Good morning,
(DJI phantom 2vision+ gen3)

I'm having an issue with incorrect altitude on the geotag information from captured images.
The latitude and longitude look as thought they're correct but the altitude (Above sea level) is about ninety feet to low.
This isnt a one shot incident it's every flight.
This greatly affects the accuracy of the projects made in Pix4d.

The actual ground level is 185ft above sea level, I flew the pattern at 30meters (98 feet) above that but the geotag information states it was captured at 194.3

Is there any wat to re-calibrate this parameter or is it strictly from satelite information? Thanks guys.

The Altitude data in the Exif information is calculated from the GPS satellite information and can not be adjusted.
It is worth noting that the vertical (height) accuracy of the GPS is not that good.
The other thing to consider is what you used to measure the ground level ? And that you are then using the Phantom barometer to hold 30mtrs altitude from the home point.
You cant really compare an altimeter (pressure) reading to a GPS (data calculated) reading.

If you use the DJI app you will see that the altitude is always miles off what it actually is, ive had my quad hover in front of me and im 6ft tall, the app said it was 12ft off the ground, you can try letting the quad sit for a minute after startup then power off the quad and then power on the quad, this has proven to reset the altitude correctly occasionally.

That said the Naza unit is really bad at accurately measuring altitude due to its cheaper internal components, and there isn't much you can do about it, short of buying a top of the range unit.

johnwarr@live.c Posted at 2015-7-10 06:03
The Altitude data in the Exif information is calculated from the GPS satellite information and can n ...

Thanks John, and thanks crash
I'm using information from an engineering firm that surveys the area to get the actual "at ground level".

I'm getting more info from other sources that state basically the same as yours... the GPS just isn't that good in the Phantom (not for commercial use anyways) ..