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Altitude not repeating on saved hyperlapse waypoint mission - Air 3

KenG

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I need help regarding altitude on a saved hyperlapse waypoint mission.

Today I wanted to fly 3 missions back to back to back changing only the interval on a saved mission to see how it affected the result.

First battery: I flew to first waypoint at 300 feet, selected it and made all camera selections for exposure, gimbal, etc. and then flew to second waypoint, also at 300 feet and made all selections. I set interval and video length and then saved the mission to the library. I flew back to the homepoint, landed and changed to a fully charged battery.

Second battery: After changing to this second battery, I took off, after allowing for the home point to be updated and flew up to about 20 feet above the home point and selected my saved mission. The aircraft headed for the first waypoint but only to 282 feet. It ran the mission staying at 282 feet. After completion, I flew back to the same homepoint and changed to battery number 3.

Third battery: Taking off from the same homepoint and selecting the same saved waypoint hyperlapse mission, I changed only the interval from the previous mission from 6 to 7 seconds and started the mission. This time it flew to the first waypoint but only to 252 feet. I left it alone to run the mission and when completed I let it fly to the same waypoint where I changed to batter 4.

Fourth battery:Taking off from the same homepoint and selecting the same saved waypoint hyperlapse mission, I changed only the interval from the previous mission from 7 to 5 seconds and started the mission. This time it flew to the first waypoint but only to 217 feet. I left it alone to run the mission and when completed I let it fly to the same waypoint where I had started each mission.

What could I be doing that doesn’t let the aircraft return to the same altitude each time I select the saved mission? I didn't think it was a huge deal to go from 300 to 282 feet but them to 252 and finally 217? The takeoff point was the same spot each time and the only pause between all flights was the time it took to change batteries. I didn't even pick up the aircraft but changed the battery exactly where it was landing and taking off.
 
Weird... did you review the waypoints on any of those flights after loading from storage and see what the altitudes were? I'd expect 300, but then that's not where it's flying.

Don't have an A3, but I'll give it a test with the Mini 4P and see what happens.

You might want to do a test run with regular waypoints and see if it's having problems there too.

Finally, could be a flaky barometer... how well does it hold altitude just flying it around slowly? You could even lock a circular path at low speed with cruise control and watch go around and around for a while, checking how well it's holding altitude. If the barometer is flaky, it might manifest there.
 
Weird... did you review the waypoints on any of those flights after loading from storage and see what the altitudes were? I'd expect 300, but then that's not where it's flying.

Don't have an A3, but I'll give it a test with the Mini 4P and see what happens.

You might want to do a test run with regular waypoints and see if it's having problems there too.

Finally, could be a flaky barometer... how well does it hold altitude just flying it around slowly? You could even lock a circular path at low speed with cruise control and watch go around and around for a while, checking how well it's holding altitude. If the barometer is flaky, it might manifest there.
I don't know how to review the waypoint altitudes from the stored/saved missions. I may have learned incorrectly but my understanding is fly to the spot where you want to save the waypoint, make all adjustments for camera and gimbal and save that waypoint and it also saves the altitude. Then do the same for all waypoints to be included, which also allows for altitude change, if desired, but in this case I maintained the same 300 feet for waypoint 2 when setting up and storing the initial course.

If my procedure is incorrect and/or someone can tell me how to review/confirm the altitudes, please let me know. I have now had a chance to review the footage and although I can't tell from watching what the altitudes were, I can clearly see on each video that the drone was lower than the previous.
 
Droning on and on...
I've just gone back through the manual and I see where altitude, among other things, can be selected in waypoint video but in waypoint hyperlapse the only selections are: normal or reverse sequence, interval, and vid length. I don't find in the manual any mention of altitude one way or the other in the section on waypoint hyperlapse so now I'm not sure where I got the idea that the altitude is saved. However, if there is no saving of altitude in waypoint hyperlapse, it puts a serious cramp in a saved waypoint hyperlapse route.
 
