Lidar Digimap offers detailed Lidar data from the Environment Agency through a convenient, on-demand web interface. It also offers vertical aerial photography.

Lidar data is a very accurate model of the earth’s surface. The data is captured by firing very rapid laser pulses (thousands of times per second) at the ground surface. By examining the laser energy reflected back from the ground the surface is captured as a dense cloud of 3D points. These points are then converted in to highly detailed terrain models of the surface of the earth and by examining the reflections from both the ground surface and the vegetation canopy it is possible to derive both Digital Terrain Models of the bare earth surface (DTM) and also Digital Surface Models (DSM) that show the vegetation canopy.

Vertical aerial photography is an airborne mapping technique, which uses a high-resolution camera mounted vertically underneath the aircraft to capture reflected light in the red, green, blue and for some datasets, near infra-red spectrum. Images of the ground are captured at resolutions between 10cm and 50cm, and ortho-rectified using simultaneous LIDAR and GPS to a high spatial accuracy. The Environment Agency has been capturing vertical aerial photography data regularly since 2006. Vertical aerial photography has been captured on a project by project basis each ranging in coverage from a few square kilometres to hundreds of square kilometres. Historic data are available for some areas where we have carried out repeat surveys. Photography can be captured in all survey conditions, including incident response where it is used to derive flood outlines. The photography is supplied as a raster dataset in ECW (enhanced compressed wavelet) format as either a true colour (RGB), near infra-red (NIR) or a 4-band (RGBN) dataset.

Uses of Lidar data are highly varied, from use in the creation of visual effects for virtual reality and film projects to archaeology, forestry management, flood and pollution modelling. Because it is so much more detailed than “traditional” digital terrain models, in some datasets down to 25cm resolution, there is a wealth of additional uses for the data. Looking at lines of sight for rural developments, mobile phone and wireless broadband signals amongst other things is easier and more accurate using Lidar data because of the inclusion of vegetation in the model.

All the Lidar data included in Lidar Digimap is available under the Open Government Licence, and access is provided for free with a subscription to Aerial Digimap.