Bright and Cloudy Dark Spots in Orthomosaic After Reflectance Calibration

[Geomet]

Hello,

I am experiencing an issue with bright and cloudy dark spots appearing in my orthomosaic after processing. The problem seems to originate from reflectance calibration, as I notice similar brightness/darkness inconsistencies in the individual images immediately after calibration.

When I zoom into the orthomosaic, I can see that the shadowy areas appear as polygonal-shaped regions. I am skeptical that this issue is related to cloud cover, as all my other surveys have been conducted under a range of cloud conditions without any issues.

I am using a DJI Mavic 3M multispectral drone and a MicaSense reflectance panel. I follow the same workflow for all 20 surveys I’ve processed, but this issue is only appearing in three of them.

I manually Calibrate reflectance  by placing the panel images in the separate image group (Note: The Mavic 3M has a sun sensor, but it fails to calibrate irradiance on about 1/3 of the images for every survey I’ve done. Enabling or disabling the sun sensor does not seem to affect this issue).

The same workflow works fine for other surveys, but for the three problematic ones, I see this issue persist despite consistent settings and processing steps.

I’ve attached screenshots of the shadowy polygons in a reply to this message

Does anyone have insight into what could be causing these bright and dark spots in the orthomosaic? I’d appreciate any suggestions or recommendations! Thanks!

[Geomet]

Here are screenshots of the issues.