Experience with underwater vehicles, drone like flying at 5m altitude

General Help
#1

Hi folks.

Im not sure what Im asking is even possible, only just supported the community through the webODM option and attempted something perhaps not straightforward or normal so fully appreciate help may be difficult to come by.

I have a ROV running lines like a drone at 5m altitude with still images of the seafloor and maybe 60% overlap alongtrack. Ideally I was looking to mosaic to create a larger tiff but have been amazed with the photgaramtery outputs which are great and got more than I expected when conditions are good. When going over some shipwrecks etc and in very clear water the results are so much better than I expected, the 3d reconstruction actually very accurate. Sadly the bulk of the seafloor is nondescript so obviously struggles to stitch.

The thing is I have very good positioning (NO EXIF data), not RTK but close over so I wrote a quick script to create a “geo.txt” file and after some teething problems this is now read and I hope used, certainly I cant see errors and tiffs now appear in the correct place. Unfortunately the bulk of the vehicle track does no get generated.

I have not included Omega, Phi and Kappa values although could if I believe this would benefit me by essentially laying the images done without a match. May take e a minute to work out how to calculate them so wonder if its got a chance of working,

If I include these and when working in areas with bad visibility or no targets (a lot of the seafloor looks identical) will the software trust the geo.txt file enough to just lay the files on top of each other without matches?

As the conditions are bad I dont expect the system to be capable of mosaicking simply georeferencing, or is this something thats not possible?

Thanks for any advice,

Craig.

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#2

Hey @Craig_Wallace, that’s interesting. Could you share some sample images?

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#3

Hi, sure. I have some files but how you want to receive? Any insight would be greatly appreciated,
Craig

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#4

Something like a OneDrive, Google Drive, DropBox, Box.NET, etc so we can take a poke at the data :slight_smile:

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#5

Thanks guys, so maybe here,

https://drive.google.com/drive/folders/1ygBGivGyxsBG4oqXntJgIZ0bN0dsuSJL?usp=sharing

Ive got one folder here called engine. Its an engine on the seafloor. Ive generated a geo.txt file but only populated with lat/long and depth. I have heading (to north) and roll and pitch values for the vehicle on each image but not sure how to transpose to omega phi kappa. I guess heading should be very close as she flys very close to 0 for roll and pitch but otherwise Im not sure how to calculate the correct numbers and didnt seem to do anything.
This engine example you see will come out really nice but I will upload one of a wreck which works on the wreck but the rest of the line is gone.
Thanks Craig

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#6

Hi again. So yeah thats me uploading the small shipwreck now also. Dont get super excited its just an old little craft with a tiny engine but still interesting.

#7

**Sorry I mean altitude in metres not depth

#8

Hi Craig,

I ran the dataset with default settings, it seems to works just fine. I have some concerns on the accuracy of the model, but for general purposes is great.

Photos can be enhanced by adjusting contrast and brigthness, but the best is to improve the mission planning by taking oblique shots of the underwater structures.

Read this for a quick reference. Modelos 3D (dronedeploy.com)

This is just amazing!

Point Cloud

Textured Model

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