GeoConcept Map Reader/Writer

The GeoConcept® Map Reader/Writer enables FME to read and write the GeoConcept Map file format, which is the native format of GeoConcept SA’s GeoConcept product.

GeoConcept Map Product and System Requirements



Operating System


FME Desktop License

FME Server

FME Cloud

Windows 64-bit




Available in FME Professional Edition and higher







Available in FME Database Edition and higher







A GeoConcept Map file stores geometry, topology and attributes for features (or objects). A single map consists of one or more physical files, but there will be one map file that determines the “point of entry” for the reader:

File Name Extension



The GeoConcept map file

Point, text, line, and polygon geometric data can be stored in .gcm files. A .gcm file should be accompanied by a .gcr file of the same name. The polygon class also includes aggregates of polygons, and donut polygons. Each map object belongs to a class and a subclass. Together, these uniquely identify the allowable geometry and fields of a map object.

The number and type of attributes associated with each class and subclass is user-definable. All features belonging to the same class and subclass will have the same number and type of attributes (although not all of them need to have assigned values.)

GeoConcept map file features support both two- and three-dimensional geometry. All members of a class and subclass will have the same number of dimensions.

Reader Overview

The GeoConcept reader produces FME features for all feature data held in a GeoConcept map file, as well as any additional files referenced by the map file. The reader extracts features one at a time from the file and passes them on to the rest of the FME for further processing.

Writer Overview

The GeoConcept writer writes FME features to a GeoConcept map file. Because it is not possible to programmatically set or modify the precision or extents of a GeoConcept map, you must select a “template” map that will be used as a template for the destination data.

While class and subclass definitions will be deleted from the map, virtual layer information will not. In some cases this is convenient, but in others, you will have to manually manipulate the view manager to give the desired appearance.

It is typical that the data read into a new destination map will include data that lies outside the extents of the template map. To reset the extents of the map, you must:

  • Open the map in GeoConcept Expert.
  • Select File > Map Properties > Space.
  • Select recalculate to find the new extents.
  • Select << copy to copy the newly calculated extents to the map.

While it is safest to close and open the map (as specified in the GeoConcept Expert manual), it is often sufficient to simply zoom to max extents. It should be noted that the GeoConcept reader can read the data regardless of the extents of the map.

The destination map will determine the coordinate system used. Features with different coordinate systems than the destination map will be reprojected to the coordinate system of the map as long as the map’s coordinate system is recognized. A warning message will be logged if the destination map’s coordinate system doesn’t match the destination dataset coordinate system parameter.