DJI Mini3Pro - Altitude

[DmitryGlinka]

Hi folks
My Mini3Pro has latest firmware and I am use with DJI Fly on my RC-N1 controller with android tablet.
On take off, the drone height is calculated, which is measured from home-point with onboard barometric sensor.
This is not true height (altitude), true altitude is measured from height above sea level.

Is there a way I can get true altitude displayed instead of height from home-point?
Better still would be to show both in the display, not just for legal reasons (so that I stay within 400ft) but also so that I can navigate better?

Thanks everbody!

 

[MS Coast]

Hi folks
My Mini3Pro has latest firmware and I am use with DJI Fly on my RC-N1 controller with android tablet.
On take off, the drone height is calculated, which is measured from home-point with onboard barometric sensor.
This is not true height (altitude), true altitude is measured from height above sea level.

Is there a way I can get true altitude displayed instead of height from home-point?
Better still would be to show both in the display, not just for legal reasons (so that I stay within 400ft) but also so that I can navigate better?

Thanks everbody!

In a word, "No."

 

[Yorkshire_Pud]

Another point is ..... of what use would it be to you?
Neither the AMSL nor the height indicated by the App, let's call it "HaTO", are of any legal consequence.

Assuming that you are a hobby pilot then, from a legal standpoint, you are interested solely in whether or not a string, 400ft long, tied to the bottom of the drone, can touch the ground directly beneath the drone, this is commonly referred to as AGL.
Neither AMSL nor HaTO tell you anythong about AGL unless you know either and respectively,
a) the AMSL of the ground beneath the drone, or
b) the height difference between where the drone took off and the ground beneath the drone at that time.

 

[DmitryGlinka]

In a word, "No."

Ok got it. So the drone doesn't use GPS to determine either height or altitude.
Thanks.

 

[Yorkshire_Pud]

Ok got it. So the drone doesn't use GPS to determine either height or altitude.
Thanks.

Correct

 

[DmitryGlinka]

Another point is ..... of what use would it be to you?
Neither the AMSL nor the height indicated by the App, let's call it "HaTO", are of any legal consequence.

Assuming that you are a hobby pilot then, from a legal standpoint, you are interested solely in whether or not a string, 400ft long, tied to the bottom of the drone, can touch the ground directly beneath the drone, this is commonly referred to as AGL.
Neither AMSL nor HaTO tell you anythong about AGL unless you know either and respectively,
a) the AMSL of the ground beneath the drone, or
b) the height difference between where the drone took off and the ground beneath the drone at that time.

I found a useful link to explain these terms: Height above ground level - Wikipedia

I was think that amsl would be useful as I live near the sea and often launch from a high point then fly over sea. But if the drone doesn't use GPS to determine amsl or hagl then I'll just make do with the height relative to launch site hato.
Thanks

 

[old man mavic]

@DJIMini3Pro33180 as nice as the readings such as height speed distance etc, are to have on the screen,in reality they have little bearing on what the drone is actually doing,relative to its surrounding's ,they are at best a generalisation ,of its position at any given moment relative to the terrain it is flying over
and unless the drone is low enough for the downwards facing sensors to be able to work,then due to the changes in air pressure due to height and wind velocity and weather conditions at the time of the flight ,then their accuracy can not be relied upon to much

 

[Hi-Flyer]

Correct

If I understood correctly, the (free) android app named My Elevation gives height above sea level where you are standing - it uses GPS to locate you.

 

[Kilrah]

So the drone doesn't use GPS to determine either height or altitude.

It does use GPS to record altitude, it's just not displayed to you because it's usually not relevant.
You can find it in logs, photo EXIF etc later if needed.

 

[Meta4]

It does use GPS to record altitude, it's just not displayed to you because it's usually not relevant.
You can find it in logs, photo EXIF etc later if needed.

Although it's labelled GPS altitude, it probably doesn't come from GPS.
Whatever its origin, it's highly variable and not useful for anything.

 

[Kilrah]

Although it's labelled GPS altitude, it probably doesn't come from GPS.

Error is quite high there but not that much out of the ordinary, people usually don't realize that GPS is way less precise vertically than horizontally, while the difference between 2 points over a short period of time is usually not that bad on the absolute value +/-50m is normal.
Another reason for not displaying it to the user.

 

[DmitryGlinka]

If I understood correctly, the (free) android app named My Elevation gives height above sea level where you are standing - it uses GPS to locate you.

Thanks. I'll install that app and see how I go. When I add my current elevation to the drone HATO I should in theory know the height above sea level. Also assuming room for error based on what others have said.

 

[Yorkshire_Pud]

Thanks. I'll install that app and see how I go. When I add my current elevation to the drone HATO I should in theory know the height above sea level. Also assuming room for error based on what others have said.

And of what use is that going to be to you during a flight? I am not being awkward
It tells you more concerning AGL which is what you need to be concerned about from a legal point of view than does HATO.
I too have seen ridiculous heights which can only have been derived from GPS. I was literally stood less than 10 ft above sea level and saw a reported height of 70 something, can't remember if it was ± nor if it was ft or m but it was daft.

 

[Meta4]

I too have seen ridiculous heights which can only have been derived from GPS.

It's more likely to be derived from air pressure using an algorithm which assumes standard atmospheric pressure and doesn't allow for normal daily changes in air pressure.

 

[NOLADG]

It's more likely to be derived from air pressure using an algorithm which assumes standard atmospheric pressure and doesn't allow for normal daily changes in air pressure.

I personally think it checks the pressure at startup and then compares how it varies. As once I was flying as a cold front was coming in and my drone was dropping in altitude unexplainably.

 

[Meta4]

I personally think it checks the pressure at startup and then compares how it varies. As once I was flying as a cold front was coming in and my drone was dropping in altitude unexplainably.

It's well known that the height you see on your screen comes from a barometric sensor.
But the last few posts were discussing one of the two different heights showing in the image metadata.
One (Relative Altitude) is the one from your screen.
The other is labelled GPS altitude, but probably doesn't actually come from GPS .. see the image in post #10.

 

[BirdMania]

I broke my old Mini 1 thx to this "height from home point" altitude showing.
I was flying in hillside, making checkup on 20kV air grid pylons, didn't had direct visual contact on my drone, was flying on reading on controller. It shoved me drone is 25meter high, so I turned on left, and in a second hit directly the 20kV steel air wire. :-( (actually on 12m) . Drone fallen crashed to pieces. Gimball broke off,etc.
Later I realized that it not shows me altitude from actual ground surface under, but from home point.
Was an expensive lesson.
So take care on it

 

[ganorthrop]

I just crashed my M3P last weekend, after miscalculating AGL height as I went from sea level, up a slope, only to have my “Height” be around 50’ instead of my original flying height of 125”. I‘ll spare you the details (I recovered my drown with Zero damage beyond various propellers…..otherwise not a scratch!) but included my video right prior to the crash. March 21, 2023 by Glenn Northrop.

 

[MS Coast]

I just crashed my M3P last weekend, after miscalculating AGL height as I went from sea level, up a slope, only to have my “Height” be around 50’ instead of my original flying height of 125”. I‘ll spare you the details (I recovered my drown with Zero damage beyond various propellers…..otherwise not a scratch!) but included my video right prior to the crash. March 21, 2023 by Glenn Northrop.

In the aviation world, that's known as CFIT - controlled flight into terrain.