How to [Raw > Rad. > Ref.] data values

#1

Hi everybody,
New to this forum.

I’m trying to support a partner with Sequoia imagery for agriculture analytics by using open-source processing chain (not pix4d). Practically, I’m trying to better understand the following:

1 - Are raw data units already normalized to the downwelling irradiance sensor readings? (e.g. in a given TIF file of a single spectral band)

2 - If we need to normalize the data to reflectance ourselves, is the following calculation per spectral band and per exposure time [reflectance=(raw-dark)/irradiance] sufficient, or you rather recommend another calculation?
(i.e. - do the units for radiometric calibration take into account raw-to-radiance conversion?)

3 - What are the units of the irradiance sensor’s values in the EXIF? (e.g. [W m-2 sr-1 nm-1])

4 - Which of the irradiance.List lines in the EXIF should we use?

5 - Any other EXIF fields’ values and calculation we need to take into account on that matter?

It is not clear to me if the various answers at this forum are in line with official parrot support…

If any of you have some/all answers, your advice will be greatly appreciated.
Cheers!
Tal

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#2

Hi @Tal

All your questions have already been discussed at large in the forum.
I suggest that you take time to read the discussions.

Cheers

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