Spark seems to store completely incorrect data in `GPS Altitude' field in exif. Look at the following two examples: DJI_0027.JPG, DJI_0030.JPG
The second on is obviously take at a lower altitude. Check their exifs.
For the first picture:
>  exiftool DJI_0027.JPG | grep "GPS"
we have:
GPS Version ID                  : 3.2.0.0
GPS Latitude Ref                : North
GPS Longitude Ref               : East
GPS Altitude Ref                : Above Sea Level
GPS Altitude                    : 5.7 m Above Sea Level
GPS Latitude                    : 50 deg 11' 28.00" N
GPS Longitude                   : 18 deg 58' 44.00" E
GPS Position                    : 50 deg 11' 28.00" N, 18 deg 58' 44.00" E
This is clearly rubbish since the ground level at this point is circa 280-290 m above see level. Hence I could not take a picture 5.7 m above see level.

The second picture gives even more surprising results (it shoul give a lower altitude):
> exiftool DJI_0030.JPG | grep "GPS"
GPS Version ID                  : 3.2.0.0
GPS Latitude Ref                : North
GPS Longitude Ref               : East
GPS Altitude Ref                : Above Sea Level
GPS Altitude                    : 6551.3 m Above Sea Level
GPS Latitude                    : 50 deg 11' 28.00" N
GPS Longitude                   : 18 deg 58' 44.00" E
GPS Position                    : 50 deg 11' 28.00" N, 18 deg 58' 44.00" E

The exif says that it was taken 6.5km above sea level!

I would reflect this situation to our engineers. And please tell me the version of your app and provide me your DJI Account. What is the date you shoot this photo?

DJI Elektra Posted at 2017-10-21 00:52
I would reflect this situation to our engineers. And please tell me the version of your app and provide me your DJI Account. What is the date you shoot this photo?

1) The photo was take on 2017/10/16.
2) The firmware is the current one i.e. 01.00.0600.  
3) The app version is 4.1.9 (as I reported earlier 4.1.10 does not work on my phone), but this is anyway probably irrelevant as the wrong exif data is in the jfif file on SD card, which is saved by the drone firmware not by the Android app.
4) The dji account I will send by p/m

_pk Posted at 2017-10-21 02:39
1) The photo was take on 2017/10/16.
2) The firmware is the current one i.e. 01.00.0600.  
3) The app version is 4.1.9 (as I reported earlier 4.1.10 does not work on my phone), but this is anyway probably irrelevant as the wrong exif data is in the jfif file on SD card, which is saved by the drone firmware not by the Android app.

Thanks for your update.

DJI Elektra Posted at 2017-10-21 00:52
I would reflect this situation to our engineers. And please tell me the version of your app and provide me your DJI Account. What is the date you shoot this photo?

Hmmm... It seems that personal messaging does not work (Firefox 52.1.1, 64 bit on OpenSuse Linux 42.1)... Weird.
Is my DJI account relevant, anyway?

OH DEER....sorry could not help the pun ! LOL

wobbles Posted at 2017-10-21 03:07
OH DEER....sorry could not help the pun ! LOL

So? Which part is so funny for you? The fact that the Spark's firmware has a bug? Or the fact that the PMs do not work?
Anyway, thank you for your important contribution to the discussion.

Sorry, Wobbles I misinterpreted you message (I'm not a native English speaker) until I put 'pun' into a translator. But it was to late to correct my too quick response.

_pk Posted at 2017-10-21 03:17
Sorry, Wobbles I misinterpreted you message (I'm not a native English speaker) until I put 'pun' into a translator. But it was to late to correct my too quick response.

lol no worries ..

They are a lot issues with spark... In previous version I had altitude errors also I had fake attitude mode and warnings about no fly zone even the nearest no fly zone is 100km away....The notorious about these false alarms is that they appear for seconds and they are not registered in flight record....

Pk, we need your flight data and black box data for further analysis. Please upload to dropbox and post the link. Thanks for your support.

DJI Elektra Posted at 2017-10-25 19:34
Pk, we need your flight data and black box data for further analysis. Please upload to dropbox and post the link. Thanks for your support.
https://www.youtube.com/watch?v=ngEHdAlAh9A&t=2s

Ok. I will try to provide the data. But how to export them under Linux?

_pk Posted at 2017-10-25 23:40
Ok. I will try to provide the data. But how to export them under Linux?

Please download DJI Assistant 2 through our website. Here is the link:
http://www.dji.com/spark/info#downloads.

DJI Elektra Posted at 2017-10-26 03:24
Please download DJI Assistant 2 through our website. Here is the link:
http://www.dji.com/spark/info#downloads.

There are only Windows and Mac versions there. Windows version does not work under wine on Linux. So I repeat my question: how do I export the data under Linux?

Sorry to hear that you are having issues with altitude calculations with your Spark.  Glad to see DJI is helping and keep us posted on the outcome of the issue.

Sparky_17 Posted at 2017-10-26 04:24
Sorry to hear that you are having issues with altitude calculations with your Spark.  Glad to see DJI is helping and keep us posted on the outcome of the issue.

I don't think there are actual issues with altitude calculation, since Spark (both on that that day and later too) behaved normally. The flight log in my phone shows reasonable values of altitude. My guess is that it is strictly the way Spark saves data in image exif that is wrong. Evidently a bug in the firmware.

BTW, definitely this is not an issue with only my Spark. I have just taken time to browse through some other threads containing photos. While most photos do not have exif data at all, if you check this thread:
https://forum.dji.com/thread-115970-1-5.html
you will notice that the first photo (taken near ground level) reports as 6553.2m altitude, while the second one (take evidently higher) reports as 9m ! Clearly the exif data is incorrect. As said earlier - evidently a bug in the firmware.

_pk Posted at 2017-10-26 05:08
I don't think there are actual issues with altitude calculation, since Spark (both on that that day and later too) behaved normally. The flight log in my phone shows reasonable values of altitude. My guess is that it is strictly the way Spark saves data in image exif that is wrong. Evidently a bug in the firmware.

Thanks for the clarification and information

_pk Posted at 2017-10-26 04:00
There are only Windows and Mac versions there. Windows version does not work under wine on Linux. So I repeat my question: how do I export the data under Linux?

Please change another computer with Windows or Mac system to export the data. There is no Linux version of DJI Assistant 2  Linux version. Thanks for your understanding.