Subsidence Monitoring Using Polarimetric Persistent Scatterers Interferometry Victor

Subsidence Monitoring Using Polarimetric Persistent Scatterers Interferometry Victor D. Navarro-Sanchez and Juan M. Lopez-Sanchez Signals, Systems and Telecommunications Group University of Alicante, Spain IGARSS’ 2011 24 -29 July, Vancouver, Canada

Overview • Introduction • PSI optimization • Polarimetric behaviour • Deformation results • Conclusions and future work IGARSS’ 2011 24 -29 July, Vancouver, Canada

Introduction Persistent Scatterers Interferometry (PSI) • Used extensively to measure surface deformation evolution • Exploits phase information of a stack of SAR differential interferograms • Selects for processing only good quality points (pixel candidates) • Different quality criteria: – Average coherence – Amplitude dispersion index – Others • Traditionally formulated and applied to single-pol data IGARSS’ 2011 24 -29 July, Vancouver, Canada

Introduction Concerning Polarimetry: • Sensitive to physical features of the scene (orientation, shape. . . ) • Widely used for physical parameter retrieval (forest height, biomass, soil moisture, etc. ) • Polarimetric interferometry (Pol. In. SAR) has a solid theoretical background Motivation: To find efficient ways to exploit polarimetric information in order to improve PSI performance: - Increase of the quality and number of pixel candidates - Extract additional information to classify scatterers IGARSS’ 2011 24 -29 July, Vancouver, Canada

PSI optimization General framework and formulation for vector interferometry [Cloude and Papathanassiou, 1998]: Scattering complex matrix (Sinclair Matrix): Target vector: Projection vector (normalized complex vector) Scattering coefficient (scalar complex) IGARSS’ 2011 24 -29 July, Vancouver, Canada

PSI optimization Formulation for vector interferometry adapted to the dual-pol case: Target vector: Projection vector parameterization: Navarro-Sanchez et al. , IEEE GRSL, 2010 IGARSS’ 2011 24 -29 July, Vancouver, Canada Search

PSI optimization Average coherence optimization: Average coherence: Scalar interferometry: Vector interferometry: Constraint: k IGARSS’ 2011 24 -29 July, Vancouver, Canada

PSI optimization Amplitude dispersion optimization: Amplitude dispersion: Amplitude standard deviation Average amplitude Scalar interferometry: Vector interferometry: Constraint: same i IGARSS’ 2011 24 -29 July, Vancouver, Canada

PSI optimization Data set 40 images of Murcia (Spain) Feb-09 to May-10 • Terra. SAR-X SLC data, stripmap mode • Dual-pol: HH and VV • Mean incidence angle: 37. 8 degrees • Resolution: 6. 6 m Az, 1. 17 m Rg • Pixel spacing: 2. 44 m Az, 0. 91 m Rg • Oversampling factors: 2. 7 Az, 1. 28 Rg All images have been provided by DLR under the framework of project GEO 0389 IGARSS’ 2011 24 -29 July, Vancouver, Canada

PSI optimization Histograms of and DA for conventional channels and computed optimum IGARSS’ 2011 24 -29 July, Vancouver, Canada

PSI optimization Average coherence criterion, ML 7 x 7, threshold 0. 7 VV Pixels selected = 24. 07% OPT Pixels selected = 38. 57% IGARSS’ 2011 24 -29 July, Vancouver, Canada

PSI optimization DA criterion, full-resolution, threshold 0. 3 VV Pixels selected = 6. 01% OPT Pixels selected = 16. 32% IGARSS’ 2011 24 -29 July, Vancouver, Canada

Polarimetric Behaviour Rural area Urban area IGARSS’ 2011 24 -29 July, Vancouver, Canada

Polarimetric Behaviour Average coherence criterion, ML 7 x 7, threshold 0. 7 Whole scene Urban Rural IGARSS’ 2011 24 -29 July, Vancouver, Canada Interpretation of figures for the Pauli basis

Polarimetric Behaviour DA criterion, full-resolution, threshold 0. 3 Whole scene Urban Rural IGARSS’ 2011 24 -29 July, Vancouver, Canada Interpretation of figures for the Pauli basis

Deformation results • ML 7 x 7 • 167 interferograms • 3 selection layers: γ > 0. 9 - 0. 8 - 0. 7 IGARSS’ 2011 24 -29 July, Vancouver, Canada

Deformation results OPT VV • New details are revealed • Results are consistent with ground truth data and with those presented in [Herrera et al. 2010] (single pol, ML 3 x 3) IGARSS’ 2011 24 -29 July, Vancouver, Canada

Summary • PSI can be enhanced by exploiting polarimetric information: – Average coherence: Improvement ≈ 60% more PCs selected – Amplitude dispersion: Improvement ≈ 170% more PCs selected • Polarimetric study of selected PSC: – Multi-look data: Dominance of dihedral-like scatterers – Single-look data: Dominance of anisotropic dihedrals and vertical structures • Retrieved deformation maps are denser and consistent with ground truth, proving the suitability of the approach • Future work: Study of selection criteria that make a more complete use of polarimetric information (i. e. polarimetric stationarity indicator) • Future work: Quad-pol extension IGARSS’ 2011 24 -29 July, Vancouver, Canada

Subsidence Monitoring Using Polarimetric Persistent Scatterers Interferometry Victor D. Navarro-Sanchez and Juan M. Lopez-Sanchez Signals, Systems and Telecommunications Group University of Alicante, Spain IGARSS’ 2011 24 -29 July, Vancouver, Canada