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Author Topic: Large Area RedEdge3 Project  (Read 868 times)

tdwitt

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Large Area RedEdge3 Project
« on: July 22, 2020, 05:31:03 PM »
I am working on a project where we mounted a RedEdge3 to a manned aircraft to map a large watershed and two streams. The imagery was captured at ½ meter GSD. Since we mapped such a large area, to conserve storage space, we disabled the RedEdge band and captured the imagery in the DNG format (though the images still show up as .tif files). The imagery was captured over four days with two flights each day (morning & afternoon) to avoid the sunspot/hotspot window around solar noon and when the sun was 30 degrees above the horizon (to minimize long shadows). The final complicating factor is that we could not fit the GPS in the mount holding the RedEdge3, so none of the images have timestamps or GPS metadata. Without the geotags and to help keep the imagery organized, I added prefixes to the imagery with the flight and subfolder information, which allows me to use the “sequential” setting when aligning the images in Agisoft Metashape. I am mostly having good luck, but some images are not aligning. I am going to keep playing around with the align settings, but my last resort will be to align the images by placing markers manually.

The last thing I am wonder is how I should implement the reflectance calibration. I captured images of the calibration panel before and after each flight. Should I calibrate each flight individually with these before & after calibration images and then merge the flights into a single project? Will there be issues with the calibration since these flights were so long (about 3 hours), and therefore the solar elevation changed quite a bit during the flight? It would be great to have a more technical description of the calibration process and science behind it.

I recognize this is an unconventional use of your sensor, so I understand if some parts of the project don’t work out. However, please let me know if you have any tips or tricks that I could try out!