DJI Mavic, Air and Mini Drones
Friendly, Helpful & Knowledgeable Community
Join Us Now

Ground to Altitude in Realtime

JohnLietzke

Well-Known Member
Joined
Jul 21, 2020
Messages
141
Reactions
119
Age
44
Location
Bay Area, California
Would anyone else find it useful to have Realtime Ground to Altitude data while flying?

Most of my flights take place in the hill or mountains. It is hard to gauge your altitude relevant to the ground when flying in mixed terrain. Especially when flying over a valley, down into a valley from an elevated location or up a hill or mountain.

It is surprising that DJI does not include such a feature as elevation is included in almost all raw GPS data derived from mapping. It is understood that this would not applicable without a cellular signal or caching the map before flying.

With this information pilots would have better accuracy and could increase compliance with the FAA ground altitude regulations for unmanned aircraft.

At this point, all I can do postflight is use the equation (takeoff location elevation + altitude) - the elevation from GPS coordinates. I have used Here Technologies to plot my above ground altitude to better refine my visual flying above the ground. Plotting every 5 seconds gives me a much better perspective of height above the ground when I fly in the same area again.

I wrote a scrapper for the downloaded flight data GPS coordinates and altitude using the Home Point as the base elevation then compare that GPS elevation. Then I return this as a nested JSON array [[time, coordinates and hight]] and import it to Here Maps with a sequential line based on time and tags for the altitude.

The only good thing so far using this method is I have never had a negative or zero ground altitude during a flight.
 
Would anyone else find it useful to have Realtime Ground to Altitude data while flying?

Most of my flights take place in the hill or mountains. It is hard to gauge your altitude relevant to the ground when flying in mixed terrain. Especially when flying over a valley, down into a valley from an elevated location or up a hill or mountain.

It is surprising that DJI does not include such a feature as elevation is included in almost all raw GPS data derived from mapping. It is understood that this would not applicable without a cellular signal or caching the map before flying.

With this information pilots would have better accuracy and could increase compliance with the FAA ground altitude regulations for unmanned aircraft.

At this point, all I can do postflight is use the equation (takeoff location elevation + altitude) - the elevation from GPS coordinates. I have used Here Technologies to plot my above ground altitude to better refine my visual flying above the ground. Plotting every 5 seconds gives me a much better perspective of height above the ground when I fly in the same area again.

I wrote a scrapper for the downloaded flight data GPS coordinates and altitude using the Home Point as the base elevation then compare that GPS elevation. Then I return this as a nested JSON array [[time, coordinates and hight]] and import it to Here Maps with a sequential line based on time and tags for the altitude.

The only good thing so far using this method is I have never had a negative or zero ground altitude during a flight.

yes i agree it would be very helpful. i also fly in the mountains so it can be a little tricky sometimes
 
  • Like
Reactions: Howard70
Used a RADALT flying helicopters, very handy especially on IFR approaches.
Would love a radar altitude information on my mini.
 
  • Like
Reactions: Cymruflyer
Would anyone else find it useful to have Realtime Ground to Altitude data while flying?
It would be nice, and should be able to be done with a radar sensor. I looked at this a while ago
Screenshot 2020-10-29 113933.jpg
Still to big and bulky and only good to 60 meters but if it could dummy it down would be nice to incorporate with the drone. Even what you are talking about, having an onboard processor to look at a loaded elevation map and compare to takeoff elevation and gps coordinates to determine current AGL would be great. Just send out the result with the current telemetry. Just seems to easy to do on the internet:)
 
Litchi calculate this automatically if you select altitude base in ground level. Other wise will use altitude base in the takeoff location (not recommended) for the missions.
 
  • Like
Reactions: Otisangb
Litchi calculate this automatically if you select altitude base in ground level. Other wise will use altitude base in the takeoff location (not recommended) for the missions.
I am going to have to check litchi out. I have seen a lot of posts about it but never looked into it. Been to scared to load anything on the sc. That will be cool if I can see actual agl while flying. Thanks
 
I am going to have to check litchi out. I have seen a lot of posts about it but never looked into it. Been to scared to load anything on the sc. That will be cool if I can see actual agl while flying. Thanks
Well, you will not actually see it but the drone will keep the altitude base in ground level. If your set 200FT from ground level and you go to a 50FT hill you will see the altitude raising from 200 to 250FT from the take off altitude but will be 200FT ground level from top of the hill.
 
