KAS Software
Suppliers of map viewing and coordinate conversion software, bespoke digital maps, height data and gazetteers

KAS Software has developed a free Windows map viewing program which can be used to display, both in map view and in 3D using OpenGL, all released OS OpenData raster map data. Additionally we have developed an open specification map file format which allows the creation of composite maps containing OS OpenData products for the whole of Great Britain.
We have used this mass of OpenData™ to create our own raster & height data maps, map and postcode gazetteers. Some of these maps and gazetteers are free for download and use for any purpose consistent with the OS OpenData Licence.
In particular, all four OS OpenData™ miniscale (1:1,000,000) maps, and the 1:250,000 scale colur raster map, are available for no-cost.
The 1:25,000 scale vector map raster and the 1:10,000 street view maps covering the whole of GB are available only for a fee, because they're simply, at respectively 4Gb and 16Gb, too big for free download.
However, demo versions of these maps are available.
The OS have released ODN (Ordnance Datum Newlyn) height data covering the whole of Scotland, England, Wales, the Isle of Mann & outlying islands, evenly spaced at a resolution of one height value (pixel) every 50m, equating to 400 values per Km2, or, very roughly, 100,000,000 land height values over the area covered. Our .gdf file format was designed specifically to provide easy access to any given point withing this mass of data.
This is a variant on the long-used Tiff format which has been modified to contain geolocation information. The OS have released various scales of digital raster maps as geotiff files - these can all be read natively by our map viewing program (and viewed in 3-D if you've downloaded our free GB height data).
The OS have provided gazetteer information of a variety of detail, ranging from the 1:250,000 scale colour raster map gazetteer with around 25,000 entries, the 50k scale gazetteer which contains around 250,000 entries, a the full postcode database which maps postcodes with OSGB location and cotains well over 1,000,000 entries. We've taken this data and created our own gazetteer format which integrates fully with MapView to give a fully searchable database of GB localities.