Altitude information on the DJI Fly application?

[TeroFin]

Hi!

I am new to drones and just bought my very first drone (Mini). I have flown it now about for two hours and it surprisingly is still intact ?

I have lots of things to learn for sure before I will feel confident with this little creature, but now the biggest issue seems to be that I am not confident with the altitude information I can see on the bottom of the screen (DJI Fly). I first thought it showed the distance from the drone to the groud, but it is now obvious this is not the case. If I am standing up on some hill/slope and send to drone to air it shows about 2 meters ( 6 feet) altitude and this is OK, but if I then fly the drone down the hill, but still keeping the flying level, I would expect the height information to increase, but it seems to go negative. It is like the launching altitude would be some kind of "zero altitude" and if I fly below that, it shows negative numbers. I have done all the calibrations there are available on the SW and the FW of the drone is also the latest one. Should the altitude measurement really work like this? ?

I have read that there are two methods in this drone to define the flying altitude, the barometer and the Visual Positioning System (VPS), but so far I haven't understood which one of these shows the altitude information (or is it some kind of a combo?) and why it is not showing the distance that really would be helpful for the pilot, i.e. ground <--> drone.

Any assistance here would be very appreciated, thanks!

 

[THE CYBORG]

Hi TeroFin welcome to Mavic Pilots.
The altitude is relative to the take off point.

 

[Deleted member 103366]

That is the height 'above' the take of point but as you have found out it goes negative if you drop below the take off point. As you saw negative height you must have descended as you flew away.
Remember it is fairly accurate but not absolutely accurate so.... if you flew off, say, the top of a wall and then dropped to some negative height do not then climb to +6 inches and think that you are guaranteed to clear the wall.
Also if you land, stop & restart the motors and resume flying you are likely to havereset the home point to the landing site. The latter seriously caught me unawares with a Phantom 3 and would have sent the drone for a swim if I hadn't realised why it was asking if I wanted it to land as soon as I triggered an RTH

 

[mano]

Hi!

I am new to drones and just bought my very first drone (Mini). I have flown it now about for two hours and it surprisingly is still intact ?

I have lots of things to learn for sure before I will feel confident with this little creature, but now the biggest issue seems to be that I am not confident with the altitude information I can see on the bottom of the screen (DJI Fly). I first thought it showed the distance from the drone to the groud, but it is now obvious this is not the case. If I am standing up on some hill/slope and send to drone to air it shows about 2 meters ( 6 feet) altitude and this is OK, but if I then fly the drone down the hill, but still keeping the flying level, I would expect the height information to increase, but it seems to go negative. It is like the launching altitude would be some kind of "zero altitude" and if I fly below that, it shows negative numbers. I have done all the calibrations there are available on the SW and the FW of the drone is also the latest one. Should the altitude measurement really work like this? ?

I have read that there are two methods in this drone to define the flying altitude, the barometer and the Visual Positioning System (VPS), but so far I haven't understood which one of these shows the altitude information (or is it some kind of a combo?) and why it is not showing the distance that really would be helpful for the pilot, i.e. ground <--> drone.

Any assistance here would be very appreciated, thanks!

Edit...I just noticed I'm in the wrong section...Mine is a mavic pro, not mini....

I'm having this same issue with my MP and never noticed it on my Spark before....Maybe just because the range is so much further on the MP.

It would seem the altitude display should show an accurate distance between the drone and the ground at all times, otherwise when you are flying in hilly terrain it's extremely dangerous, especially if you want to maintain say, 100' altitude. I damned near flew into some trees because the grade gradually increased, so the drone was telling me I'm at 100' and actually I'm only 20' of the ground.

Is there any way to change this? This is normal you say??????

I have to say, I really enjoy flying my Spark much more, even with it's limitations. It seems so much better designed, way more responsive, and the batteries are much more durable in the Sparks...I have 3 brand new bricked MP batteries that came with my fly more package to prove it, and zero help from DJI.

 

[Deleted member 103366]

Mano, how would you propose that the drone know its ground clearance?
That I know terrain maps and mapping do not take into account trees so that leaves measuring it with sensors. Do you want to pay for sensors that can do that for heights up to, what 500m perhaps?
Where does the pilot's judgement enter into your view of how we should fly?
Sorry but if you were unaware that the indicated height is the height above the take off point and not ground clearance should you be making such flights in the first place?

