EXIF altitude data comes from where?

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Does the EXIF data read the GPS or barometer with regards to altitude?

My image EXIF file shows 19.1 meters (62.7 feet) but Google Earth shows it 371 feet or a difference of about 300 feet!?

Another photo shows EXIF of 682.2 meters (2,238.2 feet), but Google Earth shows it as 2,437 feet or 200 feet difference?

If the GPS is less accurate and the barometer, I'm guessing the EXIF altitude is from the GPS data. Correct?

I was planning on using the photo's EXIF altitude for setting waypoint heights, but due to the large differences I don't think it would be wise to go from the image's altitude reading to setting it on a waypoint for a mission.

Fwiw, the EXIF on the GPS latitude and longitude was spot on in Google Earth.
 
Does the EXIF data read the GPS or barometer with regards to altitude?
GPS altitude data is woefully inaccurate and commonly +/- 200 feet or more out and swinging over short time periods.
Your Phantom uses the barometer for all flight purposes but for some unexplained reason a year ago DJI changed the source of exif altitude info from barometer to GPS.
It's of no use to anyone and a total mystery why they did it.
 
GPS altitude data is woefully inaccurate and commonly +/- 200 feet or more out and swinging over short time periods.
Your Phantom uses the barometer for all flight purposes but for some unexplained reason a year ago DJI changed the source of exif altitude info from barometer to GPS.
It's of no use to anyone and a total mystery why they did it.

Thanks.

Guess I won't try and use the EXIF altitude data for future flight planning. I was hoping to use it for waypoints for pre-flights. Thought I could do strafing runs at 10 feet knowing the EXIF altitudes beforehand. Oh well....
 
GPS altitude data is woefully inaccurate and commonly +/- 200 feet or more out and swinging over short time periods.
Your Phantom uses the barometer for all flight purposes but for some unexplained reason a year ago DJI changed the source of exif altitude info from barometer to GPS.
It's of no use to anyone and a total mystery why they did it.
That is a pity. The barometer data (height in m) is stored together with ISO, Shutter and EV in the video meta data file(.SRT).

Maybe we can ask someone from DJI on the DJI Phantom forum? to explain why they changed from barometer height (correct) to GPS (inaccurate) and if it is possible to change this (again) and add all the other SRT data also in the exif data in a next FW release.
 
Maybe we can ask someone from DJI on the DJI Phantom forum? to explain why they changed from barometer height (correct) to GPS (inaccurate) and if it is possible to change this (again) and add all the other SRT data also in the exif data in a next FW release.
The DJI people on their forum have no idea why it was changed and haven't responded to any suggestions of changing it.
 
Presumably the problem with using the barometer is that those data are uncalibrated for absolute altitude. So fine for altitude relative to takeoff point, but no good for MSL altitude.

GPS altitude may be a bit less accurate (although with a good lock it should be reasonable) but at least it is not highly dependent on the local atmospheric conditions.
 
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Presumably the problem with using the barometer is that those data are uncalibrated for absolute altitude. So fine for altitude relative to takeoff point, but no good for MSL altitude.

GPS altitude may be a bit less accurate (although with a good lock it should be reasonable) but at least it is not highly dependent on the local atmospheric conditions.
That is why I want DJI to store all data (GPS and Barometer) in the exif file. That should be easy for them.
 
Barometric altitude varies with weather related barometric changes. Over the duration of a typical drone flight, the local pressure would not vary enough to effect the altitude reading from the onboard pressure sensor, but changes over hours or a day or so can change your indicated barometric altitude several hundred feet up or down. Pilots would always zero their Altimeter to 0 feet AGL just prior to takeoff just because of this.
 

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