Target Characterization and Scattering Power Decomposition for Full and
Compact Polarimetric SAR Data
Abstract
This manuscript was accepted for publication on IEEE Transactions on
Geoscience and Remote Sensing.
Abstract: In radar
polarimetry, incoherent target decomposition
techniques help extract scattering information from polarimetric
SAR data. This is achieved either by fitting appropriate scattering
models or by optimizing the received wave intensity
through the diagonalization of the coherency (or covariance)
matrix. As such, the received wave information depends on
the received antenna configuration. Additionally, a polarimetric
descriptor that is independent of the received antenna configuration
might provide additional information which is missed by the individual
elements of the coherency matrix. This implies that existing target
characterization techniques might neglect this information. In this
regard, we suitably utilize the 2D and 3D Barakat degree of polarization
which is independent of the received antenna configuration to obtain
distinct polarimetric information for target characterization. In this
study, we introduce new roll-invariant scattering-type parameters for
both full-polarimetric (FP) and compact-polarimetric (CP) SAR data.
These new parameters jointly use the information of the 2D and 3D
Barakat degree of polarization and the elements of the coherency (or
covariance) matrix. We use these new scattering type parameters, which
provide equivalent information as the Cloude alpha for FP SAR data and
the ellipticity parameter chi for CP SAR data, to characterize various
targets adequately. Additionally, we appropriately utilize these new
scattering-type parameters to obtain unique non-model based
three-component scattering power decomposition techniques. We obtain the
even-bounce, and the odd-bounce scattering powers by modulating the
total polarized power by a proper geometrical factor derived using the
new scattering-type parameters for FP and CP SAR data. The diffused
scattering power is obtained as the depolarized fraction of the total
power. Moreover, due to the nature of its formulation, the decomposition
scattering powers are nonnegative and roll-invariant while the total
power is conserved. The proposed method is both qualitatively and
quantitatively assessed utilizing the L-band ALOS-2 and C-band
Radarsat-2 FP and the associated simulated CP SAR data.