Working with GML
The Open Geospatial Consortium, Inc.'s (OGC) Geography Markup Language (GML) Encoding Specification is a standard protocol for expressing geographic features, their geometries, and attributes using XML. GML has two key parts: an application schema that describes the GML document and the document that contains the actual data encoded using XML.
GML is a mechanism for encoding almost any geospatial schema. This capability supports the need for an organization to publish its own information model regardless of whether it is simple, rich, or somewhere in between. It was designed to be broad and cover many needs. For example, the GML 3 specification describes close to 1,000 tags (named objects) and incorporates a number of potential geometry types for describing features. These include simple or aggregate features, circular and elliptical arcs, 3D, topology, rasters, sensor feeds, metadata, and time-based features.
Working with GML datasets in ArcGIS
To use GML datasets in ArcGIS you must install the ArcGIS Data Interoperability extension for Desktop from the ArcGIS installation media. Any place where you can specify a data source, you can use a GML dataset, such as adding data to ArcMap or as an input feature with a geoprocessing tool.
Possible uses include the following examples:
- Adding GML features directly to ArcMap
- Using GML data as input to a geoprocessing tool and generating results as a GML dataset
- Converting other GIS formats to GML
- Using GML data in ArcGlobe
- Publishing GML data as a WFS service in ArcGIS for Server
Using the ArcGIS Data Interoperability extension for Desktop
The ArcGIS Data Interoperability extension for Desktop is based on Safe Software's FME technology.
The GML simple features (GML-SF) profile
Installing the ArcGIS Data Interoperability extension for Desktop gives you immediate access to GML-SF datasets. You can use interoperability connections to add GML-SF features to maps, use them with geoprocessing tools, and use conversion tools in the Data Interoperability toolbox to import and export GML-SF datasets.
Esri recommends using the GML-SF profiles where possible because it supports the open exchange of GIS information. The GML Simple Features profile was designed as a common format for interoperability by many GIS software organizations committed to providing open GML support.
ArcGIS can read and write GML 3 using the GML Simple Features profile. See Using GML simple features for instructions.
GML application schemas
GML application schemas and profiles are extensible and can be customized to support data interoperability within a specific community of interest. Purchasing a ArcGIS Data Interoperability extension for Desktop license and enabling the extension adds additional out-of-the-box support for several widely used GML application schemas. The ArcGIS Data Interoperability extension for Desktop also includes FME Workbench and support for hundreds of GIS, CAD, raster, and database formats and schemas.
If your GML application schema or profile is not supported out of the box, you can add support for new GML formats using FME Workbench. See Adding new GML application schemas.