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A Note on the SAR Polarimetry and Polarimetric Interferometry module
The proper utilisation of the processing functions, which are available within this module, requires a good knowledge of the Polarimetry and Polarimetric Interferometry principles and applications. Extensive information about these topics are provided by the ESA, Polarimetric SAR Interferometry tutorial.
The following functions are included in the Polarimetry section:
Polarimetric Calibration Matrix
It enables to obtain an accurate estimate of the target scattering matrix by using default or custom polarimetric calibration parameters.
Polarimetric Signature
It provides the real and theoretical estimate of the co-polarized and cross-polarized signatures of point-target-like objects (e.g. corner reflectors). The residual polarimetric calibration errors are also estimated.
Polarization Synthesis
Starting from a linearly-polarized dataset, it enables to create (i.e. synthesize) the scattering matrix for any arbitrary polarization orthogonal basis.
Polarimetric Decomposition
It provides coherent (i.e. Pauli decomposition) and incoherent (i.e. Entropy-Alpha-Anisotropy eigen-decomposition) methods for the scattering matrix decomposition. The first method is suitable for coherent local targets characterisation, while the second is intended for distributed target characterisation.
Polarimetric Classification
It consists of an unsupervised classification approach to discriminate different scattering behaviours on the basis of the Entropy Alpha Anisotropy decomposition result.
Polarimetric Features
It provides some possible combinations of co- and cross-polarized polarimetric Intensity data, which can be suitable for further interpretation or classification purposes.
The following functions are included in the Polarimetric Interferometry section:
SLC Coregistration
The polarimetric Reference and Secondary data sets are coregistered and over sampled in range direction.
Synthetic Phase Generation
The phase component, related to both the acquisition geometry (constant phase) and the flat Earth or the known topography (in case a Digital Elevation Model is used), is generated.
Coherence Optimisation
Interferograms and coherence data representative of the main scattering mechanisms are generated.
PPD / Interferogram Generation
Two types of products can be generated: i) the Polarimetric Phase Difference (PPD), which is generated from two different polarizations of the same acquisition; ii) the "classical" Interferogram, which is generated from the same polarization of two different coregistered acquisitions.
Synthetic Phase Flattening
The interferogram flattening can be executed using the synthetic phase generated from a different polarization of the same acquisition pair.
Polarimetric Coherence Generation
Coherence data relevant to the Polarimetric Phase Difference or to the single polarization interferogram are generated.
Note that:
–In case of SAR RAW products, the data must be imported and focussed (refer to Focusing module).
–Default setting for selected parameters can be specified in the Preferences panel.
–The SAR Tutorial, which includes basic knowledge on SAR theory and data processing, complements the online help.
–Co-ordinate decimal values must be entered using the dot (e.g. 29.30) and not the comma (e.g. 29,30) character.
References
ESA, Polarimetric SAR Interferometry tutorial