I notices the negative -3m height while flying this morning? Is that normal? Anything that I need to do? Please advise. TY

This may or may not be the case, but DJI drones record where they take off from as being 0 height. So if you take off from say a picnic table and then land on the ground, there will be negative height. If this isn't the case, you may need to calibrate your sensors and if it still does it, you may have something else going on. I'm not putting the blame on any particular thing, just giving possibilities to look for.

Take off from a hill and fly down it - you'll see a negative altitude as the altitude is based on zero being the home point as JodyB stated.

It looks like the previous two posters didn't pay much attention to your app screenshot.
The altitude comes from a barometric sensor that measures air pressure.
It's common and normal for the air pressure to change a little over the time of a flight and the altitude shown can be +/- a few metres by the end of the flight.
If it's just a little, that's no problem.
But if it's consistently too much, recalibrating your IMU might improve things.

I did pay attention. When I stated that OP may have something else going on, that included the barometric sensor. I also stated that OP may need to calibrate the aircraft's sensors. I tend to look at simple things first. Then move on from there. Sensors are not 100% accurate, but they should be within a certain percentage.

Hello guys, many thanks for your input. I was landing in almost the same place as the take off, maybe 1 or 2 meters away, surely was at the same height, no hills or anything.
I will have some more flights and will see if the error is still there. If so, I will look to the calibration routine again. I have recently calibrated the gimbal, compass and imu after the last update (0340).
Are there any other calibrations possible?
Ty again.

Paultbg Posted at 8-14 10:48
Hello guys, many thanks for your input. I was landing in almost the same place as the take off, maybe 1 or 2 meters away, surely was at the same height, no hills or anything.
I will have some more flights and will see if the error is still there. If so, I will look to the calibration routine again. I have recently calibrated the gimbal, compass and imu after the last update (0340).
Are there any other calibrations possible?

Connect the drone to the latest version of Assistant 2 for Mavic and you can calibrate the downward vision and obstacle avoidance sensors.
If you turn on just the remote and connect it to the phone then enter the app without turning on the drone you can calibrate the remote controller sticks and dial.
Those are the five calibrations.

A J Posted at 8-14 11:13
Connect the drone to the latest version of Assistant 2 for Mavic and you can calibrate the downward vision and obstacle avoidance sensors.
If you turn on just the remote and connect it to the phone then enter the app without turning on the drone you can calibrate the remote controller sticks and dial.
Those are the five calibrations.

TY, I'll have a look.

Paultbg Posted at 8-14 11:23
TY, I'll have a look.

You're welcome

the sensors may not have been an issue I've had it update the home point about 3 minutes after take off, and then show negative altitude from then on.

think it was a lack of GPS connections at the time of take off that then remedied itself once the drone moved to a better spot to register enough satellites.

XbladezDW Posted at 8-14 15:22
the sensors may not have been an issue I've had it update the home point about 3 minutes after take off, and then show negative altitude from then on.

think it was a lack of GPS connections at the time of take off that then remedied itself once the drone moved to a better spot to register enough satellites.

GPS has nothing to do with zero altitude setting.
The altitude is set immediately on powering up and uses a barometric sensor, not GPS.
Your Home point resetting after takeoff has no effect on the zero altitude.

Lab rouses is correct. The drone uses the barometric sensor to determine altitude at start up and not gps. If after calibrations are complete, if it is just a little off, that’s probably normal, but if it’s a lot off, then you may have a wonky barometric sensor. I would just about start a case with DJI and see what they have to allow if that turns out that is still off by a good margin.