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Auto height above ground level?

stevebarnes

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I tried flying my M3 Classic behind the car recently as I went up into the hills where I live so my daughter could share the drive with a friend. It's REALLY difficult to track at a consistent height above ground level! I have concluded a mount on the bonnet may be a good idea, but that means the bumps would affect the gimbal's height, despite its stabilisation being great.Can anyone advise me hoe to fly at a consistent height above ground level please? I tried flying behind the car and tracking, but for some reason when I started the car moving, the drone did not follow. I have a bit to learn about tracking! Any advice please guys?
 
One of the problems is that the DJI drones do not know where ground level is. All they know is altitude above the launch point. Unless your flying area is perfectly flat the drone will rise or descend relative to ground level depending on how much the actual ground level varies from the altitude at launch.
 
What's the hang up with getting a direct AGL read-out? It doesn't have to be precise. Worst case, you could match GPS position with a digitized terrain map, use height above take-off as a reference, and read out the answer directly.

It just strikes me as odd that such an obviously useful think hasn't been done.
 
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What's the hang up with getting a direct AGL read-out? It doesn't have to be precise. Worst case, you could match GPS position with a digitized terrain map, use height above take-off as a reference, and read out the answer directly.

It just strikes me as odd that such an obviously useful think hasn't been done.
You are not alone.
 
What's the hang up with getting a direct AGL read-out? It doesn't have to be precise. Worst case, you could match GPS position with a digitized terrain map, use height above take-off as a reference, and read out the answer directly.

It just strikes me as odd that such an obviously useful think hasn't been done.
It's not like they can't do it. There is quite a bit at play. DJI is a safety built organization( much to some dismay). They (now) greatly limit what you "Can" do with their drones. Their last drone with full feature set in most categories was the Mavic 2 series. Things improved with tracking and such from there with newer series and releases. Much more was prohibited by them and to third parties.

There are just to many people buying their drones now that basically have no clue what they are doing (Nothing implied to the OP, or you :) ) They just know that the requested feature hasn't been a problem for the more seasoned flyers of their products and responsible pilots as a whole of their market. Nor has enough of their market requested such a feature to require them to implement it.

They don't want a base of non seasoned pilots using their drones in full autonomous mode due to legalities. That is why their more recent offerings don't allow the feature set their earlier versions did. They learned their lesson back when people started doing more...let's just say "Adventurous things" they probably shouldn't of. Remember just because you can, doesn't mean you should. Basically in tracking modes you can manually fly altitude and adjust. If your not flying their stuff as you should be, they want no part of what they can't control in most instances.

DJI sells to the masses and has always held the market, no other company has even come close to what they offer...unfortunately. Is what it is. Also GPS is incredibly inaccurate for height. As no real aircraft uses it for the main system of controlling height.

In almost any aircraft manned or otherwise. Zero height is set at takeoff, and then manually re-zero'd before landing at the landing site all by barometer. DJI has no such feature as it can't call the tower or listen to the broadcast as it changes at any given time. I have taken off with a local flight and landed with my altitude reading 10 foot off with my DJI products in the same spot. Others have reported much further variance.
 
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These drones do not have rangefinders to accurately maintain height. I was able to fly up a hillside that had no trees or tall bushes by using the downward collision avoidance on my M3, but that puts you rather close to the ground. I was trying my hand at search and rescue on a steep slope that had trees where I wanted a constant 100’ AGL and found this to be very challenging. Perhaps GPS could be used instead, but so far I haven’t seen that.
 
Litchi will do this from a pre-programmed waypoint route. It works only if the takeoff point is the same as the takeoff point used in planning the route.

GPS altitude measurements aren't precise enough in the GPS systems used by most consumer products.
 
Litchi will do this from a pre-programmed waypoint route. It works only if the takeoff point is the same as the takeoff point used in planning the route.

GPS altitude measurements aren't precise enough in the GPS systems used by most consumer products.
I have and love Litchi. Waiting for the release to support Mavic 3!!!
 
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absolutely! I am actually considering jumping ship to another brand if DJI don't open the SDK.
Been there! Done that! Regretted it! Autel will never be DJI. They only copy and emulate after the fact, with 1% of the engineers that DJI has. Their claim of no GEO is also complete BS. It is already built into every Autel drone with anti-rollback FW. It isn't compulsory yet, but neither was GEO when DJI first introduced it! Their controllers are a joke, and their software has been years behind DJI! Not a fan. Save your money and enjoy Litchi on the M2P, or find better workarounds for the Mavic 3 and Mavic 3 Pro. Waypoints with LSMC have been a good start towards building in Litchi like features without an SDK.
 
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This is all a bit disappointing. Car, and other object, tracking was one of the main features I was looking for (I haven't yet pulled the trigger).
Has no one found a solution...?
... and how do DJI get away with advertising the feature if it's not available?
 
What's the hang up with getting a direct AGL read-out? It doesn't have to be precise. Worst case, you could match GPS position with a digitized terrain map, use height above take-off as a reference, and read out the answer directly.

It just strikes me as odd that such an obviously useful think hasn't been done.

If sensing and displaying actual altitude above ground level was easy, every small airplane in the world would have that feature. But they don't. They use a barometric altimeter, similar to what drones use.

Equipment to determine AGL altitude is heavy and expensive. Only more sophisticated commercial and military aircraft have such a thing.

Estimating AGL altitude via GPS/map would can provide only gross figures that would be of little real value. And it would involve a ridiculous amount of computer processor time and on-board data storage for the terrain maps.
 
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