Precision Terrain Surveys have collected a unique elevation model of London.

The model has a vertical accuracy of 15cm and horizontal measurement interval of 1m, and has all been collected since February 2005 using PTS Ltd’s high performance 'Airborne Terrain Elevation Mapping Scanner' (ArTEMiS), which is operated from their twin engine survey aircraft.

The ‘near vertical’ & ‘single look’ configuration of airborne laser scanning (LiDAR) is particularly suited to gathering elevation data in dense urban environments both rapidly and at low cost. The spacing of survey lines ensures the laser pulses reaches into every corner of London’s deep urban canyons. Even next to the tallest skyscrapers of Canary Wharf, BT Tower and numerous residential tower-blocks scattered across the metropolis, measurements from ground level were captured where other airborne methods (oblique or dual-look i.e. stereo) would have failed to provide reliable information.

In addition to providing a reference benchmark and fascinating perspective of the city in 2005, clearly applications of the data are extensive. The high vertical accuracy of LiDAR, compared to other elevation models, is essential to help accurately predict flood extents that would result from decimetre changes in water levels or indeed areas at risk of flash flooding. Determining the potential accumulation of water in the vicinity of a building’s footprint enhances the risk assessment of individual structures. The height data provides the Emergency Services with rapid and accurate understanding of both terrain and buildings surrounding incident areas as well as the selection of less vulnerable access routes and suitable sites for locating emergency stores. With a more long-term view, the data can assist in the understanding of larger areas under the focus of planning and development, or for determining line of sight.

Whilst the vertical resolution is not fully portrayed in these images, the digital data can be incorporated within most common Geographic Information Systems (GIS), where retrieval of precise values is possible. Should a suitable GIS not be readily available, free viewer software will be supplied.