Building Height Attribute data is derived from the latest source Digital Terrain Model (DTM) and Digital Surface Model (DSM).
For the purposes of simplifying the merging process, the individual 5 km² tiles are supplied without header information. Instructions on the merging process can be found in the Getting Started Guide.
The format and structure of the individual columns within the data will be consistent (see table below).
The Building Height Attribute header file can be downloaded from the 'Supporting documents' section of the OS MasterMap Topography Layer – Building Height Attribute Technical Information product page of the OS website.
All heights have been calculated in metres to one decimal place (decimetre).
The Building Height Attribute dataset uses Ordnance Datum Newlyn (ODN) as the national height datum for all height values across mainland Britain. Other British height datums (for example, Lerwick for the Shetland Islands) are used where applicable. All height datums are incorporated within the National Geoid Model OSGM15.
There are two resources available that will help you gain further insight into coordinate systems in Great Britain:
OS_Topo_ TOID
OS_Topo_TOID_ Version
BHA_Proces sDate
Tile Ref
AbsH Min
Abs H2
AbsH Max
Rel H2
RelH Max
BHA_
Conf