We have just released our latest 1m and 2m DTM Composite products on the DEFRA DSP. This includes the best available surveys captured before October 2019. With the 2019 release we have changed our data format from ASCII to GeoTiffs. These GeoTIff files are supplied in 5km tiles with elevations in metres. GeoTIFF is a modern GIS format widely used for delivering elevation data and was chosen due to its open standards and highly efficient data storage. Data volumes are on average 5x smaller, enabling faster download over internet and more manageable storage. Storing the data in GeoTiff also enables us to start to deliver more services over the web such as Image Services and WCS services. These services provide APIs for users view the data directly in a browser, or bring the data directly into desktop GIS and perform geoprocessing analysis on it. The old ASCII format meant we were limited to what we could offer. Moving to GeoTiff format also aligns the Composite product to our National LIDAR Programme products.
The vast majority of software’s including QGIS, ArcGIS, GRASS & AutoCAD Civil3D are able to open a GeoTiff file in the same way as the previous ASCII file. If you do experience any issues we have put together some links on converting between file formats on the Blogs and Guides section of our storymap. This is a straightforward conversion process in GIS software or can be achieved with a few lines of code.