Northern (65°N) Mission Altitude Error
A mission was planned by myself, though flown by an relatively inexperienced pilot with a Mavic Mini 2 in Northern Canada recently. Gridded mapping mission was all set up correctly, 40m altitude, and flight was executed seemingly successfully until I got hold of the imagery and processed it. From the processed photogrammetry I can see that the UAV did the mission at ~26m, resulting in obviously poor overlap.
Is there any reason/cause for this mistaken altitude? Could it have been pilot error in some way (I'm new to Dronelink, though I know from my DroneDeploy missions that once a user takes over input the autopilot mission is fully aborted and would need to be restarted). Could this be an issue with the high latitude?
My only thought was that the takeoff point was at a significantly different elevation, but the site is very small (120m square), flat, and the pilot was within the flight coverage area for takeoff.
Any insight or things to potentially investigate further would be much appreciated.
Comments
9 comments
Hard to tell without seeing the mission plan.
Can you share the actual mission plan?
Apologies if this isn't the right thing...let me know if there's a better sharing option
https://app.dronelink.com/graham-pope/my-first-project/plan/KmLYWkH3USXOfiONXWtx/Okhu37eY9uKhog9j3PXW
I confirmed with the (novice) pilot that he didn't have any interruptions or odd behavior that he noticed (i.e., likely not some weird input that he did)
The altitude is above the take off point not above ground level, so from reading your post if the images are showing an AGL height of ~26M then increase the plan height to 54M ATL and refly it
I mean...that's a bandaid to the problem that only works if we catch this and have the ability to re-fly. I'm more concerned as to why a mission set at 40m above takeoff point flew at only 26m above takeoff point?
i reckon the figure of 26m is AGL not ATL, where are you getting that 26m figure from, can you share the flown mission, is the take off location in a dip or on a hillside
I got 26m from photogrametrically processing the imagery and using that data; cameras are ~26m above ground surface. Also, just the fact that my expected 75/70 overlap looks more like 25-30% based on my coverages, the UAV was way too low.
I think that I'm just going to have to do some testing to see if I can replicate this, even though an initial test flight before sending the UAV to the field (with the same mapping specs) worked just fine. I know others have run into issues with Northern flights (compass errors, etc), and I don't know if there's any reason that the program would start to behave oddly at higher latitudes. I don't see why it would...app told it to climb 40m from takeoff point, and it climbed just over half of that.
If the mission was started immediately after takeoff, that is concerning and I would be interested to see if you can reproduce it. If it was started while the drone was already in the air for some time, it is possible for the barometric altimeter to drift by many meters.
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