25cm LIDAR Digital Terrain and Digital Surface Model

Light Detection and Ranging (LIDAR) is an airborne mapping technique, which uses a laser to measure the distance between the aircraft and the ground. Up to 100,000 measurements per second are made of the ground, allowing highly detailed terrain models to be generated at spatial resolutions of between 25cm and 2 metres. The Environment Agency's LIDAR data archive contains digital elevation data derived from surveys carried out by the Environment Agency and represents over 10 years of survey work carried out by a specialist remote sensing team based in Bath and Coventry. Accurate elevation data is available for approximately 50% of England and Wales. Some areas are available at 25cm resolution and these can be supplied as a combined Digital Surface Model produced from the signal returned to the LIDAR (which includes heights of objects, such as vehicles, buildings and vegetation, as well as the terrain surface) and Digital Terrain Model (a "bare earth" model with surface objects filtered out of the DSM by applying bespoke software techniques).