A Digital Terrain Model (DTM) is a digital file consisting of a grid of regularly spaced points of known height which, when used with other digital data such as maps or orthophotographs, can provide a 3D image of the land surface. This download contains OSNI 10k sheet numbers 101- 150. This is a large dataset and will take sometime to download. Please note that this is an interpolated dataset from the OSNI Enhanced DTM from 2014-2016. The reference grid for this dataset is available here: https://www.opendatani.gov.uk/@land-property-services-ordnance-survey-of-northern-ireland/osni-open-data-coverage-grid-10k
