Some mapping test notes

grythumn · Apr 3, 2022

I've been trying a few mapping test runs with my Mini 1, and thought I'd jot down some notes:

1) Don't fly in Imperial units. Exif tags recorded the absolute altitude in feet or something, and the relative altitude in meters. ArcGIS Pro really didn't like this; I tried all the settings I could to override, but it failed to adjust the images.
Same site, takeoff point within a few meters:
Run1: Absolute Altitude : +197.41 , Relative Altitude : +53.00
Run2: Absolute Altitude : +64.30 , Relative Altitude : +49.90
2) Fastest Litchi could snap images was about a second. Drone Harmony defaults to 2s; probably more reliable.
3) Drone Harmony is the only mapping application I've gotten to work with the Mini thus far (didn't get Pix4D or DroneDeploy working).
4) OpenDroneMap is pretty easy to use out of the box. I'm having trouble with the automated surface mapping on buildings even with high side/overlap; still playing with settings. ArcGIS Pro is still processing; haven't seen what kind of output it produces yet.
5) The Mini is easy to lose visually; I need to get a strobe or something.
6) Pictures are cropped to 16:9 unless you change the aspect ratio in DJI fly first.
7) The controller loses power fast with my android phone. It was at 2 dots after the 3rd flight battery.

Anyone else mapping with the Mini? Any tips?

Recoveryone · Apr 3, 2022

Meta4 · Apr 3, 2022

grythumn said:
1) Don't fly in Imperial units. Exif tags recorded the absolute altitude in feet or something, and the relative altitude in meters. ArcGIS Pro really didn't like this; I tried all the settings I could to override, but it failed to adjust the images.

The camera will record the absolute and relative altitudes both in metres.
That can't be changed.

grythumn · Apr 4, 2022

Meta4 said:
The camera will record the absolute and relative altitudes both in metres.
That can't be changed.

The absolute altitude of my test site had a difference of about 130 units between the two flights, according to the EXIF data. I could be wrong about the cause; the first flight was in Litchi, second, third and fourth were flown from Drone Harmony, or it could be something else entirely. I can try another short flight in imperial and see if I can reproduce it.

Arcmap Pro has been crashing trying to generate a DSM and DTM from the 50m flight (the ever fun error 99999). I was able to generate an ortho from a generic 2M DEM, but as expected it mangled the building without a high resolution DTM. I'll try it on another machine and see if I can reproduce it, and see if it likes the 75m flight data better.

grythumn · Apr 4, 2022

Recoveryone said:
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I couldn't get DroneDeploy to work on my Mini; it was an option in the program, but when I went to start a flight it kept complaining about the flight mode, whether I was starting it on the ground or already in the air. Trial's expired at this point, so I can't mess with it any more.

Meta4 · Apr 5, 2022

grythumn said:
The absolute altitude of my test site had a difference of about 130 units between the two flights, according to the EXIF data. I could be wrong about the cause; the first flight was in Litchi, second, third and fourth were flown from Drone Harmony, or it could be something else entirely. I can try another short flight in imperial and see if I can reproduce it.

The exif data is in metric and the absolute altitude could be out by a long way because of the odd way that DJI calculates it.
It doesn't matter which app you fly with, it's the drone's firmware that dictates the format of the metadata.

Recoveryone · Apr 5, 2022

grythumn said:
I couldn't get DroneDeploy to work on my Mini; it was an option in the program, but when I went to start a flight it kept complaining about the flight mode, whether I was starting it on the ground or already in the air. Trial's expired at this point, so I can't mess with it any more.

The software is free to download, the free trial is for the processing of the photos. You can still use it to fly and create mapping locations. You can use other software to process the stiching your photos together. You must start the flight on the ground with the props off or it will not load the mission properly.