Radiometric calibration using the "use sun sensor" option.

[Modesto]

Hello,

I am seeking guidance on the radiometric calibration process using the sunlight sensor option with images acquired by the DJI Mavic 3 Multispectral (M3M) drone. After applying the calibration in the software, I export the data; however, I notice that the final product is still represented in digital numbers (DNs), rather than in physical values such as radiance or reflectance. I would like to know the correct procedure to convert DNs into physical values of radiance or reflectance.

[olihar]

Are you using the raster transform?

Are you using calibration panel? Sun sensor is not enough on its own.

[Alexey Pasumansky]

Hello Modesto,

Please check the "export" section in the following tutorial:
https://agisoft.freshdesk.com/support/solutions/articles/31000148780#Export-the-results

If I understood your request properly, then you need to use Raster Transform section and divide all bands by 32768 value to get each output band normalized to 0 - 1 range. Then in the export dialog select Raster Transform -> Index Value option.

[Modesto]

Hello Alexey,

In this case, when using the "Use Sun Sensor" option and dividing the bands by the value 32768, the resulting normalized values are expressed in reflectance, correct?

I would also like to confirm whether this normalization method (division by 32768) is applicable to any 16-bit image acquired from different sensors, or if it is a procedure specific to MicaSense cameras. I found this reference in materials related to MicaSense; however, I am working with imagery obtained using MAVIC M3M.

[Alexey Pasumansky]

Hello Modesto,

Yes, you need to divide by 32768 for the 16-bit uint images, as after applying reflectance calibration procedure the middle of the values range will be considered as 100% reflectance.

This procedure is not specific to MicaSense and you can use the same for Mavic multispectral drone.

[Modesto]

Thank you very much, Alexey.

Finally, I would like to know if there is any technical document available that describes the steps and calculations involved in the radiometric calibration process using the sun sensor.

[Geomet]

I can't find any technical document explain this process either...