However, due to the relatively coarse nature of the grid used (50m by 50m pixels), this does carry a degree of spurious accuracy (as we are inevitably dealing with averages). The heights in Terrain 50 are recorded as floating point numbers, so apparently convey more precision than PANORAMA. A lot of data processing goes into turning raw LiDAR data into a terrain model, but this all takes place behind the scenes, so it is difficult to know exactly what has been done. This DTM was created using LiDAR data surveyed from the air and then averaged out to 50m by 50m grid cells. In July, the OS released a new product, known as Terrain 50. The heights in PANORAMA are recorded as integers, i.e. In order to turn this into a rasterised DTM, some interpolation algorithm (I don’t know which) was used to estimate elevation values between contours to result in a continuous field (50m by 50m pixels) of elevation values for all of the UK. This was created using contour data surveyed in the 1970s. Previously (and still today), the OS made available a dataset known as PANORAMA. The spur for this was the launch in July of a new DTM onto the OpenData site. ![]() ![]() This week, in an attempt to avoid any substantive work, I have been playing around with the Ordnance Survey’s Digital Terrain Models (DTM) that are available for free as part of their OpenData archive to anybody who wishes to use them.
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