OS MasterMap® – GML

OS MasterMap® is a geographical database of the whole of Great Britain, updated up to 5000 times daily. This database contains intelligent and interfacing topographic and addressdata, imagery and the newly-launched Integrated Transport Network™ data. This pioneering and far-reaching resource includes some 440 million features, each identified by a unique number, allowing for data association. Geometric data is constructed using spatial primitives based on the ISO 19107 specification that provides spatial data providers and users with a means of defining geographic features.

Ordnance Survey makes use of only the point, linestring and polygon primitives in order to encode all of its OS MasterMap geometry. The use of such well defined geometric primitives coupled with a structured mechanism for defining features ensures that when spatial data is exchanged in GML 2.1.2 it can be interpreted and understood by everyone. Information communities can define their own features and attributes by agreeing on their own GML application schemas. OS MasterMap data is encoded using a GML application schema in order to deliver rich feature and attribute information.