Geometry Concepts

Invalid, Corrupt, and Degenerate Geometries

FME manages data from hundreds of different formats, systems, and transformations. The definitions of what constitutes "valid" geometry or topology vary widely among them. FME's approach is not to force all data through one definition of geometric validity, but to store data as faithfully as possible to the form in which it is provided.

In general, transformers and writers are flexible in dealing with data of all types. Geometry is usually "repaired" automatically in some way, where required. However, this repair is not always possible. Where user intervention is required, FME offers a large selection of transformers to repair geometries that do not follow the restrictions of the format or task at hand.

Geometry Names

All geometries can have a Geometry Name. This is a string that can have an encoding, such as UTF-8 or Japanese.


All geometries can have an arbitrary number of traits. These are attributes at the geometry level, rather than the feature level. Hierarchical geometries can have separate traits at each node in the geometry hierarchy.

For example, this aggregate feature depicted in the FME Data Inspector has five traits associated with its geometry. These traits were inherited from a Trimble SketchUp reader.


Some Geometries can have measures associated with them (also known as "linear referencing" or "dynamic segmentation"). These are an arbitrary number of additional dimensions at each vertex location. These dimensions are named and must have a Real64 type value. A "default measure" is optional and not required to be named.

Other Concepts