I created a DSM from Lidar data supplied by DEFRA. It's 2014 1m - I then ran it through mosaic to new raster to join the tiles. When I try to use this in a Geodesic Viewshed I get the following warning:
Input elevation raster should have a vertical coordinate system that has heights referenced to a spheroid.
So, I am projecting the raster again, it's British National Grid - what is the suggested vertical coord system for this? Can anyone recommend any reading on this to aid selecting the right system?
Many thanks.