I don't know how to convert the data from ATDI.
But you can download the data from UK gov for free directly.
DTM data (50m down to 50cm)
https://www.ordnancesurvey.co.uk/ope.../products.html
http://environment.data.gov.uk/ds/su...rvey?grid=TQ27
Clutter data (25m)
https://catalogue.ceh.ac.uk/download...terface=:2::::
Building Outlines
Currently only from OpenStreetMap.
If you have a specific area you want to use, I can help.
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