25cm Composite LIDAR 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. LIDAR JPEG Images are geo-referenced, coloured, shaded relief images that contain valuable information on terrain elevation and objects contained within the landscapes covered. The images are colour coded for elevation, these colours are uniform across the country, and as such elevation contours can be derived from the data. The contour values that could be extracted are: -8, -6, -4, -2, 0, 5, 10, 20, 35, 50, 75, 100, 150, 200, 250, 300, 400, 600, 800, 1000 and 1200 metres. The most valuable of these contours will be those around the coast - -2, 0, 5 and 10 metres. Image analysis and visual interpretation of the data can be used to derived maps of land use (such as forestry, urban, farmland, etc), and also to identify buildings, roads and other infrastructure within the landscape. The spatial accuracy and resolution of the imagery is the same as the input LIDAR data grids in this case 25cm.