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NEXTMap BritainNEXTMap Britain consists of a family of Digital Elevation Models (DEMs) captured and processed using the latest airborne radar technology (IfSAR) that models the ground surface in great detail. With a minimum size of half a kilometre, NEXTMap Britain provides engineers, environmentalists and may other professionals using landscape models with the most accurate,NEXTmap Britain is a complete height database of England, Wales and Scotland convenient and affordable height data solution available today. There are two basic DEMs. The Digital Surface Model (DSM) is derived from radar signals bounced off the first surface encountered. This will include forestry and other vegetation, buildings, roads and other surface structures. The Digital Terrain Model (DTM) is a representation of the earth's surface with vegetation, buildings and other cultural features removed, revealing terrain characteristics that might otherwise be masked in the DSM. The elevation calculation is made every 5 metres (known as post spacing) but it has been resampled to be available at 10 and 50 metres too. From the South East up to the Midlands, covering many urban areas including the Thames basin, the data was captured as a Digital Surface Model (DSM) with an accuracy of 50cm. The DSM for the rest of England, Wales and Scotland was collected with a vertical accuracy of 1m. A digital orthorectified radar image (ORI) dataset is also available providing a highly detailed greyscale image of the earth's surface.
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