Images of water at a river mouth

[Pirate]

I am trying to put together an ortho of sand banks at a shallow river mouth so the local coast guard can look for a channel to navigate through to deeper water. I am acquiring the images with flights using a multicopter at 300 - 400 feet.

The water is clear enough and shallow enough to see the undulations in the sand under the water. However the images will not stitch together unless there is a land feature in the image. Is there a way around this issue?

[ekbmuts]

Pirate, Short of putting some unmoving markers in the water, I don't know of a quick fix.  I'm no expert at water and land banks and all that but Photoscan will not recognize moving elements, and water is moving all the time and reflecting and essentially changing its form constantly.

Unmoving markers that are anchored to the land under the water would help you.  Then Photoscan could grab those items.  But they can't be floating (and therefore moving) or you will have the same problem as you are currently having.

Maybe someone with some more experience with the type of project that you are trying to do will be able to pass on some tips in addition to mine.

Jon

[grommit]

A more or less standard photography technique with water is to use a linear polarizer set at an angle to block specular reflections. How to control this with a drone is unknown, but certainly possible if you use something like a focus puller on the filter.