine, that may be set to either FME (CS-Map) or Esri. This transformer will override this parameter setting.
- The Reprojector provides similar functionality, and will use the default library (CS-Map or Esri) set in FME. It supports some Swedish coordinate systems, but will not use the Gtrans definitions or reprojection engine.
- To reproject coordinates stored as attribute values, consider using the GtransAttributeReprojector.
Working With Coordinate System Transformers
FME inherently supports coordinate system transformations and reprojections.
Configuration
Input Ports
Output Ports
Parameters
Editing Transformer Parameters
Transformer parameters can be set by directly entering values, using expressions, or referencing other elements in the workspace such as attribute values or user parameters. Various editors and context menus are available to assist. To see what is available, click 
beside the applicable parameter.
For more information, see Transformer Parameter Menu Options.
Reference
|
Processing Behavior |
|
|
Feature Holding |
No |
| Dependencies | Gtrans software and Translation Files, included with FME. |
|
Operating System Restrictions |
Windows only. |
| Aliases | |
| History |
FME Community
The FME Community has a wealth of FME knowledge with over 20,000 active members worldwide. Get help with FME, share knowledge, and connect with users globally.
Search for all results about the GtransReprojector on the FME Community.
Examples may contain information licensed under the Open Government Licence – Vancouver, Open Government Licence - British Columbia, and/or Open Government Licence – Canada.
Example contains data © OpenStreetMap contributors.
Keywords: SWEREF99 "National Land Survey of Sweden" Sweden