Today I noticed my drone refusing to go as high as I wanted, definitely nothing like 400’ or 120m. However looking at the EXIF of the photos, the altitude is shown as 117m or similar. Is it possible that these altitude settings are taken as absolute, above sea level, rather than height above the ground or above take off height?
In this case takeoff altitude is already around 100m, so if the drone uses sea level figures it would only be prepared to climb 20m. And the default RTH altitude would be 70m underground!
Thanks, Tony S
Not sure what the EXIF references in this instance, but if you want to check and compare, use the altitude values from the flight log from that particular flight and you should be able to correlate which it is.
Thanks. I’ve concluded the EXIF altitudes are meaningless. In actual fact my takeoff location is 190m ASL in any case. Lower down in the EXIF there’s another variable “drone-dji:RelativeAltitude” which assuming it’s in metres corresponds pretty well with the flight logs “IMU Altitude”. That parameter starts at zero, so I assume it’s height relative to take off location (ie more or less height above the ground, give or take).
It cannot be Sea level as I live approximately 1000ft above sea level and regularly fly off the top of the mountains in front of and behind my home which is much higher. I understood it to be relative to your take off point. Some fliers have come unstuck where they have taken off with lets say 150ft RTH setting, then flown up and over a high ridge and when executing an RTH if the part they are flying over is say 200ft higher than the take off point, the drone drops down to 150ft (the set RTH height) and ploughs into the ground.
Hope this makes sense.
Assuming his max altitude was set to a limit of 120m…
In this case takeoff altitude is already around 100m, so if the drone uses sea level figures it would only be prepared to climb 20m.
The Mini records its takeoff location as zero altitude. Every height is measured relative to that reference point using the barometric altimeter. If you take off from the top of a cliff, and descend into the valley below, the altitude will be displayed as negative.
Some fliers have come unstuck where they have taken off with lets say 150ft RTH setting, then flown up and over a high ridge and when executing an RTH if the part they are flying over is say 200ft higher than the take off point, the drone drops down to 150ft (the set RTH height) and ploughs into the ground.
If the RTH height is configured to 150ft, the drone will climb to that height before turning for Home. If the drone is already at a height greater than 150ft, then it will turn for Home at its current height. The Mini never descends to its configured RTH height.
In your example, with a 150ft RTH height, if someone sends their drone up to 200ft and then loses signal, it would simply return at 200ft. The danger would be if someone sent their drone over a 200ft ridge peak, then descended behind that peak and lost signal. If the drone was anywhere higher than the set 150ft RTH height when it lost signal, it would just turn around and head for Home at its current height. Or if it was lower than 150ft when it lost signal, it would climb only to 150ft before turning for Home. In that case it would not clear the 200ft ridge peak, and bad things would happen.
You may have misunderstood the original question. Your description is correct, however. The question was in reference to the EXIF data as it applies to altitude.
We still haven’t answered the original issue of why Griffon’s drone refused to go as high as he wanted. I understood he later tried to use the EXIF data of the photos to determine the actual height at which the photos were taken.
I don’t know anything about EXIF data, but I do know the drone does not use sea level for its height measurements.
I was able to analyse the flight log and it contains the warning … “DFlight altitude restricted. Log in or go to real-name authentication.”
This seems to be a known issue, with various different ways of getting around it, some say you need to log out and back in (not helpful if it happens when you don’t have Internet access), and some say to put your phone into aeroplane mode. Anyway it seems clear that when this bug hits, the drone is limited to 30m height.
Nobody seems to know what “real-name authentication” means.