LiDAR terrain data are useful for a wide range of applications but manipulating the data can be difficult and time consuming. Terra Sulis has compiled a set of thirty LiDAR maps for the Mendip region in the West of England which are available from the map store.
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Frontispiece of map ST44 and detail of Nyland, a Duck Decoy (yes a duck decoy!), drainage ditches, lost river channels and an ancient trackway in the Somerset Levels.
Each of these maps covers a 10 km by 10 km area and is made up of one hundred EA LiDAR tiles, using the one metre resolution digital terrain model (DTM) data. The EA has filtered out vegetation and building structures to give just a terrain surface. Each PDF document contains the following maps:
- Eight maps of the area hill shaded by illumination from eight points of the compass
- An Open Street Map of the area for orientation
- A pan-sharpened Landsat 8 satellite image
Hill shading is a very useful technique for highlighting small differences in terrain height which may relate to geomorphology, geology, infrastructure or archaeology. The orientation of a given feature in relation to the direction of illumination governs whether the feature is visible or not, especially if it is represented by a small height difference. For this reason the maps include hill shading from all eight points of the compass using a standard sun elevation of 25 degrees. Flicking through them can be fascinating!
The area covered by each of the maps is shown below, each is identified by the OS Block number, e.g. ST55.
The maps are rendered to A3 format and are very detailed with consequently rather large file sizes, typically 40 – 50 mega bytes.
The Environment Agency does not yet have complete LiDAR coverage so some maps may have gaps. A notable gap is currently the plateau of the Mendips.
You can identify the location of each block below (click to enlarge) and obtain the maps from the map store.
The PDF maps are available from the map store.
