I have a question about exporting calibrated TSX images from Snap. I need to use them to analyze the RCS and SCR of some corner reflectors installed in the area.
So far, I’ve calculated Sigma0 using radiometric calibration in S1TBX. However, when I tried to calculate Sigma0 in dB (using python) by the formula dB = 10*log10(Sigma0), I noticed the presence of NaN values in the results due to negative Sigma0 values being passed through log10.
Here sigma0 and his histogram, we can notice the presence of negative values on the histogram :
So when I convert sigma0 to dB I got the NaN values :
But when I export sigma0 directly from snap in dB the NaN values disappear and the the other values slightly change for non negative sigma0 :
Here is the difference between sigma0 in dB (converted in SNAP) and 10*log10(sigma0) converted outside SNAP :
Dose S1TBX calibration operator do something else than applying the formula when converting sigma0 to dB ?(For example replacing NaN values / filtering ?)
Does anyone know why this is happening ? Any help would be greatly appreciated.