Polarimetric calibration of airborne sar images using low helix scattering distributed targets

Polarimetric calibration (PolCal) of polarimetric synthetic aperture radar (PolSAR) images is essential for quantitative remote sensing applications. The distributed targets like forest, provide polarimetric constrains for PolCal, for example, reflection symmetry constrain. In this paper, we find that the helix scattering has a negative relationship with reflection symmetric distributed targets and is useful in PolCal. We first examined the tolerance of helix-ratio feature to polarimetric distortions, and then developed an algorithm to calibrate PolSAR images with this feature. Experiments with Chinese X-band airborne images show that PolCal with helix-ratio can improve the utilizing of distributed targets, and can improve the crosstalk accuracy.