Well, you will not actually see it but the drone will keep the altitude base in ground level. If your set 200FT from ground level and you go to a 50FT hill you will see the altitude raising from 200 to 250FT from the take off altitude but will be 200FT ground level from top of the hill. Litchi calculate the altitude base in the ground level on google maps information. Of course there is a margen of error always.
 
  • Like
Reactions: Otisangb
I think it is a feature that should be included in the DJI Fly and Go 4 apps. Litchi use the same method I am post-flight in realtime but it is a third party app and there voids you warrantee and also if you had DJI Refresh.

Certainly there is a margin of error and a pilot has to factor that in and be aware of the surrounding and keep VLOS.

The crux of the situation applies to flying over changing terrain where spacial references to elevation are difficult to ascertain. Flying over a valley I am often required by FAA ground altitude to regulations to drop down I usually have preplanned my flight area and have done digital recon of the areas elevation to try to be in compliance when passing over such an area. I am not trying avoid preplanning and elevation gathering prior to flying. It is more about how easy and helpful this feature would be were it included in the DJI fly app.
 
Would anyone else find it useful to have Realtime Ground to Altitude data while flying?

It is surprising that DJI does not include such a feature as elevation is included in almost all raw GPS data derived from mapping. It is understood that this would not applicable without a cellular signal or caching the map before flying.
GPS altitude is only going to give ASL, not height above the ground below your drone.
It's not particularly surprising that DJI don't include such a feature since the only sensors that could give this information are too big and expensive.
It's really not a big deal to estimate your height above the ground, particularly when you already have an accurate indication of how far above or below your launch point the drone is.
The pilots of mast small real planes manage to estimate their height AGL too.
 
  • Like
Reactions: Thomas B
GPS altitude is only going to give ASL, not height above the ground below your drone.
It's not particularly surprising that DJI don't include such a feature since the only sensors that could give this information are too big and expensive.
It's really not a big deal to estimate your height above the ground, particularly when you already have an accurate indication of how far above or below your launch point the drone is.
The pilots of mast small real planes manage to estimate their height AGL too.
When flying real aircraft, you judge your AGL by looking at the size of trees and houses. You get used to those sizes over time and can fairly accurately predict your altitude. You should practice that from different altitudes, say 250ft 500ft 750ft and 1,000ft. Eventually it sinks in, like estimating distances on the ground.

If you practice that from looking at trees straight down from your drone's camera view, you will eventually get a good idea of your height above ground just from the view, so no need to use an instrument, if you just want a rough idea. Though, it would be a nice function and feature to have on a drone.
 
GPS altitude is only going to give ASL, not height above the ground below your drone.
It's not particularly surprising that DJI don't include such a feature since the only sensors that could give this information are too big and expensive.
It's really not a big deal to estimate your height above the ground, particularly when you already have an accurate indication of how far above or below your launch point the drone is.
The pilots of mast small real planes manage to estimate their height AGL too.
What is ASL, I'm not familiar with that term?
 
What is ASL, I'm not familiar with that term?

Above (Mean) Sea Level. Sea height varies around the planet due in part by the tidal forces created by the moon. The ‘mean’ gives an average level as a global reference.
 
Ahh, I've only ever know MSL, not heard of ASL. Thanks

American Sign Language was the only thing that came to mind for ASL.
 
  • Like
Reactions: Camino Ken
...but it is a third party app and there voids you warrantee and also if you had DJI Refresh.

I can’t say for certain with Litchi, but for Dronelink (another third party app), this is what it says in their FAQs:

 
I can’t say for certain with Litchi, but for Dronelink (another third party app), this is what it says in their FAQs:

DJI must be being kind to users as their Warrantee terms exclude coverage for all third part apps. That is good to know.

Thanks
 
but it is a third party app and there voids you warrantee and also if you had DJI Refresh.
The use of a 3rd party app doesn't void anything.
But ...
1. If the 3rd party app can be shown to have caused the problem (unlikely), DJI won't cover you
2. DJI won't accept 3rd party flight data, so if you had used 3rd party software and cannot retrieve the wreckage you're out of luck.
 
  • Like
Reactions: maelstrom

DJI Drone Deals

New Threads

Forum statistics

Threads
130,593
Messages
1,554,205
Members
159,598
Latest member
fast54