Dear users and developers,
I have adapted the algorithm for Faraday Rotation Angle estimative presented in the ANNEX C of Calibration_palsar_products_v13.pdf (151.9 KB) for using with “band math” of SNAP.
OBS: It should be great if the developers should implement such algorithm within next updates.
The matrix M (2x2) represents the quad-pol data in circular basis:
M11_real = i_HH - q_VH - q_HV - i_VV
M11_imag = q_HH + i_VH + i_HV - q_VV
M12_real = - q_HH - i_VH + i_HV - q_VV
M12_imag = i_HH - q_VH + q_HV + i_VV
M21_real = - q_HH + i_VH - i_HV - q_VV
M21_imag = i_HH + q_VH - q_HV + i_VV
M22_real = - i_HH - q_VH - q_HV + i_VV
M22_imag = - q_HH + i_VH + i_HV + q_VV
The FR estimative for each pixel:
- FR_angle = 0.25 * atan ( ( -M12_realM21_imag + M12_imagM21_real) / (M12_realM21_real + M12_imagM21_imag) )
I will send the FR Angle Correction algorithm as soon as possible.
PS: It is supposed the Quad-Pol scattering matrix was already calibrated for channels x-talk and imbalance. The SNAP polarimetric calibration performs it, doensn’t?