When I am Geo-referencing my images with MP, if I use AMSL it will output the GPS altitude and if I unchecked it and enter the AMSL of my base or arming point, it will be using the barometer data, Am I wrong?
I thought it would use the relative altitude from the arming point. Could be wrong, but I remember seeing my maps like 300m below the actual elevation when this was unchecked. That was years ago though.
I was able to get my hand on some Lidar DEM and check a couple of location with the barometer on my phone, calibrated with the QNH I got from the local airport ATIS, it’s not really perfect because QHN is given without decimal, so 1 hPa is 28 feet, that a pretty big margin of error…
Right now with the AMSL option checked and no GCP, the altitude given is rubbish.
But either way, I know the altitude of the arming point so I will compare both result and come back to you guys