Dual versus Quadpol: a New Test Statistic for Radar Polarimetry

In this paper we develop a new statistical test to determine whether quad or dual (including compact) polarisation modes are best for use in low frequency SAR applications. We first consider a general formulation of dual/compact modes and use it to expose a fundamental weakness in compact reconstruction algorithms. We then show how all dualpol scattering problems can effectively be localised geometrically in the entropy/alpha plane. By defining a differential alpha parameter we can then establish a test statistic for determining which mode is best. We apply this test to various data sets from the ALOS-PALSAR sensor.