FlatGeobuf Format Attributes (Feature Representation)

In addition to the generic FME feature attributes that FME Workbench adds to all features (see About Feature Type Attributes), this format also adds format-specific attributes (Format Attributes).

FlatGeobuf features consist of geometry and a set of user-defined attributes.

Geometries are 2D, with optional Z (3D) and measures (M).

Note Features within the same file are all of the same dimensionality, that is, within a file, either all geometries have Z values or no feature has Z values. Mixing 2D and 3D features or 3D and 2DM features is not permitted.

A FlatGeobuf file defines a set of features that may contain mixed geometry types with the same dimensions (2D, 2D+Measures, 3D, or 3D+Measures) and share the same list of user-defined attributes. The values of the user-defined attributes can vary from feature to feature within the same FlatGeobuf file. The names of the user-defined attributes for an individual FlatGeobuf file are specified in the feature type parameters for that FlatGeobuf file. The feature type of a FlatGeobuf feature is the same as the baseName specified in the feature type name.

The underlying storage of FlatGeobuf does not distinguish between a null attribute value and an empty string, but can write missing values. Use the Convert Null Attribute Values to Missing writer parameter, or a NullAttributeMapper transformer if the empty string values are undesired. On read, those attribute values will be read as missing; use a NullAttributeMapper transformer after the reader to convert to null values if desired.