Mavic flight data - need to figure why altitude dropped.

Brojon · Jul 14, 2017

I know I saw somewhere how to tell DJI - or maybe Litchi - to save the flight data on the card so it could be combined with video.
Can someone tell me what switch to flip in teh settings for this and any info on data format?
Appreciate it.

Reason being I sent it out on a new Litchi mission yesterday that I had set the waypoints as 80' relative to ground. It appeared to gradually *lose* altitude as the mission progressed. Towards the end I was maybe 10-20 feet tops over the phone poles which I had measured at 40' in height. I could clearly distinguish the individual wires and count the insulators. I know I wasn't at the full 80' since I got *very* close to a couple of treetops on the way back. Trying to figure out if it really was that low or just my perspective from looking at the video.
The area that I flew in goes down in altitude a bit then gradually back up on the return leg it's almost like it didn't quite make it back up to flying height.

Ed_2020 · Jul 14, 2017

I don't have Litchi open here, but you need to set 'Video Caption' on. It will record a text file along with the video file (*.SRT file).

The file is not a full log, sample of recordings bellow (12 min flight had aroud 25.000 records, Barometer = meters in this example):

2
00:00:00,060 --> 00:00:00,090
HOME(-89.7166,29.3326) 2017.03.22 07:06:59
GPS(-89.7166,29.3326,15) BAROMETER:1.3
ISO:100 Shutter:6400 EV: 0 Fnum:F2.2

3
00:00:00,090 --> 00:00:00,120
HOME(-89.7166,29.3326) 2017.03.22 07:06:59
GPS(-89.7166,29.3326,15) BAROMETER:1.3
ISO:100 Shutter:6400 EV: 0 Fnum:F2.2

My experience with Litchi so far shows great accuracy between planned and recorded heights.

Sudden barometric changes will affect real height.

Brojon · Jul 14, 2017

Interesting - the post that I saw before the guy had used some software to impose the flight data I thought included height on the video.
I guess they must use the barometer somehow to determine height but that is notoriously inaccurate...
Found the video - it apparently uses Dashware and does include height.

This was in teh comments:

Good,
Data was collected from Mavic via the USB Port with the 'DJI Assistant 2' application.
The file in * .DAT format was converted to Excel * .csv with the application 'DatCon.2.4.3'.
All info on the site: DatCon Downloads

Ed_2020 · Jul 14, 2017

Brojon said:
Interesting - the post that I saw before the guy had used some software to impose the flight data I thought included height on the video.
I guess they must use the barometer somehow to determine height but that is notoriously inaccurate...
Found the video - it apparently uses Dashware and does include height.

This was in teh comments:

To view this content we will need your consent to set third party cookies.
For more detailed information, see our cookies page.