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Low altitude mission flight with litchi. Altitude problems

Nora

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Hello all,

I have a problem.
I have a Mavic 2 enterprise (Zoom) and I´m trying to fly a low altitude mission planned in Litchi with 99 waypoints covering an area of 100x400m about 100m away from my position with a flight altitude of 3m.
I use the online elevation model and checked "above ground" for all waypoints. Also the first waypoint is directly next to the take off point.

The drone maintains altitude relatively well at first, but after about a third of the mission the drone begins to climb to 5-6 m or higher. This happens at different locations with different elevation profiles. Even over very flat areas.

Does anybody have an idea how to solve this problem?
Or can anybody recommend a different flight planning software for low altitude flights? Also we need to fly really slow (1,8 km/h).

Thanks a lot
 
I'm not sure what, exactly, might have caused the issue with the flight that you mentioned, but you are expecting far too much vertical accuracy. Combining with errors in the DEM used to compute the altitude profile with drift in the barometric height measurement as the flight progresses, you should not expect better than 5 meters height accuracy relative to the ground.
 
To continue your question from your original post here:

You are aware that flying that low results in an enormous amount of images taken?
If you are @ 5m and flying at 1 m/sec with a focal length 48mm you are creating ~11.100 images (at 75% / 60% overlap with a GSD 01. px/cm)

I never have to fly that low when using the images in agriculture postprocessing (NDVI output)
 
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Then go for following flight control apps:

- Dronelink
- UgCS

(both are DEM aware)

The best of those 2 is definitely UgCS.
 
I was just looking at the UgCS software and thinking about using this one. ;-) Good to know you recommend this one as well !
 
I have the feeling, that the DEM in litchi is faulty and that this is causing our problems. So I am thinking about importing a different DEM into litchi. Do you know if this works well? And would you know a provider for elevation maps?
 
importing a different DEM into litchi. Do you know if this works well?
Yes, it works well as long the data is in WGS-84 Esri ASCII Grid format.
As already mentioned, the accuracy might not enough for your situation, even commercial providers like Airbus state "Up to 1.5m vertical accuracy at 0.5m grid spacing"

And would you know a provider for elevation maps?
Use Google... there are many, providing free DEMs and of course commercial providers.

But in your case, I would create your own DEM with aircraft equipped with LiDAR sensors or other devices capable creating DEM.
 
Note that there are 2 sources of potential error. Fixing 1 won’t fix the other. DEM s have some errors within them, particularly noticeable when crossing strip boundaries. The drone’s altitude is also a source of errors, as it is a barometrically derived value, and varies based on the atmospheric conditions.

They both contribute by adding errors.
 
Hello all,

The drone maintains altitude relatively well at first, but after about a third of the mission the drone begins to climb to 5-6 m or higher. This happens at different locations with different elevation profiles. Even over very flat areas.


ciao , same problem only when I use mavic 2 pro. I normally use litchi and the same waypoint route both for mavic and phantom 3. ph 3 has no problem to maintain low altitude (8 meter) constant for all the route.

I use drone to monitor the status of my vineyard; a complete lap take 4 minute and with mavic after 1/3 the real altitude change. I have tried to install the new firmware and make imu calib. no way, same problem
 
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