Probably the difference between hyperlapse waypoint and a regular waypoint mission, where the altitude is saved.
 
Probably the difference between hyperlapse waypoint and a regular waypoint mission, where the altitude is saved.
I still believe something is wrong here and will continue researching it. I've seen a number of vids for day to night hyperlapse where the mission is saved on battery one, flown on battery two and then after dark flown again. Then an edit is performed to put the two vids together at about midpoint or some other point to blend them smoothly. If the altitudes were all over the place, I believe it would be noticeable.
 
Why didn't I go out and investigate/test this yesterday when it wasn't raining? Why am I so lazy sometimes?

Anyone know?

(climbing into Nomex suit)
 
Droning on and on...
I've just gone back through the manual and I see where altitude, among other things, can be selected in waypoint video but in waypoint hyperlapse the only selections are: normal or reverse sequence, interval, and vid length. I don't find in the manual any mention of altitude one way or the other in the section on waypoint hyperlapse so now I'm not sure where I got the idea that the altitude is saved. However, if there is no saving of altitude in waypoint hyperlapse, it puts a serious cramp in a saved waypoint hyperlapse route.

Well, maybe not. We need to nail down what altitude it uses. If the waypoints don't contain and altitude it stands to reason it flies at whatever altitude its at when you start the Hyperlapse sequence.

Which seems pretty easy to manage... if you don't already keep a notebook and pencil as part of your flight gear, I highly recommend it. You have no idea what may come up on a flight outing that you want to remember at some future time. Here's a perfect example.

Name and save the mission in Fly, keep a table in your notebook with mission names and altitudes. Easy, problem solved.

Nothing fancy, mine's one of those cheap 4x6" ruled, spiral bound from the drugstore. Have had it 6 years when another hobbyist pulled one out and I went,

Homer-Simpson-Doh.jpg
 
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Well, maybe not. We need to nail down what altitude it uses. If the waypoints don't contain and altitude it stands to reason it flies at whatever altitude its at when you start the Hyperlapse sequence.

Which seems pretty easy to manage... if you don't already keep a notebook and pencil as part of your flight gear, I highly recommend it. You have no idea what may come up on a flight outing that you want to remember at some future time. Here's a perfect example.

Name and save the mission in Fly, keep a table in your notebook with mission names and altitudes. Easy, problem solved.

Nothing fancy, mine's one of those cheap 4x6" ruled, spiral bound from the drugstore. Have had it 6 years when another hobbyist pulled one out and I went,

Homer-Simpson-Doh.jpg
Thanks for the tip and I actually have been taking notes (camera settings, ISO, shutter speed, interval if hyperlapse,filter if used, etc ) but not to the extent to include altitude as I hadn't needed that info until now. Additionally I had sent a request to DJI in regard to what I experienced. Their answer:

When saving the task in the Task Library and executing the task, the altitude used is the altitude measured by the barometer, which is easily affected by many factors such as weather and may have a deviation.

Ok, so that told me it saves the altitude the on board barometer measures when the mission is saved and executed. So, I can understand some changes when the barometric pressure changes. However, from my original post, remember I flew 3 missions, back to back to back over a period of one hour only stopping long enough between missions to change the battery. So to start at 300 feet with a saved mission and then fly 3 missions from the saved flight at 282, 252, and then 217 feet makes me think that would've had to be a very rapidly falling barometer.

However, I may have found the problem. I decided to recalibrate the compass (aircraft and controller) and the IMU. Now mind you the controller was tellling me the calibrations were normal i.e. not requiring calibration. Today I took my older Air 2 and the Air 3 (this is the one with the altitude repeat problem) out to see what would happen.

I put up the Air 3 first to 300 feet saved and executed a waypoint hyperlapse and it stayed at 300 feet. Bravo. I landed and did the same with the Air 2 and it gave me the same good results. I flew the Air 3 again using the same original saved mission. From the takeoff point I ascended to 150 feet and hit the red button to execute the mission and she flew to the first waypoint ascending to 300 feet and remained there for the duration of the mission. I did the same thing to the Air 2 and the Air 3 two more times and both nailed 300 feet (within 2 to 3 feet) each time. I also recorded the barometer setting as reported by airports near me so I can see just how much affect changes will have on saved missions. Most airports (towered and non-towered) have phone numbers you can call and listen to recordings to give you that data.