 

[mano]

Well, I assumed the sensors it has on the bottom measured the altitude, . Obviously something measures the altitude at the home point, so it's not that far a stretch that it would always be monitoring the altitude.

And of course, the owners manual explains all this....yeah sure!!

What good is it to show your home altitude when you are 500' away, I ask?? Just what purpose does that solve? None. The pilots judgement would be a hellova lot better with an accurate idea of how high they are flying. Ummmm, like in a real plane. Or do airplanes guess there altitude all the time when away from their home point. LOL !

I'm sure there are a lot of people who are way more green than me flying these things!! I actually have well over a hundred flights on my Spark, and never encountered the problem on the Spark, so I was really confused. As I stated, maybe the Spoark just didn't get far enough away for the topography to change that much to effect me.

But thanks for the snide reply. Maybe you shouldn't be posting in help forums with your attitude! Obviously I'm not the first to have this question!!

 

[Deleted member 103366]

You are by no means the first to encounter this and you will not be the last but not every many of those people rant about it.
We all make mistakes, including Homer worthy ones, and I think it is better to hold your hands up and say guilty.
In truth I think its pretty clear, from the manual if nothing else, what the indicated height is in relation too.
Page 47 section 19 of the manual.
" 19. Flight Telemetry
D 30M : Distance between the aircraft and the Home Point.
H 10.0M : Height from the Home Point.
HS 10.0M/S : Aircraft horizontal speed.
VS 2.0M/S : Aircraft vertical speed. "

Yes, something does measure height but only when in close proximity to the ground, the " Downward Vision System " as described or mentioned on pages 25, 26 & 38 of the manual.
p26 " The Downward Vision System is only effective when the aircraft is at altitudes of 0.3 to 13 meters."
13m is better than the Mavic 2 Pro's VPS height display limit of somewhere around 10m.
As to what exists in manned aircraft I am clueless but I wouldnt mind betting those systems cost a lot more than the entire MP.

 

[Thomas B]

Hi!

I am new to drones and just bought my very first drone (Mini). I have flown it now about for two hours and it surprisingly is still intact ?

I have lots of things to learn for sure before I will feel confident with this little creature, but now the biggest issue seems to be that I am not confident with the altitude information I can see on the bottom of the screen (DJI Fly). I first thought it showed the distance from the drone to the groud, but it is now obvious this is not the case. If I am standing up on some hill/slope and send to drone to air it shows about 2 meters ( 6 feet) altitude and this is OK, but if I then fly the drone down the hill, but still keeping the flying level, I would expect the height information to increase, but it seems to go negative. It is like the launching altitude would be some kind of "zero altitude" and if I fly below that, it shows negative numbers. I have done all the calibrations there are available on the SW and the FW of the drone is also the latest one. Should the altitude measurement really work like this? ?

I have read that there are two methods in this drone to define the flying altitude, the barometer and the Visual Positioning System (VPS), but so far I haven't understood which one of these shows the altitude information (or is it some kind of a combo?) and why it is not showing the distance that really would be helpful for the pilot, i.e. ground <--> drone.

Any assistance here would be very appreciated, thanks!

This is exactly how it functions. TO point is always registerred as zero altitude and relative altitudes displayed.

 

[Meta4]

What good is it to show your home altitude when you are 500' away, I ask?? Just what purpose does that solve? None. The pilots judgement would be a hellova lot better with an accurate idea of how high they are flying.
Ummmm, like in a real plane. Or do airplanes guess there altitude all the time when away from their home point. LOL !

You might be surprised to find out that is exactly how the pilots of most small aircraft work, because radar altimeters are quite expensive.
Except they calibrate their altimeters to show height above sea level.
Estimating your height above the ground isn't an insurmountable problem, particularly when you already have tour height above the launch point to work from.

 

[TeroFin]

This is a good video to shed some light to this topic. AGL function would be what I was looking for when I still didn't know anything about drones (still don't too much....)

To view this content we will need your consent to set third party cookies.
For more detailed information, see our cookies page.

Accept third party cookies

In the DroneLink SW there are two options for the reference point:

- TakeOff Location (this is what DJI FLY uses)
- AboveGroundLevel (AGL)