Description
This transformer converts coordinate system strings between different representations. It can be used to convert between an FME coordinate system name and:
- Autodesk Well Known Text (WKT)
- An EPSG number
- ESRI Well Known Text (WKT)
- A MapInfo coordinate system statement
- OGC Well Known Text (WKT)
- An Oracle SRID number
- a PROJ.4 string
This can be used in conjunction with the
CoordinateSystemFetcher and
CoordinateSystemSetter to use externally defined coordinate systems with FME features within the transformation environment. This can help FME recognize coordinate system definitions that are not currently referenced in our own system.
Note this simply converts the coordinate system name, it does NOT reproject or change your data in any way.
Example
The attached workspace shows an example use of the
CoordinateSystemDescriptionConverter transformer.
In this example we have an ESRI dataset with a coordinate system which FME does not recognize.
Looking inside the PRJ file we can see the definition is so:
PROJCS["PCS_Lambert_Conformal_Conic",
GEOGCS["GCS_North_American_1983",
DATUM["D_North_American_1983",
SPHEROID["GRS_1980",6378137.0,298.257222101]],
PRIMEM["Greenwich",0.0],
UNIT["Degree",0.0174532925199433]],
PROJECTION["Lambert_Conformal_Conic"],
PARAMETER["False_Easting",6200000.0],
PARAMETER["False_Northing",3000000.0],
PARAMETER["Central_Meridian",-91.86666666666666],
PARAMETER["Standard_Parallel_1",49.0],
PARAMETER["Standard_Parallel_2",77.0],
PARAMETER["Latitude_Of_Origin",63.390675],
UNIT["Meter",1.0]]
To find out what FME thinks the coordinate system represents, let's use the CoordinateSystemDescriptionConverter transformer in a workspace.
Workspace Screenshot
This workspace - which I obtained from one of our developers - will tell me what the FME equivalent to this unknown coordinate system is:
- The workspace simply creates a single feature with the
Creator transformer and adds the ESRI definition from the PRJ file as an attribute.
- Then the CoordinateSystemDescriptionConverter transformer converts that from the ESRI WKT to an FME Representation
Above: The CoordinateSystemDescriptionConverter parameters dialog
- Finally we set the FME representation as the new coordinate system and output the data to the Visualizer.
Above: The FME view of this dataset
So FME defines this as _FME_0, meaning it is not recognized. OK, we knew that, but click the [...] icon and you get a full description of the coordinate system:
Above: FME's definition of this coordinate systemCustom Coordinate System Definition
Now, if I want to add this coordinate system to FME, so that it is automatically recognized, then all I need to do is copy the FME definition into the
MyCoordSysDefs.fme file.
Above: The definition copied into the file
...and now I need to clean it up by:
- Removing the ESRI WKT (which I don't believe is needed)
- Adding a continuation character after each line (except the last)
- Changing the header from CS_NAME to a proper COORDINATE_SYSTEM_DEF line
- Remove all the unnecessary : (colon) characters
Above: The edited definition
Re-run the workspace and the output looks like this:
Above: Hurrah! FME now recognizes my coordinate systemÂ