Wrong GPS altitude on EXIF data

EXIF data on pictures from mission is wrong.
Drone is a DJI Mini 3.
Android app build 1.7.3e

Example of a EXIF from a image using Maps Made Easy app:

Example of a EXIF from a image using standard DJI app:

This second picture was taken close to previous one at a lower altitude.
However, altitude is more accurate as "sea level reference" that one from mission.

David Félix February 18, 2024 23:24

Official comment

Those numbers are the GPS derived altitude numbers. They are notoriously noisy and can vary hundreds of meters between GPS fixes. They are minimally useful in absolute terms. Map Pilot Pro can’t do anything to change the accuracy of those numbers or change how the tags get written. That is handled internally to the DJI camera. This all is the reason we collect the ground reference image at takeoff and then adjust the tags accordingly with relation to the takeoff altitude in Maps Made Easy’s processing. This provides a much more accurate and stable elevation result in the outputs.

Zane February 18, 2024 23:30

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3 comments

Thank you for your answer.

I understand that GPS derived altitude are far from precise.
But please, they can vary to dozens.. not hundreds! :)

All 210 images from this same mission show heights between 3 to 4 meters with "sea level" reference.
This makes no sense. Specially because after mission ended, drone returned to home position without any issue.

Same exact missions a few months ago showed heights between 140 and 90 meters, as expected for this slope.

The only difference besides DJI updates was Map Pilot Pro being upgraded to build 1.7.3e

Right after this last mission I took some pictures with standard DJI app, and heights are more realistic.

OK.. something could happen internally on DJI camera.
Hopefully, in the next few days I'm able to run the mission and compare exif data.

David Félix February 19, 2024 01:36 0 votes

Wow. It’s almost like there was a few hundred meters difference! We have seen some really huge variations between subsequent flights. The amount of time you wait to let the GPS fix settle has a lot to do with it.

The only place the GPS derived altitude really gets used is in the image tags. All flight and navigation is done using relative barometric pressure measurements which is why the flight was fine. You can see those values in what gets recorded in the log file. Flight starts and ends at 0 meters relative.

Zane February 19, 2024 02:05 0 votes