We will import one of the MasterMap samples provided by the OS on their website at The example is a map of Birmingham that is provided as an "initial data" file and as a "change-only" update file. The update files will be processed in order from top to bottom, so arrange the list in the order desired using the Move buttons in the dialog's toolbar. Using the New button, add as many update files are desired. If one or more update files are to be processed, click on the New button in the dialog's toolbar and in the resulting Append dialog double click on the desired update file. It is checked by default since MasterMap is the only known significant collection of files in GML format.Ĥ. If importing UK Ordnance Survey MasterMap files, make sure the MasterMap data box is checked. The Import GML Data Set dialog will pop open to allow specification of any update files to be processed as part of the import. In the Import dialog choose GML files in the Files of type box and browse to the folder containing the GML file to be imported.
gml file can contain both an original version as well as subsequent updates.Ģ. gml files can contain a complete version of a drawing or it can contain updates to a drawing that represent changes to be made.
One interesting aspect of GML format is that a. Manifold's GML importer supports object versions and will import any metadata as a Manifold comments component. Manifold will automatically import either type and will apply any updates specified. GML files can occur in both independent and topological polygon forms. gml extension or, as is the case with some Ordnance Survey (OS) data files with no extension. expects to work closely with the OS to assure increasing compatibility with OS usage of GML. The Manifold GML importer is therefore an importer for Ordnance Survey GML format, specifically, for OS MasterMap data products. GML is currently used by the UK's Ordnance Survey (OS) for publishing MasterMap data products, the only concrete form of GML that is currently used to publish a significant amount of data. Besides the intrinsic incompatibility designed into GML, the main problem with GML is the extreme inefficiency of the format: GML will frequently require files that are over 100 megabytes in size to store GIS data that other formats can save in only five megabytes. Unfortunately, GML is something of a non-standard since every implementation of GML to date for saving GIS data has been incompatible with other implementations. GML is an abbreviation for "Geography Markup Language." A spectacularly inefficient format, GML is based on XML and is being touted as a proposed standard in some circles.
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