Drone Point Cloud Accuracy

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Drone Point Cloud Accuracy

Post by dineshkimraj »

Good day guys.
We have a project where we need to scan a two metre pile located about 51 metres offshore, i.e, the closed we can get to it is 51 metres. We are currently pursuing the idea of using a drone to take pictures of the piles and then create a point cloud. We would then tie in this cloud with our point cloud obtained using a RTC360.

So my question is, what is the accuracy of using the drones (DJI Phantom most likely) to gather the info.

Thanks
Dinesh
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Re: Drone Point Cloud Accuracy

Post by Ioannis »

It depends on the flight height and how you spread gcp imagine that the final mosaic is a table and the legs is gcp. From mine experience with drones you can archived in x,y 3,4 cm and in z from 5cm to 10 cm. But it depends in many other factors..
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Re: Drone Point Cloud Accuracy

Post by stutosney »

Hi Dinesh,

It depends on the camera attached to the drone as well as whether you will have any GCP's for the drone to pick up. I would also be cautious about relying on scan data from an RTC from 50 metres away, though if accuracy isn't a major factor, it should be fine.

Good luck
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Re: Drone Point Cloud Accuracy

Post by ABeckett »

Offshore as in surrounded by water? I feel like that's going to cause issues with the photogrammetry calculation. I'd suggest a highly accurate scanner. Maybe something like the Leica P series.
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Re: Drone Point Cloud Accuracy

Post by MajorDomo »

Coverage is a red herring, you need parallax. moving water=no parallax. Make sure you get some wide shots to add that to the calculation.
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Re: Drone Point Cloud Accuracy

Post by dineshkimraj »

Thanks for the suggestions, using a scanner with a better range might be our best option.
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Re: Drone Point Cloud Accuracy

Post by gsisman »

stutosney wrote: Thu Jul 11, 2019 5:41 am Hi Dinesh,

It depends on the camera attached to the drone as well as whether you will have any GCP's for the drone to pick up. I would also be cautious about relying on scan data from an RTC from 50 metres away, though if accuracy isn't a major factor, it should be fine.

Good luck
If you're using the RTC360 make sure you are having multiple targets onshore about the same distance or maybe 30m from the scanner and they are tied in elevationwise . this will counter the effect of the less accurate non-dual axis compenstor IMU. Are you not able to see all the way around the pile? Is that the purpose of the drone?
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Re: Drone Point Cloud Accuracy

Post by stutosney »

dineshkimraj wrote: Thu Jul 11, 2019 2:02 pm Thanks for the suggestions, using a scanner with a better range might be our best option.
If you need any help, I'll happily pop over to T&T!
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Re: Drone Point Cloud Accuracy

Post by 3DForensics »

I would say you could easily run a test on a known item. Scan it with the RTC and then photograph with drone at same distance as your real project. Compare and you will have a very good accounting of what is possible.

E
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Re: Drone Point Cloud Accuracy

Post by MajorDomo »

Just don't forget to do that test with water surrounding the object. Or mask the ground.
Otherwise you will get a false positive, parallax is the basis of photogrammetry. Water will reduce it severely.
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