Altitude with Georef images

Hi guys

I have a fairly stupid question.

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?

Benjamin

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.

Thanks for your answer X1Aero,

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

Benjamin

Ok, I finally got the result.

With a good AMSL value from the take-off point, using the barometer is quite accurate, but it won’t win over RTK or simple CGP