I'm trying to find carry out a viewshed analysis but am not able to get consistent results.
Having tried and failed with viewshed and viewshed2 I discovered interactive viewshed analysis in ArcGIS Pro 2.5.0. This appeared promising but having input an observer offset of 10m and using the Ordnance Survey's 50cm DSM as the ground layer I was surprised to see the viewshed change as I zoomed the camera out (using the "C" shortcut to change the cursor to explorer mode). The ground layer uses EPSG: 27700 for the coordinate system and EPSG: 5701 for the vertical coordinate system. I'd like to know why this is happening as it makes any output from this tool unusable.