Hello. I merged two multispectral projects into one (flights/image acquisitions for these two projects were done on different (but consecutive) days with eBee drone and Sequoia multispectral camera). Merger was done after processing step 1 and marking some MTPs with the same name in each. But further processing steps (2 and 3) were not successful. got the warning message:[Warning]: Unable to estimate direct sunlight fraction: The sun is behind the horizon. Any idea what could be the reason? unfortunately could not find the report in the project folder.
To get the sun position, the software will use the position and the time of the day. It could be that the time is not correctly written in the EXIF. Could you please share an image or two from this flight, for which the warning is shown. We will have a look to see if the necessary information is there.
Please note that Pix4D expects Exif.GPSInfo.GPSTimeStamp to be in UTC time and not the local time. The time is only needed for the sun angle correction. As such, for the already captured images there are two workarounds:
1- Ignore the sun angle correction and choose Camera and Sun irradiance in the radiometric corrections: https://support.pix4d.com/hc/en-us/articles/203891879#label3
2- Change the GPSTimeStamp in the EXIF of the images. This would require you to write in the EXIF and change the time from local to UTC.
This issue might be a firmware issue, for future flights, indeed please consider updating the camera to the latest firmware version