Hello. It appears that there is a difference of about 10 meters in the reported ground altitude in SRTM date and google earth with the altitude reported by GPS at this location. So when the aircraft is on the ground it says AGL 10 and exported kml shows the path 10 meters above ground in Google Earth.
I have read the code for NavSetGroundReferenceHere flight plan command and it seems it makes the aircraft take the current GPS altitude as ground level which seems a good thing. However this does not fix things in the GCS.
How is the AGL shown in GPS calculated?
How can I make it not use SRTM data?
How can I can I tell what the aircraft thinks the ground level is ?
And what is the ground_level parameter in flight plan for?
Thanks for the help.