LiDAR (light detection and ranging) is a relatively new method of surveying landscapes in great detail. It involves flying over a landscape and sending down laser pulses – the time taken for a laser pulse to be reflected back builds up a 3D picture of the relative height of the land and vegetation below. Known as a dot cloud, these reflection points can be processed to form an incredibly accurate and detailed computer model that can be viewed in many ways.
Due to the nature of the laser beam, which can send out more than 300,000 pulses per second, LiDAR is able to penetrate woodland more than other forms of remote sensing or ground survey and thus gives us the opportunity to “see through the canopy” to a hidden world.
As part of the Breaking New Ground (BNG) Landscape Partnership Scheme, the Forestry Commission and Forest Research set out to survey a 150km2 of the Thetford Forest and Kings Forest areas in the Brecks to determine what lies underneath. In comparison to the intensively farmed land around it, the forest is thought to have had a relatively benign effect on surviving ground features and it was hoped that these areas would prove to be a rich source of evidence from thousands of years of previous land use.
These images show three pictures; the first is a conventional aerial photograph of the West Tofts Heath area. Second is a LiDAR image showing ground cover coloured according to height, a potentially very useful land management tool. The third is an amazing LiDAR image in which the tree cover has been digitally removed, and the ground contours coloured to highlight features on the ground.
This type of imaging provides an incredibly detailed relief of the ground features and clearly reveals the extent and survival of the earthworks.
At the start of the project no-one had imagined that the LiDAR data would discover the sheer volume of the features revealed through this process, and discussions are now starting to determine how BNG and its project partners can make the most effective use of the new data available.
The LiDAR project links to all BNG projects that include an element of landscape interpretation, such as The Brecks from Above; Flint in The Brecks; Brecks’ Warrens and Lodges; Sheep in The Brecks; and Brecks’ Military History.
If you would like to use the LiDAR data yourself, please get in touch with us by emailing firstname.lastname@example.org.