SARCalibration How LUT choice should be interpreted?

OTB Usage
1

Hi,

In the Description section of SARCalibration it is written that:
“This application allows computing Sigma Naught”
And for calculation of this Sigma Naught there it is said that there are 4 LUT choices available at product metadata : [sigma,gamma,beta,DN]

Questions:

  1. The calibrated data is “SigmaNaught” no matter which LUT we use? or depending on the selected LUT, we have to call the output(calibrated) data, GammaNaught, BetaNaught etc. ?

  2. what are the interpretations of choosing one of the 4 available look-up-tables for production of Calibrated data ?

As a test case I chose a sentinel-1 IW GRD product and calibrated the HV-polarization product 4 times with each one of these options then for the output product I ploted the histogram of the calibrated product. The respective histograms practically look the same. Also the statistics (mean, median, std, min, max) are also very close to each other!

I would appreciate any comment on this

2

https://www.researchgate.net/post/What_is_radiometric_calibration_of_Synthetic_Aperture_Radar_Data

3

Thanks, I have checked that conversation page. But it does not provide a clear information regarding my questions. It is a good definition of what radiometric calibration is. What I want however is to use the LUTs provided for each SAR product together with the calibration information provided as .xml files within each SAR product and calculate the calibration on my own in order to fully understand the underlying process of calibration.