Precise elevation change

[toutenhoofd]

I'm about to order a M2P and I'd like to make sure it will meet my needs for a specific project. I would like to be able to hover and take a single photo, then change elevation by a very specific (and relatively small amount, probably 5-6cm) and then take another photo. I'd like to be able to fine tune the vertical change, as accurately as possible, ideally down to about a millimeter. If I calibrate my system and decide that 5.6cm is the right amount of vertical change between photos, I'd like to be able to repeat that, quickly and easily - take a photo, drop or rise 5.6cm and then take another photo.

Can I do this with waypoints? Or is there another way to accurately change elevation by a specific and small amount?

Thanks

 

[Meta4]

I would like to be able to hover and take a single photo, then change elevation by a very specific (and relatively small amount, probably 5-6cm) and then take another photo. I'd like to be able to fine tune the vertical change, as accurately as possible, ideally down to about a millimeter.

If the drone is within range of the downward facing VPS sensors (Up to 10 metres above the ground, you might be able to get 0.1 metre resolution.
But what are you wanting to get from this?
How far from the ground and how far from the subject?

I've tried to picture the viewpoint from various levels of a 40 story building before it was built and found that it's impossible to see any difference at 5 metre intervals with the wideangle lens of the drone.
At 10 metre intervals, the difference is very minor.

 

[Deleted member 103366]

Indoors with the drone 'under my nose' I can get cm adjustments, with an MM and an M2P, but out of doors and presuming at a distance or remotely via the camera view I doubt it is possible.
Like Meta4 I would question whether, out of doors, the perspective change would be noticeable. For it to be noticable I suspect you would need to be very close to the subject and out of doors I think that proximity would be risky.

 

[boblui]

If the height is below 11 meters, it uses the IR sensor at the belly for height measurement. Above that it uses the barometer and GPS. None of these are very precise. From the user manual of Mavic 2 :



If the environment is outdoor and the GPS signal is very good, RTK GPS can meet your requirement. The Phantom P4 RTK has a vertical positioning accuracy of 1.5 cm

 

[toutenhoofd]

This would be done indoors and well below 11 meters. I totally agree that outdoors the perspective difference will not be noticeable unless the subject is very close to the camera. I wish I could control the drone with a raspberry pi, or something like that, to consistently change the elevation by a small and specific amount. Proximity sensors, or using the accelerometer to determine the elevation change seems like it would be way more accurate than purely with GPS. Thanks!

 

[Cymru]

I'm about to order a M2P and I'd like to make sure it will meet my needs for a specific project. I would like to be able to hover and take a single photo, then change elevation by a very specific (and relatively small amount, probably 5-6cm) and then take another photo. I'd like to be able to fine tune the vertical change, as accurately as possible, ideally down to about a millimeter. If I calibrate my system and decide that 5.6cm is the right amount of vertical change between photos, I'd like to be able to repeat that, quickly and easily - take a photo, drop or rise 5.6cm and then take another photo.

Can I do this with waypoints? Or is there another way to accurately change elevation by a specific and small amount?

Thanks

No chance with that. Barometric altitude isnt accurate enough (and tends to drift during a flight) and GPS altitude is even less altitude again.

Very roughly GPS altitude absolute is about 1.5x horizontal error so could easily be 3-4m out.


The nearest you're going to get is 10x the figure you're after in terms of accuracy on a M2.

You're going to need an RTK equipped drone to do anything like this (and even then im not sure they can reliably FLY at that accuracy, simply report where they are)

 

[Deleted member 103366]

Perhaps if, without giving away secrets, you told us what you are trying to photograph one of us might be able to try and duplicate your situation. Incidentally I do not get GPS lock indoors.
I have just had an M2P climb an 18" ruler in roughly 2" increments, via the joystick and screen, using the VPS for position holding but in all honesty there was some lateral movement which might have been caused by loose stuff on the floor flapping in the downdraught so whether it would be suitable I do not know. I can try it with a MM if you like.
Would a normal camera on a rigidly held pole and a remote trigger not work?

 

[Meta4]

No chance with that. Barometric altitude isnt accurate enough (and tends to drift during a flight) and GPS altitude is even less altitude again.

