Reprojector

Reprojects feature x and y coordinates from one coordinate system to another.

Typical Uses

Performing simple reprojections, without z value handling.

How does it work?

The Reprojector receives vector, raster, or point cloud features and reprojects their x and y coordinates from one coordinate system to another, generally using the FME (CS-Map) library.

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.

The Source Coordinate System may be either read from the input feature or specified explicitly, and the Destination Coordinate System must be specified. Both may be set by selecting from the Coordinate System Gallery or by name via an attribute value or user parameter.

The Reprojector does not reproject z values.

Dynamic Coordinate Systems

Features may be reprojected to a dynamic Destination Coordinate System - that is, a local coordinate system that is created specifically for each individual feature. This is often used for tasks such as taking measurements or creating geometry in meters or other ground units, on data with geographic (latitude and longitude) coordinates.

There are two types available:

_AZMEA_ (Dynamic Reprojection Equal Area) - Better for preserving area accuracy
_AZMED_ (Dynamic Reprojection Equal Distance) - Better for preserving distance accuracy

In either case, the input feature is reprojected to a local coordinate system centered on its bounding box. Though all the output features will be centered on a common origin (with the exception of features located very near the poles) and appear stacked on top of each other, each one retains the specifics of its reprojection (and so original position), and can be safely reprojected back into a projected or geographic coordinate system.

Note that Z values are not considered, so areas or distances are best preserved for geometry at an ellipsoid height of 0 meters.

Note: To calculate and reproject to a single AZMED or AZMEA coordinate system that encompasses all input features, consider using the CommonLocalReprojector.

Rasters

Additional parameters are available for raster features, specifying how the reprojected cells are to be interpolated.

This transformer is not affected by raster band and palette selection.

Examples

Usage Notes

This transformer does not alter z values. For vertical handling, consider using a CsmapReprojector.
For finer control, including Geographic Transformation selections, consider using a CsmapReprojector or EsriReprojector.
Some geographic areas have their own reprojection libraries and transformers. See Working with Coordinate System Transformers below.
This transformer operates on features with geometry. To reproject coordinates stored as attributes, see the AttributeReprojector or CsmapAttributeReprojector.

Working With Coordinate System Transformers

FME inherently supports coordinate system transformations and reprojections, using the CS-Map coordinate system library.

Coordinate System Support and Reprojection

Coordinate systems generally have a name and a definition, and the syntax of that definition can vary greatly between both spatial data formats and other coordinate system libraries. Custom and local coordinate systems can also be defined in FME, further complicating matters. For in-depth information, see the Working With Coordinate Systems documentation.

Coordinate System Support

These transformers perform various coordinate system-related tasks, but do not reproject the data. If a coordinate system library is required for a task, CS-Map is used.

CoordinateSystemDescriptionConverter	Converts coordinate system names and definitions between FME’s internal format and common third-party and open source representations, storing the results as an attribute.
CoordinateSystemExtractor	Retrieves the FME coordinate system name of the feature into an attribute.
CoordinateSystemRemover	Removes the coordinate system from features, without modifying geometry or coordinates.
CoordinateSystemSetter	Assigns a specified coordinate system to features, without modifying geometry or coordinates.
LocalCoordinateSystemSetter	Assigns a specified local coordinate system to features, without modifying geometry or coordinates.

Coordinate System Reprojection

Different coordinate system libraries (engines) not only contain coordinate system definitions, they also have unique reprojection algorithms. FME’s generic reprojection transformers, in the first table below, use CS-Map. A selection of other libraries is also available, some of which are specific to certain areas of the world or certain software platforms.

Default reprojections, as in a workspace with different input and output coordinate systems selected, are performed with the CS-Map library, also the equivalent of using the generic Reprojector transformer.

If you are reprojecting explicitly with a transformer in the workspace, using library-specific transformers is recommended. In the case of CsmapReprojector versus the Reprojector, the library is identical, but the CSMapReprojector handles vertical coordinate calculations whereas the Reprojector does not.

Generic Reprojection Transformers

		Library
AttributeReprojector	Reprojects x and y coordinates stored as attributes from one coordinate system to another.	CS-Map
CommonLocalReprojector	Reprojects one or more features to a local coordinate system centered on the bounding box containing all features.	CS-Map
ReprojectAngleCalculator	Converts a given angle from one coordinate system to another.	CS-Map
ReprojectLengthCalculator	Converts a given distance from one coordinate system to another.	CS-Map
Reprojector	Reprojects feature x and y coordinates from one coordinate system to another.	CS-Map

Library-Specific Reprojection Transformers (Recommended)

		Library (External Links)
CsmapAttributeReprojector	Reprojects x, y, and optionally z coordinates stored as attributes from one coordinate system to another using the CS-MAP library.	CS-Map
CsmapReprojector	Reprojects feature x, y, and optionally z coordinates from one coordinate system to another using the CS-Map library.	CS-Map
EsriReprojector	Reprojects feature coordinates from one coordinate system to another using the Esri reprojection library.	Esri
GridInQuestIIReprojector Great Britain Northern Ireland Republic of Ireland	Reprojects feature coordinates from one coordinate system to another using the Grid InQuestII reprojection library. This library allows you to use the GridInQuestIIReprojector to transform coordinates between ETRS89 (WGS84) and the national coordinate systems of Great Britain, Northern Ireland and the Republic of Ireland.	Grid InQuestII
GtransAttributeReprojector Sweden	Reprojects attributes holding coordinate values from one coordinate system to another using the Gtrans reprojection library (from the National Land Survey of Sweden), and the specified translation file.	Gtrans
GtransReprojector Sweden	Reprojects features from one coordinate system to another using the Gtrans reprojection library (from the National Land Survey of Sweden) and the specified translation file.	Gtrans
PROJAttributeReprojector	Reprojects attributes from one coordinate system to another using the PROJ library.	PROJ
PROJReprojector	Reprojects feature coordinates from one coordinate system to another using the PROJ library.	PROJ
ReframeReprojector Switzerland	Reprojects feature coordinates from one coordinate system to another using the REFRAME library. This transformer handles the usual planimetric and altimetric reference frame change for Switzerland.	REFRAME

