FlatGeobuf Writer Parameters

The FlatGeobuf reader cannot distinguish between a null value and empty string and attribute values that were written as null may be read back as empty strings. This option will write null values as missing instead to avoid this problem.

  • Yes – Null attribute values will be written as missing.
  • No (default) – Attributes will be written as-is. Null attribute values may be read back as empty strings in FME.

Spatial

Coordinate systems may be extracted from input feature data sources, may come predefined with FME, or may be user-defined. FME allows different output and input coordinate systems, and performs the required coordinate conversions when necessary.

How FME Processes Coordinate Systems in the Workspace

If a coordinate system is specified in both the source format and the workspace, the coordinate system in the workspace is used. The coordinate system specified in the source format is not used, and a warning is logged. If a source coordinate system is not specified in the workspace and the format or system does not store coordinate system information, then the coordinate system is not set for the features that are read.

If a destination coordinate system is set and the feature has been tagged with a coordinate system, then a coordinate system conversion is performed to put the feature into the destination system. This happens right before the feature enters into the writer.

If the destination coordinate system was not set, then the features are written out in their original coordinate system.

If a destination coordinate system is set, but the source coordinate system was not specified in the workspace or stored in the source format, then no conversion is performed. The features are simply tagged with the output system name before being written to the output dataset.

For systems that know their coordinate system, the Coordinate System field will display Read from Source and FME will read the coordinate system from the source dataset. For most other input sources, the field will display Unknown (which simply means that FME will use default values). In most cases, the default value is all you'll need to perform the translation.

You can always choose to override the defaults and choose a new coordinate system. Select More Coordinate Systems from the drop-down menu to open the Coordinate System Gallery.

Changing a Reprojection

To perform a reprojection, FME typically uses the CS-MAP reprojection engine, which includes definitions for thousands of coordinate systems, with a large variety of projections, datums, ellipsoids, and units. However, GIS applications have slightly different algorithms for reprojecting data between different coordinate systems. To ensure that the data FME writes matches exactly to your existing data, you can use the reprojection engine from a different application.

Note  To use this feature, you must have a supported GIS application installed on your system (for example, Esri ArcGIS®).

To change the reprojection engine, Select Workspace Parameters > Spatial > Reprojection Engine. In the example shown, you can select Esri (but the selection here depends on your installed applications):

For more information, see the links below:
  • Dimension from First Feature – Files produced will contain geometries with dimension information obtained by the first feature observed by the writer.
  • 2D – Files produced will contain two-dimensional coordinate geometry.
  • 2D + Measures – Files produced will contain two-dimensional coordinate geometry and measures.
  • 3D – Files produced will contain three-dimensional coordinate geometry.
  • 3D + Measures – Files produced will contain three-dimensional coordinate geometry and measures.
Note  These parameters can be modified after the writer has been generated. For more information, see FlatGeobuf Writer Feature Type Parameters.

Specifies whether or not to generate spatial index files when writing FlatGeobuf files.

Note  Checking this option changes the order of features in the output file so they match the spatial index. If order is important, uncheck this option, but note that the file will not be cloud-optimized.
  • Yes (default) – The output file will contain an embedded spatial index of features. A larger file will be produced and write performance may be impacted depending on the number of features written.
  • No – An embedded spatial index will not be created in the output file, resulting in a smaller file. Note that reading these files back with spatial filtering will impact performance.