Lidar Digimap FAQs


Why doesn't the Lidar data cover the full tile?

The availability grids in Lidar Download show all the OS tiles where there is some Lidar data available, however the actual Lidar data may not cover the full tile. For example you may download a tile of Lidar data that only contains a small area of actual Lidar data, and the rest of the tile is blank/empty. The tile below shows the OS 5km x 5km grid in red with a tile of Lidar DTM data beneath. Note that there is no Lidar data for the south east corner of the tile.

What is the difference between the Digital Terrain Model (DTM) and the Digital Surface Model (DSM)?

The two images below show Aberystwyth harbour, boats, cars, and buildings are all visible in the DSM on the left, but these features are absent in the DTM, shown on the right hand side.

Aberystwyth harbour DSMAberystwyth harbour DTM

What projection is the data in?

The data is provided in the British National Grid projection system but is not supplied with projection files so you may need to manually set the projection in your GIS/CAD application.

How do I view Lidar data in a GIS package?

Links to a number of online tutorials and resources are provided below:

Is there any way to view the availability of the different Lidar datasets?

In Lidar Download the Show Availability button on the Product Information popup allows you to see the extents of each dataset:

Lidar availability grid

The availability grids can also be turned on/off through the Show Availability Grid panel on the right side of the map window.