CsmapAttributeReprojector

Reprojects coordinates stored as attributes from one coordinate system to another using the CS-MAP library.

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Typical Uses

• Reprojecting coordinates stored as attributes when explicitly using the CS-Map library is desired
• Reprojecting coordinates stored as attributes with Z values
• Performing reprojections with finer control than the AttributeReprojector transformer provides

How does it work?

The CsmapAttributeReprojector accepts any feature. The user specifies attributes containing X, Y, and optionally Z coordinates, and supplies both the Source and Destination Coordinate Systems.

The transformer reprojects the coordinates according to these selections, using the CS-Map library, and updates the X, Y, and Z Attributes to the new values. The original values are overwritten.

This transformer does not alter the feature’s geometry – only the values of the selected X, Y, and Z Attributes (if they contain coordinate values) are changed.

Accurate results depend on the user’s correct selection of the source coordinate system.

The CS-Map library is FME’s default library, and so is generally used for most transformations. Using this transformer explicitly ensures that this library is used, and also provides options for handing Z (vertical) 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.

Geographic Transformations

Geographic Transformations control how coordinates are converted between different datums.

The default Transformation is <Auto> (or blank), which will look for an appropriate transformation between datums, if one is needed.

If an explicitly selected pair of coordinate systems has one or more geographic transformations available, they will be provided for explicit selection.

If set to <None>, the NULL_FME transformation will be used which does not alter the value of any coordinates.

Examples

Usage Notes

• FME also 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.

Working With Coordinate System Transformers

FME inherently supports coordinate system transformations and reprojections.

Configuration

Input Ports

Output Ports

Parameters

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.

Reference

Processing Behavior	Feature-Based
Feature Holding	No
Dependencies	Some reprojections may require additional grid files.
Aliases
History

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