Mavic 2 Pro Altitude

[nd4wmike]

When flying my Mavic 2 Pro in a very large field that for the most part is wide open , I get erroneous altitude readings , The ground is flat and nothing there , but since the spring time is here there is 3-4 foot grass growing .
Any ideas ?
After a few minutes of flying from take off to around 200 ft up and around 1200 ft out , the altitude goes to a negative number like -15 ft .
Thanks
Mike

 

[tcope]

Altitude is based on the take off point. If you are 10' above the take off point, your altitude will read as 10', even if you just flew over a cliff and you are now 200' above the ground underneath. If you fly own a hill you may go under the rake off point and your altitude will be a negative number.

 

[nd4wmike]

Thanks for reply , I understand the altitude from take and flying above or below it. Like I stated in my post the ground is completely flat under my drone .
Mike

 

[Moose1967]

Calibrate your IMU then do a compass calibration then see if it continues.

 

[Meta4]

Calibrate your IMU then do a compass calibration then see if it continues

The compass is for compass issues and the IMU is for IMU issues.
There's no need to mess with both of them as they are completely separate systems.

Altitude issues have nothing to do with the compass and there's no need at all to mess with the compass.
What you're suggesting is like servicing your car's transmission when you have a problem with the airconditioner.

 

[Moose1967]

Everytime I do an IMU calibration my drone automatically wants to to a compass calibration - not sure why.

 

[Meta4]

Everytime I do an IMU calibration my drone automatically wants to to a compass calibration - not sure why.

Without seeing what/where you are doing it, it's impossible to tell ... but it's not normal.
Where are you doing it?
How can you tell that it wants you to calibrate the compass?
Why are you having to calibrate the IMU?

(my main drone is >2.5 years old and has never had anything calibrated or needed anything calibrated)

 

[Moose1967]

I had a real hard landing one day for no reason at all - then right afterwards I noticed the drone would move up and down slightly and left to right a bit with no input - actually noticed it before the hard landing - the manual says to do an IMU calibration - its not something I do all the time. I do move around a lot with my drone so I do compass ones when I travel more than 50 miles - probably no need but being safe helps !!

 

[Meta4]

probably no need but being safe helps !!

Doing unnecessary calibrations doesn't make anything safer.

 

[EricJT]

Altitude is based on the take off point. If you are 10' above the take off point, your altitude will read as 10', even if you just flew over a cliff and you are now 200' above the ground underneath. If you fly own a hill you may go under the rake off point and your altitude will be a negative number.

I do not follow your explanation.....if the controller doesn't show 210' when you move over the edge of the cliff (I. e. is not additive), why would flying over a hill be subtractive? Logically wouldn't the sensor software treat higher or lower consistently?

 

[kadras]

I do not follow your explanation.....if the controller doesn't show 210' when you move over the edge of the cliff (I. e. is not additive), why would flying over a hill be subtractive? Logically wouldn't the sensor software treat higher or lower consistently?

"If you fly own a hill..." Typo, he means fly "down a hill" from the takeoff point. In that case you're below the takeoff point and the height will show as negative.

 

[Mossiback]

Altitude is based on the take off point. If you are 10' above the take off point, your altitude will read as 10', even if you just flew over a cliff and you are now 200' above the ground underneath. If you fly own a hill you may go under the rake off point and your altitude will be a negative number.

I do not follow your explanation.....if the controller doesn't show 210' when you move over the edge of the cliff (I. e. is not additive), why would flying over a hill be subtractive? Logically wouldn't the sensor software treat higher or lower consistently?

Looks like a typo. He meant to say "if you fly down a hill". Since the height (not altitude) is based on the take off point, if you take off and then fly down a hill your height will be indicated by a negative number relative to the take off point.

 

[EricJT]

Looks like a typo. He meant to say "if you fly down a hill". Since the height (not altitude) is based on the take off point, if you take off and then fly down a hill your height will be indicated by a negative number relative to the take off point.

Ah, so if you fly over the edge of the cliff and then start to descend, it will begin to show a negative number?

 

[Thomas B]

Ah, so if you fly over the edge of the cliff and then start to descend, it will begin to show a negative number?

Yes

 

[EricJT]

Yes

Thank you....it is pleasing to learn something new.