1. 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

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

3. 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

4. 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 (PolInSAR) 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

5. 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): Projection: Target vector: Scattering coefficient (scalar complex)‏ Projection vector (normalized complex vector)‏

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

7. IGARSS’2011 24-29 July, Vancouver, Canada Average coherence optimization: Average coherence: Scalar interferometry: Vector interferometry: Constraint:      k PSI optimization

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

9. IGARSS’2011 24-29 July, Vancouver, Canada Data set 40 images of Murcia (Spain) Feb-09 to May-10 TerraSAR-X SLC data, stripmap mode Dual-pol: HH and VV Mean incidence angle: 37.8 degrees Resolution: 6.6m Az, 1.17m Rg Pixel spacing: 2.44m Az, 0.91m Rg Oversampling factors: 2.7 Az, 1.28 Rg All images have been provided by DLR under the framework of project GEO0389 PSI optimization

10. IGARSS’2011 24-29 July, Vancouver, Canada Histograms of  and D A for conventional channels and computed optimum PSI optimization

11. IGARSS’2011 24-29 July, Vancouver, Canada Average coherence criterion, ML 7x7, threshold 0.7 VV Pixels selected = 24.07% OPT Pixels selected = 38.57% PSI optimization

12. IGARSS’2011 24-29 July, Vancouver, Canada D A criterion, full-resolution, threshold 0.3 VV Pixels selected = 6.01% OPT Pixels selected = 16.32% PSI optimization

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

14. IGARSS’2011 24-29 July, Vancouver, Canada Polarimetric Behaviour Average coherence criterion, ML 7x7, threshold 0.7 Interpretation of figures for the Pauli basis Whole sceneUrbanRural

15. IGARSS’2011 24-29 July, Vancouver, Canada Polarimetric Behaviour D A criterion, full-resolution, threshold 0.3 Interpretation of figures for the Pauli basis Whole sceneUrbanRural

16. IGARSS’2011 24-29 July, Vancouver, Canada Deformation results ML 7x7 167 interferograms 3 selection layers: γ > 0.9 - 0.8 - 0.7

17. IGARSS’2011 24-29 July, Vancouver, Canada Deformation results VV OPT New details are revealed Results are consistent with ground truth data and with those presented in [Herrera et al. 2010] (single pol, ML 3x3)

18. 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

19. 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