Statistics for complex correlation coefficients applied to advanced SAR modes: Interferometry and polarimetry

For applications such as change monitoring, classification or building detection, advanced SAR modes can provide useful additional information. The comparison of two different images trough Interferometry or Polarimetry is often done using complex correlation. Degree of coherence γ is considered as an indicator of the accuracy of the interferometric fringes or the polarimetric phase. Since multiple parameters are involved in the SAR measurement and the empirical correlation, this assumption is to be qualified. The purpose of this paper is to investigate the link between the degree of coherence and the statistics of the phase particularly in low signal to noise ratio environment. We present tools based on the directional statistics as an alternative way to describe the phase and we compare their behaviour with the classical γ.