Altitude reading vs photo meta data

[photo2be]

Hi, my Mini2 works just excellent! Today I flew about 35-40m in the air,,... didn't look at the screen but the META data info in the final pic said 142m!
Any clue why?? No "warnings". It was rock steady in the air and landed just perfect.

 

[DanMan32]

EXIF uses AMSL from GPS rather than AGL. Same for video caption.

 

[photo2be]

EXIF uses AMSL from GPS rather than AGL. Same for video caption.

Wow, Thanx Danman! I learn every day from this forum. Strange how much it differs! I was quite close to sea-level.
Max 5-10meters.

 

[Deleted member 103366]

Plus the 'gps' height in the exif is probably not very accurate. I have seen the GPS height reported in the flight logs as 70ft ( I can't remember if that was above or below sea level ) when the drone was maybe 10ft above sea level at the beach.

 

[Meta4]

Strange how much it differs! I was quite close to sea-level.
Max 5-10meters.

There are a couple of factors affecting this.
Although DJI label one of the altitude fields in the metadata GPS Altitude, for most DJI drones, the number does not come from GPS.
Instead it comes from a completely unreliable conversion from air pressure that uses invalid assumptions.

And if the Mini 2 is actually using GPS data, the reason that could be inaccurate is that GPS does not know where sea level really is because it uses a mathematical approximation that does not properly account for the irregular shape of the earth.

Mean Sea Level, GPS, and the Geoid | Summer 2003 | ArcUser

Frequently research and technology endeavors have unforeseen but positive outcomes.

www.esri.com

 

[DanMan32]

Plus the 'gps' height in the exif is probably not very accurate. I have seen the GPS height reported in the flight logs as 70ft ( I can't remember if that was above or below sea level ) when the drone was maybe 10ft above sea level at the beach.

Perhaps you had a 60ft surge? [emoji3]

 

[photo2be]

There are a couple of factors affecting this.
Although DJI label one of the altitude fields in the metadata GPS Altitude, for most DJI drones, the number does not come from GPS.
Instead it comes from a completely unreliable conversion from air pressure that uses invalid assumptions.

And if the Mini 2 is actually using GPS data, the reason that could be inaccurate is that GPS does not know where sea level really is because it uses a mathematical approximation that does not properly account for the irregular shape of the earth.

Mean Sea Level, GPS, and the Geoid | Summer 2003 | ArcUser

Frequently research and technology endeavors have unforeseen but positive outcomes.

www.esri.com

Thanx all for your info! Then I know that the EXIF/META is not to trust!