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Possible add-on on DJI FlyApp: GPS Elevation
346 10 4-18 00:14
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Raf_IZ0QWM
Second Officer
Flight distance : 262523 ft
Italy
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Hi all,
I know that GPS altitude is correct around 10-15m if there are many satellites but ublox provides enough information to know when to show it.

Why not also show the GPS altitude as well as that of the barometer and therefore the difference from the place of takeoff?


Thank you
4-18 00:14
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DAFlys
Captain
Flight distance : 1346821 ft
United Kingdom
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Possibly to avoid confusion about the rules,   for example the 400ft rule is AGL not ASL and this would surely be confusing to many.
4-18 01:14
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JJB*
Captain
Flight distance : 6621798 ft
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Netherlands
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well, i prefer to see VPS height !  really important to see when flying low.  
4-18 01:26
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Raf_IZ0QWM
Second Officer
Flight distance : 262523 ft
Italy
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You're right but I don't want to exclude anything. Just adding the value.
Usually I'm on top of a mountain and I fly down so I see negative values, yes I'm going down but it could be useful to know the GPS altitude (with a smaller font) just to not create confusion.

4-18 01:44
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DJI Stephen
Super Moderator

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Hello there Raf_IZ0QWM. Good day and thank you for sharing your valued insights with regards to this matter here at DJI Forum. I will forward these information and this thread to the designated DJI department for further attention. All significant suggestions or requests will be implemented after the evaluation of the DJI Engineers. For the latest DJI updates please stay tuned to our DJI official website at www.dji.com. Thank you.
4-18 18:39
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Raf_IZ0QWM
Second Officer
Flight distance : 262523 ft
Italy
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Speaking of altitude, I'm seeing a lot of altitude issues around, probably introduced in the last release.
Some users are increasingly seeing negative altitude after take off, and even, if the drone takes off and then lands, the altitude has changed and does not return to 0.

Some other problem is the inability to perform MasterShots with the DJI Air2s due to areas where the limit of 0m cannot be exceeded that never existed with the Mavic Air2 (and still do not exist).

I would not like that some bugs have been introduced on DJI Fly's 1.4.0.
4-22 06:55
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Northwood
Captain
Flight distance : 978934 ft
Canada
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I like the suggestion.  I fly in areas where there are significant changes in elevation also.  Being able to see relative to home point as well as actual altitude (even approximately) would be beneficial.
4-22 13:08
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Geebax
Captain
Australia
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Raf_IZ0QWM Posted at 4-22 06:55
Speaking of altitude, I'm seeing a lot of altitude issues around, probably introduced in the last release.
Some users are increasingly seeing negative altitude after take off, and even, if the drone takes off and then lands, the altitude has changed and does not return to 0.

All measurement systems have a degree of inaccuracy, and measurement of altitude is difficult to any degree of precision. The basic method is a barometer, the same technology as used by full size aircraft. DJI add to that with VPS or downwards sensors to measure altitude, but VPS is only good to about 30 Meters in altitude before it cuts out. GPS,  on the other hand, is woefully inaccurate at any time, and that is why DJI do not use it. This from Wiki:

"Global Positioning System (GPS) receivers can also determine altitude by trilateration with four or more satellites. ... In hiking and climbing, it is common to find that the altitude measured by GPS is off by as much as 400 feet (122 metres) depending on satellite orientation."
4-22 14:46
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TPM_
lvl.2
Mexico
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I need that gps elevation too because on photogrammetry i have negative values on my 3D model, i cant even use ground control points because im 500 metres  above sea lvl and the images have the fly height (50 metres) .
4-22 19:54
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Raf_IZ0QWM
Second Officer
Flight distance : 262523 ft
Italy
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Geebax Posted at 4-22 14:46
All measurement systems have a degree of inaccuracy, and measurement of altitude is difficult to any degree of precision. The basic method is a barometer, the same technology as used by full size aircraft. DJI add to that with VPS or downwards sensors to measure altitude, but VPS is only good to about 30 Meters in altitude before it cuts out. GPS,  on the other hand, is woefully inaccurate at any time, and that is why DJI do not use it. This from Wiki:

"Global Positioning System (GPS) receivers can also determine altitude by trilateration with four or more satellites. ... In hiking and climbing, it is common to find that the altitude measured by GPS is off by as much as 400 feet (122 metres) depending on satellite orientation."

Yes but first, I'm not saying to use it for the aircraft's navigation system and second, ublox, which is the chip used by DJI, has a good system inside to give the elevation correct enough when in 3D fix mode .
There are datasheets and some manuals written by ublox.
4-22 20:01
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Geebax
Captain
Australia
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Raf_IZ0QWM Posted at 4-22 20:01
Yes but first, I'm not saying to use it for the aircraft's navigation system and second, ublox, which is the chip used by DJI, has a good system inside to give the elevation correct enough when in 3D fix mode .
There are datasheets and some manuals written by ublox.

If DJI were to display the GPS altitude, within a millisecond there would be a hundred people on this forum complaining that the altitude is incorrect. Better to ignore it and provide a value from a system that is inherently more accurate. It does not matter what ublox provide, the GPS system is basically flawed and will not ever provide a reasonably accurate reading of altitude. Do yourself a favor and Google 'GPS height accuracy'. BTW, if you call up the metadata of each photo, the GPS altitude is actually written into it, it's just no-one who knows anything about the GPS system will actually use it for obvious reasons.
4-22 21:47
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