Configuration

Input Ports

Output Ports

Parameters

Coordinate Systems

Source Coordinate System

Specify the coordinate system of the incoming features.

The default is <Read from feature>, which reads the features’ existing coordinate system(s).

Coordinate systems may also be explicitly selected from the FME Coordinate System Gallery, or provided by name via an attribute value or user parameter.

If <Read from feature> is used and an input feature has no coordinate system assigned, the Destination Coordinate System is assigned to it and no reprojection is performed.

Destination Coordinate System

Specify the coordinate system to be reprojected to.

Coordinate systems may be selected from the FME Coordinate System Gallery, or provided by name via an attribute value or user parameter.

Raster Parameters

Interpolation Type

Select a method for interpolating reprojected cell values:

Nearest Neighbor	The simplest and fastest method. Values are copied from the nearest cell.
Bilinear	Calculates a weighted average, adjusted for distance, from the four (4) nearest cells.
Bicubic	Calculates a weighted average, adjusted for distance, from the sixteen (16) nearest cells.
Average 4	Calculates a simple average from the four (4) nearest cells. Similar to Bilinear and is useful for numeric rasters such as DEMs.
Average 16	Calculates a simple average from the sixteen (16) nearest cells. Similar to Bicubic and is useful for numeric rasters such as DEMs.

Cell Size

Select a method for resizing cells:

Stretch Cells	The cell size of the raster will be adjusted to maintain the same number of rows and columns in the reprojected raster as there were in the input raster.
Square Cells	The number of rows and columns as well as the spacing will be changed to maintain approximately the same cell ground area and form square cells where the horizontal and vertical cell sizes are equal.
Preserve Cells	Like Square Cells, this option will change both the number of rows and columns and the spacing to maintain cell ground area, but will also try to preserve the original cell aspect ratio, taking into account any warping caused by the reprojection.

Tolerance (cells)

Sets the tolerance, in cells, for approximating reprojected cell locations.

Using the default value of 0.0, every cell will be reprojected.

If a value greater than 0.0 is specified, some cell locations will be approximated. The difference between an approximated cell location and the true cell location should be at most the tolerance value.

For example, if a value of 0.5 is specified, each approximated cell location should be maximum one-half of a pixel away from its true location. Increasing the Tolerance value may improve performance.

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.

How to Set Parameter Values

Using the Text Editor

The Text Editor provides a convenient way to construct text strings (including regular expressions) from various data sources, such as attributes, parameters, and constants, where the result is used directly inside a parameter.

Text Editor

Using the Arithmetic Editor

The Arithmetic Editor provides a convenient way to construct math expressions from various data sources, such as attributes, parameters, and feature functions, where the result is used directly inside a parameter.

Arithmetic Editor

Conditional Values

Set values depending on one or more test conditions that either pass or fail.

Parameter Condition Definition Dialog

Content

Expressions and strings can include a number of functions, characters, parameters, and more.

When setting values - whether entered directly in a parameter or constructed using one of the editors - strings and expressions containing String, Math, Date/Time or FME Feature Functions will have those functions evaluated. Therefore, the names of these functions (in the form @<function_name>) should not be used as literal string values.

Content Types

String Functions	These functions manipulate and format strings.
Special Characters	A set of control characters is available in the Text Editor.
Math Functions	Math functions are available in both editors.
Date/Time Functions	Date and time functions are available in the Text Editor.
Math Operators	These operators are available in the Arithmetic Editor.
FME Feature Functions	These return primarily feature-specific values.
FME Parameters	FME and workspace-specific parameters may be used.
Creating and Modifying User Parameters	Create your own editable parameters.

Dialog Options - Tables

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

Table Tools

Row Reordering

Enabled once you have clicked on a row item. Choices include:

Add a row
Remove a row
Move current row up one
Move current row down one
Move current row to top
Move current row to bottom

Cut, Copy, and Paste

Enabled once you have clicked on a row item. Choices include:

Cut a row - delete and copy to clipboard
Copy a row to the clipboard
Paste a row from the clipboard

Cut, copy, and paste may be used within a transformer, or between transformers.

Filter

Start typing a string, and the matrix will only display rows matching those characters. Searches all columns. This only affects the display of attributes within the transformer - it does not alter which attributes are output.

Import

Import populates the table with a set of new attributes read from a dataset. Specific application varies between transformers.

Reset/Refresh

Generally resets the table to its initial state, and may provide additional options to remove invalid entries. Behavior varies between transformers.

Note: Not all tools are available in all transformers.

Reference

Processing Behavior	Feature-Based
Feature Holding	No
Dependencies	None
FME Licensing Level	FME Base Edition and above
Aliases
History

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 Reprojector on the FME Community.

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