Sorry for the long post. I have learned a lot with this and just wanted to share in the event it helps anyone else.
 
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Thanks for the interesting topic as I'm just stating to investigate hyperlapses with my new Air 3.

I read this thread a couple of days ago and and have since seen a couple of videos where people did the day into night thing and they never seemed to match up very well.

I've since watched this video by Billy Kyle who seem to suggest its a long standing bug.

See from 12:20 here - How To Take EPIC Hyperlapses With Your Drone - Full Tutorial
 
Thanks for the interesting topic as I'm just stating to investigate hyperlapses with my new Air 3.

I read this thread a couple of days ago and and have since seen a couple of videos where people did the day into night thing and they never seemed to match up very well.

I've since watched this video by Billy Kyle who seem to suggest its a long standing bug.

See from 12:20 here - How To Take EPIC Hyperlapses With Your Drone - Full Tutorial
Thanks for the link. Yes, Billy Kyle does excellent work and I have seen a number of his videos although I had not seen this one. And today I learned he is absolutely correct.

I went out today to fly the same saved route as yesterday which was to fly to the first waypoint at 300 feet. To my initial surprise, the aircraft took and headed for waypoint one, blew through 300 feet and stopped at my max set altitude limit of 393 feet. Whaaaat???? Now what.

Ok, yesterdays altimeter setting for barometer was 30.26 and todays is 30.43, a difference of .17. We know for every .02 of change on an aircraft altimeter the difference is 20 feet or 10 feet per .01. So for the increase of .17 the aircraft had to get 170 higher to satisfy the value the aircraft saved for altitude when I set 300 as my altitude yesterday when the barometer was 30.26. Of course it could not reach 470 feet with the limit set to 393 feet.

I'm going to mess around with it more at lower altitudes to see what happens but this is getting a whole lot deeper than I intended.

Thanks (I think, haha) to Droning on and on.......... for pushing me to collect all the details.
 
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I’m not familiar enough with my new drone yet but its seems to set height from take off position rather than barometric pressure above sea level.

Seems like a simple fix for DJI to use take off height rather than total reliance on the registered pressure at the time of the original flight which changes by the hour.

The drone must calibrate itself on startup to the current atmospheric pressure as zero meters/feet so this must be the most accurate and more importantly, safest calibrated height measurement to use rather than pressure, an ever changing positional goal post.

Or am I miss understanding this?
 
I’m not familiar enough with my new drone yet but its seems to set height from take off position rather than barometric pressure above sea level.

Seems like a simple fix for DJI to use take off height rather than total reliance on the registered pressure at the time of the original flight which changes by the hour.

The drone must calibrate itself on startup to the current atmospheric pressure as zero meters/feet so this must be the most accurate and more importantly, safest calibrated height measurement to use rather than pressure, an ever changing positional goal post.

Or am I miss understanding this?
You are 100% correct that height is set from take off position. I started the discussion because I wanted to do a day to night hyperlapse and all of the vids I have seen say to set up the mission, fly it and save it to then again fly at dusk or dark. My expectations were it would not only go to the same saved waypoints but fly the same altitude so I could assemble a nice looking day to night in post.

Going back to my original post, just trying to see the resultant affect lengthening the interval on a hyperlapse would have, I flew three back to back to back missions, only changing the interval from 5 to 6 and then to 7 seconds. I flew them all within a shade over an hour from the exact same takeoff point only shutting down long enough to change the battery. Read my initial post at the top and you'll see that all three missions flew at lower and lower and lower altitudes and it threw me a real curve. I used 300 feet to avoid some obstacles in the area but when I fly later when it is dark and the drone flys 100 feet lower and runs into something, I have a problem. And I'm thinking it is going to fly to 300 feet which I set in the original saved mission but it may or may not.

