Effect of medium symmetries in limiting the number of parameters estimated with polarimetric interferometry

The addition of interferometric backscattering pairs to the conventional polarimetric SAR data over forests and other vegetated areas increases the dimensionality of the data space, in principle enabling the estimation of a larger number of parameters. The effect of medium symmetries on the number of independent interferometric measurements is studied. Reflection, rotation, and azimuthal symmetries are considered. In each case, the number of independent elements of the interferometric covariance matrix is derived, which puts an inherent limit on the number of scatterer parameters that can be estimated using single-baseline polarimetric interferometry