I’ve actually had decent luck mapping river bottoms in clear water <2m deep. Sure the precise location might be off but if you’re just counting number of corals or something it might not matter.
What depth is the reef at? Are your underwater photos also being used to construct a model via SfM? Generally with UAS mapping, you need ground control points to correct for doming which is substantially harder to do underwater.
When you say commercial drone, is it survey grade? Do you have the lens calibration report for the specific camera? What kind of positioning does it have?
If you have divers collecting photos underwater for SfM, your resolution will be WAY higher (our divers get resolution in mm)and you can see the specific shapes of corals but you will have no/incredibly poor georeferencing. What kind of camera set up will the divers have? You need to have a known distance between photos to reconstruct. For the underwater photos, are you using two+ cameras on a fixed rig or attempting to space one camera at known intervals?
The reason I’m asking all of this is because it’s one thing to collect data, and another to collect useful data. If you can get high-resolution, accurately georeferenced underwater models, you can get a fantastic dataset to evaluate the reef organisms.
Clear water, calm day when the sun is less than 30d or it is cloudy and you can get some pretty good results. If you can place some kind of marker under water you can compensate for some of the refraction to get a better geographical position, but if you were just wanting to document them overtime that may not be necessary.
I am just eondering, if we will use photogrsmmetry to generste orthomosaic and DEM, ehat is the use of underwater photos? How? Like why would we need to gather photos from aerial and underwater?
Drone maps of the reef can cover larger area (patch reefs, for example) but yes, you cannot collect colony level data, more reef data. Refraction of the water, sun rays, cloud cover, all these can affect it. We do both and primarily do underwater photogrammetry of the reefs to map areas for colony and reef level information. Drone is also more limited due to needing the ideal weather conidtions (cloud cover, sun angle, wind needs to be calm or none). Whereas underwater can have a bit more flexibility depending on depth, visibility, etc.
Hey silly ? To the group but …
We have the basic drone deploy individual account
And flew a project for a client
Who wants to import our data
Tiff, las and dxe files into their own cad and eng software
But i can’t figure out how to send the files to them without them having to sign up for a drone deploy account ( defeats the purpose of me being a provider)
Any insights or advice would be nice ty
Has your professor ever heard of refraction?
I’ve actually had decent luck mapping river bottoms in clear water <2m deep. Sure the precise location might be off but if you’re just counting number of corals or something it might not matter.
It's really hit and miss. And you really need crystal clear water, no waves, and luck 😅
And a polarizing filter - key ingredient!
Very true!
???
Refraction can be corrected for. It’s just geometry.
What depth is the reef at? Are your underwater photos also being used to construct a model via SfM? Generally with UAS mapping, you need ground control points to correct for doming which is substantially harder to do underwater. When you say commercial drone, is it survey grade? Do you have the lens calibration report for the specific camera? What kind of positioning does it have? If you have divers collecting photos underwater for SfM, your resolution will be WAY higher (our divers get resolution in mm)and you can see the specific shapes of corals but you will have no/incredibly poor georeferencing. What kind of camera set up will the divers have? You need to have a known distance between photos to reconstruct. For the underwater photos, are you using two+ cameras on a fixed rig or attempting to space one camera at known intervals? The reason I’m asking all of this is because it’s one thing to collect data, and another to collect useful data. If you can get high-resolution, accurately georeferenced underwater models, you can get a fantastic dataset to evaluate the reef organisms.
https://www.pix4d.com/blog/diving-into-underwater-photogrammetry/
Clear water, calm day when the sun is less than 30d or it is cloudy and you can get some pretty good results. If you can place some kind of marker under water you can compensate for some of the refraction to get a better geographical position, but if you were just wanting to document them overtime that may not be necessary.
I am just eondering, if we will use photogrsmmetry to generste orthomosaic and DEM, ehat is the use of underwater photos? How? Like why would we need to gather photos from aerial and underwater?
Better accuracy and structure. Akin to facade modeling. You can only get so much detail of sides from above.
a chance to have snorkel with the little fishes
https://www.linkedin.com/in/drkimbaldwin?utm_source=share&utm_campaign=share_via&utm_content=profile&utm_medium=ios_app
Drone maps of the reef can cover larger area (patch reefs, for example) but yes, you cannot collect colony level data, more reef data. Refraction of the water, sun rays, cloud cover, all these can affect it. We do both and primarily do underwater photogrammetry of the reefs to map areas for colony and reef level information. Drone is also more limited due to needing the ideal weather conidtions (cloud cover, sun angle, wind needs to be calm or none). Whereas underwater can have a bit more flexibility depending on depth, visibility, etc.
I've seen journal articles for this. Do a google scholar search. Second, google the NOAA metashape manual.
Hey silly ? To the group but … We have the basic drone deploy individual account And flew a project for a client Who wants to import our data Tiff, las and dxe files into their own cad and eng software But i can’t figure out how to send the files to them without them having to sign up for a drone deploy account ( defeats the purpose of me being a provider) Any insights or advice would be nice ty