Reprojects coordinates stored as attributes from one coordinate system to another using the PROJ library.

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Typical Uses

  • Reprojecting features when explicitly using the PROJ library is desired
  • Adding additional coordinate pairs as attributes, in alternate coordinate systems

How does it work?

The PROJAttributeReprojector accepts any feature. The user specifies the attributes containing x, y, and optionally z coordinates, and configures either an Automatic or Manual Transformation.

The transformer reprojects the coordinates according to these selections, using the PROJ reprojection library, and updates the x, y, and z attributes to the new values, overwriting the originals.

This transformer does not alter the feature’s geometry – only the values of the selected X and Y Attributes (if they contain coordinate values) are changed. Accurate results depend on the user’s correct specification of the source coordinate system.

FME currently uses PROJ version 9.2.0.

For Automatic transformations, the Source Coordinate System and Destination Coordinate System must be specified explicitly.

For Manual transformations, a PROJ string must be provided describing the desired transformation, as documented at PROJ’s Transformation Pipelines and shown in the examples further below. WKT2 descriptions are also valid.

Coordinate System Definitions

This transformer will accept coordinate systems defined in any one of the following forms.

Definition Style

Example: LL-WGS84 Defined

External Reference

EPSG Number


EPSG Website

Well-Known Text (WKT1 or WKT2)


DATUM["World Geodetic System 1984",

ELLIPSOID["WGS 84",6378137,298.257223563,







Open Geospatial Consortium: Geographic information — Well-known text representation of coordinate reference systems

Note that the EPSG website can also provide WKT strings for specific coordinate systems.

PROJ String

+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs

PROJ Projections

They are fully interchangeable and can be used in any combination to define the Source and Destination Coordinate System for an Automatic transformation.

They may also be used in a PROJ string or pipeline for a Manual transformation.

Note that EPSG and WKT representations can more fully describe a coordinate system than PROJ strings, and so are the preferred definition types.

Geographic Transformations and Grids

Geographic Transformations control how coordinates are converted between different datums.

For an Automatic Transformation, FME will attempt to select an appropriate transformation between the Source and Destination coordinate systems.

Manual Transformations are performed as specified in the Manual Transformation Parameters.

Grid-Based Datum Adjustments

Some areas use grid shift files for datum conversion.

Many grids needed by PROJ are included with FME, and additional grids may be downloaded from the PROJ website.

PROJ will generally search for an appropriate grid to use, although specific paths or URLS may be specified in a transformation definition.

PROJ User Data

Grids and customized proj.db files may be placed in your [FME User Directory]/ProjData folder.

Sample ProjData folder locations:


/Users/[User]/Library/Application\ Support/FME/ProjData/

Windows 10




PROJ transformers will give preference to files placed in this folder over other locations, including the proj.db and grid files shipped with FME.


Usage Notes

  • This transformer does not change the feature's coordinates – it only changes the values of the selected X, Y, and Z attributes (if they contain coordinate values).
  • Earlier versions of PROJ used the proj-datumgrid grid files package, which is still available on the PROJ website. It should be replaced by the current proj-data package.
  • 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 AttributeReprojector provides similar functionality, and will use the default library (CS-Map or Esri) set in FME. It does not handle z values.
  • To reproject coordinates stored as geometry, consider using the PROJReprojector.
  • Automatic Transformations will produce a PROJ pipeline string in the log, which can be used as a template for Manual Transformations.

Working With Coordinate System Transformers

FME inherently supports coordinate system transformations and reprojections.


Input Ports

Output Ports


Editing Transformer Parameters

Using a set of menu options, transformer parameters can be assigned by referencing other elements in the workspace. More advanced functions, such as an advanced editor and an arithmetic editor, are also available in some transformers. To access a menu of these options, click beside the applicable parameter. For more information, see Transformer Parameter Menu Options.

Defining Values

There are several ways to define a value for use in a Transformer. The simplest is to simply type in a value or string, which can include functions of various types such as attribute references, math and string functions, and workspace parameters. There are a number of tools and shortcuts that can assist in constructing values, generally available from the drop-down context menu adjacent to the value field.

Dialog Options - Tables

Transformers with table-style parameters have additional tools for populating and manipulating values.


Processing Behavior


Feature Holding


Dependencies None

FME Community

The FME Community is the place for demos, how-tos, articles, FAQs, and more. Get answers to your questions, learn from other users, and suggest, vote, and comment on new features.

Search for all results about the PROJAttributeReprojector on the FME Community.


Examples may contain information licensed under the Open Government Licence – Vancouver and/or the Open Government Licence – Canada.