The Environment Agency have just made their high resolution LiDAR-derived Digital Surface Model (DSM) and Digital Terrain Model (DTM) data available under the Open Government Licence through http://environment.data.gov.uk/ds/survey
The files are downloaded as zipped archives containing ASCII format files. To create a mosaic from them I have created a script using:
- The archive reader functionality from TuiView, which can get a list of files within a zip archive and convert them to paths which can be read with GDAL using a virtual filesytem as described in an earlier post
- The ‘createImageMosaic’ function in RSGISLib to create the mosaic, changing the no data value from -9999 to 0
- The ‘assignProj’ function in RSGISLib to assign the correct projection to the mosaic
- The ‘popImageStats’ function in RSGISLib to calculate stats and overviews for fast display in TuiView and other programs
The script mosaic_ea_lidar.py is available to download and is run using:
python mosaic_ea_lidar.py -o sx36_dsm_mosaic.kea \ ~/Downloads/LIDAR-DSM-1M-SX36.zip
Multiple zip files can be passed in at once to be added to the same mosaic. The output format is set based on the output file extension.
A similar script using using GRASS through the ARSF DEM Scripts is also available to download from here. Usage is the same.