FME can read files in the Geographic Data Management System (GDMS) format.
All three input file types are supported for import:
- VERTICES
- CROSSREF
- TEXTDATA
Overview
GDMS is a Wang-based mapping system used by municipalities around the world. GDMS is first-generation mapping system technology, now owned by Esri and called the Spatial Database Engine (SDE). GDMS supports several geometry types, annotation, and only limited attribution.
The GDMS File reader module provides FME with access to the three GDMS file formats known as VERTICES, CROSSREF, and TEXTDATA.
The VERTICES and CROSSREF files should be provided as a matching pair, where the VERTICES file holds the geometry of features and the CROSSREF file holds attribute information. Points, line, polygons, and donuts are contained in these files.
The TEXTDATA file holds both geometry and attributes for text annotation features. These features include text, polyline or polygon, circle, and symbol elements.
GDMS data files are binary and hold two-dimensional (2D) features.
While GDMS data sets consist of the three separate files, as described above, the precise format of these files is specified using DEF lines within the workspace.
There is no default extension that FME recognizes as a GDMS input file.
FME does not automatically translate GDMS files, as some modification to the DEF lines is required. FME does, however, automatically generate a workspace that can be used as a good starting point for customized GDMS translations.
Reader Overview
First the GDMS reader parses the DEF lines and keywords to determine the location of the input datasets, as well as their precise format. The FME then proceeds to the following two steps:
-
If no VERTICES or CROSSREF files are specified or found, this step is ignored.
The GDMS reader opens the VERTICES and CROSSREF input files and immediately starts reading from both files, using the Map Layer and Unique ID to attach attributes from the CROSSREF file to the VERTICES appropriate features. The GDMS reader then returns these features to the rest of the FME for processing.
It is assumed that the VERTICES and CROSSREF files are both sorted by Map Layer and Unique ID before these files are passed to the FME.
Note: Features within the VERTICES may have zero, one, or more corresponding CROSSREF entries.
-
If no TEXTDATA file is specified or found, this step is ignored.
The GDMS reader opens the TEXTDATA input file and immediately starts reading features, returning them to the rest of the FME for processing.
Each returned feature has its feature type set to the geometric type of the feature, as follows: gdms_point, gdms_line, gdms_polygon, gdms_text_symbol, gdms_text_line, gdms_text_polygon, gdms_annotation.