Mini 3 Pro GPS AGL variation (accuracy) during flight?

[Al Di]

Today I was flying my Mini 3 Pro around a lake taking movies of boats and scenery. I established my RTH prior to take off. When I was approaching my return location I noticed my AGL indication was -15 feet or so. I had expected to see something around zero. This happened on each of three flights. I never noticed this before since I am concentrating on a visual landing. What is the expected lateral and vertical variations (accuracy) with DJI GPS? Thanks, and be well fellow flyers.

 

[mavic3usa]

Today I was flying my Mini 3 Pro around a lake taking movies of boats and scenery. I established my RTH prior to take off. When I was approaching my return location I noticed my AGL indication was -15 feet or so. I had expected to see something around zero. This happened on each of three flights. I never noticed this before since I am concentrating on a visual landing. What is the expected lateral and vertical variations (accuracy) with DJI GPS? Thanks, and be well fellow flyers.

Sometimes, it's off. I saw it yesterday after 10 feet below. It doesn't happen very often but it's not perfect; you shouldn't see it alot. BTW, it's not an AGL indicator since the drone doesn't know how high above the ground it is hover. The indicator will show you how high above the home point where you took off from. Should reset back to zero when you change the battery and start out again.

 

[Al Di]

Sorry if there was any confusion about AGL. Since I established my RTH position at ground level, I judged it was appropriate to use. However, as you stated, it is the Variation from my established plane of reference at the time the drone created it's RTH position an not necessarily AGL.

 

[Yorkshire_Pud]

Height, as displayed in the App, is measured by a barometer, not GPS.
GPS height may be listed in the log but is from memory woefully inaccurate by 10's of feet and or more.
And yes the barometric height can vary/drift, which is why you shouldn't aim to clear an obstacle during RTH by a few ft, I normally aim to clear it by 10m or so.

 

[Al Di]

Okay, that makes sense. We are in a range of mountains and we have had very unstable weather. Rain, sun, etc. I will pay more attention to my mico environment ... as I should anyways. Just for edification, does anyone know the accuracy of the onboard barometer?

 

[Hauptmann]

Sensors on drones tend to get confused when flying over reflective surfaces such as water. I've had near splashdowns when the drone "thought" it was at a higher altitude.

 

[Meta4]

Sensors on drones tend to get confused when flying over reflective surfaces such as water.

The OP's incident is not related to VPS sensors flying over reflective surfaces.
It's a result of changing air pressure over the duration of the flight.
It's common and normal.

 

[Al Di]

Thank you all for jumping in on this thread. I have learned a lot.
Be well everyone and may your drones always return home.