Issue with Reflectance Calibration on DJI Mavic 3M Multispectral Images

[Geomet]

Hi everyone,

I am encountering an issue with reflectance calibration in Metashape, and I would appreciate any insights or advice.

I am using a DJI Mavic 3 Multispectral drone along with a MicaSense calibration panel. I have followed the recommended steps for manual reflectance calibration sense the panel is not automatically detected.


This process worked perfectly for one of my surveys. However, when I tried to calibrate reflectance for subsequent surveys, only a portion of the images gets calibrated, while the rest remain uncalibrated.

As a result, the orthomosaic ends up with inconsistent colors, and the imagery is essentially unusable—colors are completely off, making it very difficult to interpret or analyze.

Has anyone else experienced this issue or know what might be causing it?

[Alexey Pasumansky]

Hello Geomet,

It is important that the calibration images with the panel are present in the same camera calibration group (in Tools Menu -> Camera Calibration dialog) and that mask is applied properly to each band of the calibration images before Calibrate Reflectance operation is started.

Can you share screenshots of Camera Calibration dialog and Calibrate Reflectance dialog?

[Geomet]

Hello,

Thank you for your quick reply!

I’ve attached screenshots of the Calibration Reflectance dialog and the Camera Calibration dialog.

Note, that I do mask out the reflectance panel itself for each of the bands before running the reflectance calibration

I’ve enabled the Sun Sensor option, but, it failed on approximately 600 of the 3000 images. Additionally, only about 2500 of the 3000 images were successfully calibrated for reflectance. The resulting orthomosaic can also be seen in the screenshot.

Thank you

[Alexey Pasumansky]

Hello Geomet,

According to the screenshot you have three calibration groups. If you leave all three, then calibration images with the applied masks should be present in all three groups.

[Geomet]

Hello, thank you again for your help!

I’ve duplicated the reflectance panel image (e.g., loaded it into my workspace) two additional times, so now there are three instances of the same reflectance panel image. I applied the mask to all bands in all the images and manually added a reflectance panel photo to each of the three camera groups.

However, not all images and bands were calibrated successfully (see screenshot: "IncompleReflectanceCal.png"), even when the reflectance panel photo exists within the same camera group. The issue seems to occur mostly (or exclusively) with the RGB images (see screenshot #2: "rgb_not_cal.jpg").

Do you have any idea what might be causing this issue? Why are multiple camera groups automatically created—is it due to the large number of images in this survey? Additionally, can these camera groups be combined into a single group to simplify the calibration process?

Thank you again!