To your and Billy Kyle's point, this is a worthless exercise. Hope this all makes sense.
 
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You are 100% correct that height is set from take off position. I started the discussion because I wanted to do a day to night hyperlapse and all of the vids I have seen say to set up the mission, fly it and save it to then again fly at dusk or dark. My expectations were it would not only go to the same saved waypoints but fly the same altitude so I could assemble a nice looking day to night in post.

Going back to my original post, just trying to see the resultant affect lengthening the interval on a hyperlapse would have, I flew three back to back to back missions, only changing the interval from 5 to 6 and then to 7 seconds. I flew them all within a shade over an hour from the exact same takeoff point only shutting down long enough to change the battery. Read my initial post at the top and you'll see that all three missions flew at lower and lower and lower altitudes and it threw me a real curve. I used 300 feet to avoid some obstacles in the area but when I fly later when it is dark and the drone flys 100 feet lower and runs into something, I have a problem. And I'm thinking it is going to fly to 300 feet which I set in the original saved mission but it may or may not.

To your and Billy Kyle's point, this is a worthless exercise. Hope this all makes sense.
Indeed, perfect sense.

How do we bring DJI's attention to this issue. Have you tried?

I was also thinking of setting up a circular waypoint mission (normal video) to show the progress of a friend housing development project over several months, documenting the construction of each property and landscaping that I could seamlessly blend together. However this bug (?) seem to put a full stop on that little project.

Big shame....
 
Indeed, perfect sense.

How do we bring DJI's attention to this issue. Have you tried?

I was also thinking of setting up a circular waypoint mission (normal video) to show the progress of a friend housing development project over several months, documenting the construction of each property and landscaping that I could seamlessly blend together. However this bug (?) seem to put a full stop on that little project.

Big shame....
I did bring it to DJI's attention and this was the response.

When saving the task in the Task Library and executing the task, the altitude used is the altitude measured by the barometer, which is easily affected by many factors such as weather and may have a deviation.

That statement is what has led me further down this path. Your project may be just fine. Others have commented the problem I'm experiencing doesn't happen with a saved waypoint video. Perhaps it only has to do with hyperlapse waypoint. I would be interested in what you experience.

This has also led me to experiment and learn more but is sure would be easier to speak with a DJI engineer or anyone who could actually answer specific questions. What good is it to set up a nice route during the day when I can clearly see where everything is, save it and then go back later after sundown and launch the saved mission only to have it flown at a lower altitude and crash?
 
This is brain dead, DJI.

I can guess what the clever engineer was trying to do: Make the mission independent of takeoff location. Was obviously not an actual pilot, nor was this run by anyone with a cert. The need to account for weather impact (i.e. "setting the altimeter") would have been spotted immediately.

Just make it work like all the other height references in the system, DJI. Make it work like the waypoints feature on the Mavic 3, Air 3 and Mini 4 Pro. Add the height parameter to the Hyperlapse waypoints and make it user adjustable.

You're being too clever by half here, DJI, and confusing smart people.
 
This is brain dead, DJI.

I can guess what the clever engineer was trying to do: Make the mission independent of takeoff location. Was obviously not an actual pilot, nor was this run by anyone with a cert. The need to account for weather impact (i.e. "setting the altimeter") would have been spotted immediately.

Just make it work like all the other height references in the system, DJI. Make it work like the waypoints feature on the Mavic 3, Air 3 and Mini 4 Pro. Add the height parameter to the Hyperlapse waypoints and make it user adjustable.

You're being too clever by half here, DJI, and confusing smart people.

Amen!

Did you get a chance to experiment with your Mini 4P? Just curious as I would love to know if others are having such difficulties in repeating an altitude on a saved waypoint hyperlapse. I intend on trying a waypoint video (not hyperlapse) to see if I get the same irregularities but everything I'm supposed to be doing is falling so far behind that I may need to let this problem set for a while.
 
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