Hi, we've been using p4ms at different irradiation levels and found that IrradianceExposureTime and IrradianceGain are always stable. I can find images of the same object (reference panel) taken in May and October having the same Irradiance (or SunSensor) values but 3 times different camera exposure times (same camera gain) giving different camera values. Data from irradiance sensor and camera sensor over a known target should be related, how come they aren't? Are stable IrradianceExposureTime and IrradianceGain really a feature or is this a bug? If this is a bug, do I have the real values of these two parameters stored somewhere in the raw data of an image and can I retrieve them? I'll appreciate your help. K.

Hi, you can check every pictures value with Exiftool https://www.exiftool.org/

Hi, thank for your answer!
Yep, I have read the XMP metadata before (with different tools).
Across missions, Irradiance data is changing for me but IrradianceExposureTime and IrradianceGain don't. And my data indicate that they should be changing.
Since you are a p4ms user, could you please check if these parameters are stable or variable across your missions?

I will also appreciate manufacturer's answer.  

kriskus Posted at 8-24 00:10
Hi, thank for your answer!
Yep, I have read the XMP metadata before (with different tools).
Across missions, Irradiance data is changing for me but IrradianceExposureTime and IrradianceGain don't. And my data indicate that they should be changing.

Don't hold your breath on a meaningful response from DJI here...

I'll try to look at some of my data when I can.

kriskus Posted at 8-24 00:10
Hi, thank for your answer!
Yep, I have read the XMP metadata before (with different tools).
Across missions, Irradiance data is changing for me but IrradianceExposureTime and IrradianceGain don't. And my data indicate that they should be changing.

On my pictures it's the same thing. But Exposure time and Radiometric Calibration are changing. Why do you think the irradiance settings should change?

LV_Forestry Posted at 8-29 00:00
On my pictures it's the same thing. But Exposure time and Radiometric Calibration are changing. Why do you think the irradiance settings should change?

OK. Thanks. Radiometric Calibration looks stable within a single band to me. Again, I was measuring reference panel on different days and different weather and got different relation between irradiance sensor and camera data when calculating using formulation suggested by DJI. Was looking for the source of variability.
  

kriskus Posted at 8-31 02:23
OK. Thanks. Radiometric Calibration looks stable within a single band to me. Again, I was measuring reference panel on different days and different weather and got different relation between irradiance sensor and camera data when calculating using formulation suggested by DJI. Was looking for the source of variability.

The famous story of reflectance panel with phantom 4 multispectral ! There are some post about this on this forum.