Converts a given length from one coordinate system to another.

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Typical Uses

  • Determining text heights and widths
  • Reprojecting distances stored as attribute values

How does it work?

The ReprojectLengthCalculator receives features with geometry and reprojects a given distance from one coordinate system to another.

The transformer starts with two points. One is the first coordinate of the input feature’s geometry, and the second is calculated from that point using the Original Line Angle and Original Line Length. Both of these points are reprojected from the Source Coordinate System to the Destination Coordinate System. A new length is calculated from the reprojected points and added to the output feature as an attribute value.

Original Line Length is in the Source Coordinate System’s ground units. The length may be provided as an attribute, expression, constant, parameter, or conditional value.

The Original Line Angle may be provided as an attribute value, constant value, expression, user parameter, or conditional value.

Both the Source and Destination Coordinate Systems must be specified explicitly.

Reprojections are generally performed using the FME (CS-Map) library, however, this transformer will honor the Workspace Parameter Reprojection Engine, and will use the Esri Reprojection Engine if it is selected there, with or without an Esri product being installed.

Z values are not supported.

This transformer assumes all coordinate systems are Cartesian.


Usage Notes

  • This transformer requires that features have geometry to provide an initial coordinate. Non-spatial features will not produce valid output. To create geometry for non-spatial data with coordinates as attributes, consider using a VertexCreator.
  • To calculate the reprojected length of a feature with line geometry, consider using a Reprojector (or other reprojection transformer) and LengthCalculator.

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

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