The Mavics don't use GPS for altitude control, just horizontal positioning.
Vertical stability comes from either the barometric sensor or VPS
The specs for the Mavic 2 show:

Hovering Accuracy Range ​

Vertical:​

± 0.1 m (when vision positioning is active)​

± 0.5 m (with GPS positioning)​

Horizontal:​

± 0.3 m (when vision positioning is active)​

± 1.5 m (with GPS positioning)​

You're going to need an RTK equipped drone to do anything like this (and even then im not sure they can reliably FLY at that accuracy, simply report where they are)

RTH isn't going to work well indoors.
But here are the relevant specs for the Phantom 4 RTK

Hover Accuracy Range ​

RTK enabled and functioning properly：​

Vertical：±0.1 m；Horizontal：±0.1 m​

 

[toutenhoofd]

No real secret here...

With the Insta360 One R drone mount, there are two cameras, one above the drone and one below. I would like to be able to take one photo with the top camera, pointed toward the ceiling, then raise the drone the exact distance between the two cameras so the bottom camera is now where the top camera was, and then take a second photo pointed down. This will allow me to stitch the two images together for a spherical panorama with zero parallax between the two images. Outside, where the world is far away, this is entirely unnecessary. But for shooting spherical panoramas (still panoramas) indoors, like for real estate, the two cameras are way too far apart.

I don't care about the exact position of the first photo - I can just fly the drone to the place where I want to shoot it. But the second photo is the tricky part. I can nudge the drone up and get it pretty close, just by eyeballing it, and that will be way better than not moving the drone at all, but I'd rather press a button and have the drone go up (or down) the right amount and then resume a hover.

Make sense? I've attached a photo in case people don't know what the Insta360 drone rig looks like.

Thanks.

 

[Cymru]

The Mavics don't use GPS for altitude control, just horizontal positioning.
Vertical stability comes from either the barometric sensor or VPS
The specs for the Mavic 2 show:

Hovering Accuracy Range ​

Vertical:​

± 0.1 m (when vision positioning is active)​

± 0.5 m (with GPS positioning)​

Horizontal:​

± 0.3 m (when vision positioning is active)​

± 1.5 m (with GPS positioning)​

RTH isn't going to work well indoors.
But here are the relevant specs for the Phantom 4 RTK

Hover Accuracy Range ​

RTK enabled and functioning properly：​

Vertical：±0.1 m；Horizontal：±0.1 m​

They do reference absolute GPS for EXIF tagging.

The accuracy range is position keeping which isnt the same thing as holding an exact position within strict tolerances. The barometric often drifts 10+ft in the space of a flight as the device warms up as well.

Ultimately theres nothing on a mavic 2 thats going to provide anything near 5cm levels of fine control or position keeping.

 

[Meta4]

They do reference absolute GPS for EXIF tagging.

Although the drone is recording GPS altitude for the complete flight, it doesn't use GPS for Vertical positioning.
They do have a field in the Exif data that is labelled GPS Altitude and in at least that comes from GPS (now but not in the early days).
And just to confuse everyone, for most DJI drones, the Exif "GPS data" doesn't come from GPS at all.
But that's another story.

Ultimately theres nothing on a mavic 2 thats going to provide anything near 5cm levels of fine control or position keeping.

That's exactly right.

 

[boblui]

I did this test with my M2P the other day indoor. The drift in horizontal position was +/- 3cm with vision positioning. This is probably the best precision the OP can realistically achieve :

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The biggest problem in the set up shown in OP's post #9 is that the bottom sensors will be mostly blocked so vision positioning / IR distance sensing will likely not be working

 

[toutenhoofd]

I did this test with my M2P the other day indoor. The drift in horizontal position was +/- 3cm with vision positioning. This is probably the best precision the OP can realistically achieve :

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The biggest problem in the set up shown in OP's post #9 is that the bottom sensors will be mostly blocked so vision positioning / IR distance sensing will likely not be working

That’s a great point you bring up about the bottom sensors being blocked. There’s a disclaimer on the Insta360 website that says “The Aerial Edition only works with flying drones in ATTI mode, which requires extensive professional experience. Non-professionals are not recommended to purchase this Edition, as they may bear the risk of damages during flight.”


Thanks