7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE1 High Resolution SAR Interferometry: estimation of local frequencies in the context of Alpine glaciers G. Vasile, E. Trouvé, I. Petillot, Ph. Bolon, J.-M. Nicolas, M. Gay, J. Chanussot, T. Landes and P. Grussenmeyer

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE2 Outlines Context: InSAR high resolution Local frequencies estimation algorithm Results and discussions Low Resolution ERS TANDEM data High Resolution simulated TS-X data Conclusions and perspectives

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE3 Low Resolution (LR) vs. High Resolution (HR) Longitudinal elevation profiles along the Mer-de-glace (m) LR – 80mLR+HR – 2m Mer-de-glace surface May 2004 Strong topography -> narrow fringes microreliefGlacier microrelief -> HR component Different surface penetration Different orientations

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE4 Need for frequencies estimates - Estimation Estimation of 2 nd order moments : complex correlation 3 directions for preserving the stationarity & ergodicity Spatial support: boxcar, directional, region growing… Appropriate estimator: ML, LLMMSE… Compensation of deterministic phase components STATIONARITY ERGODICITY Trade-off: ergodicity/stationarity – number of samples !

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE5 Need for frequencies estimates – 2D unwrapping Phase ambiguity Wrapped phase: φ = Φ (mod 2 π ) Nyquist criterion: | Φ (N) − Φ (M)| < π Phase difference test for unwrapping: Phase difference -> phase gradient -> local frequency

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE6 Outlines Context: InSAR high resolution Local frequency estimation algorithm Results and discussions Low Resolution ERS TANDEM data High Resolution simulated TS-X data Conclusions and perspectives

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE7 Phase LR+HR model Analytical phase signal: : 2D sine-wave estimated on large square windows ( * ) :2D sine-wave  Need of adaptive neighborhood  Need of new estimation technique (*) E. Trouvé et al. “Improving phase unwrapping techniques by the use of local frequency”, IEEE Transactions on Geoscience and Remote Sensing, 36(6): , 1998

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE8 Intensity Driven Adaptive Neighborhood (IDAN) (*) G. Vasile et al. “Intensity-Driven-Adaptive-Neighborhood Technique for Polarimetric and Interferometric SAR Parameters Estimation”. IEEE Transactions on Geoscience and Remote Sensing, 44(5): , step region growing technique ( * ) Driven simultaneously on all the intensities of the input data set; AN makes it possible to reach the number of pixels necessary for reliable estimation; most of the sources of phase nonstationarity are revealed by the SAR intensity which is mostly influenced by the local slope AN preserves the stationarity since most of the sources of phase nonstationarity are revealed by the SAR intensity which is mostly influenced by the local slope.

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE9 Estimation of the local frequency 2D phase model: Estimation technique based on the autocorrelation function: under stationarity and phase noise iid hypothesis  K real Step 1: estimation of on the N p,q available pixel pairs Step 2: estimation of the local frequency:

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE10 Algorithm implementation HR - IDAN FrequencyEstimation 2D - LR local frequencies SAR intensities LR MUSIC FrequencyEstimation SAR phase LR Freq. Compensation 2D - HR local frequencies Local compensation of LR deterministic geometrical phase component The resulting phase signal exhibits the local differences between the 2D sine-wave model and the real HR fringe pattern

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE11 Outlines Context: InSAR high resolution Local frequency estimation algorithm Results and discussions Low Resolution ERS TANDEM data High Resolution simulated TS-X data Conclusions and perspectives

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE12 TANDEM ERS data set master amplitude phase LR fringe orientation HR fringe orientation LUT Mer-de-glace glacier [C-band, 5-looks, 768x489 pixels, 20x20 m, e a =45m]

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE13 TANDEM ERS data set master amplitude phase LR+HR fringe orientation IDAN filtered phase LUT Mer-de-glace glacier [C-band, 5-looks, 768x489 pixels, 20x20 m, e a =45m]

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE14 TANDEM ERS data set LR+HR fringe orientation phase IDAN filtered coherence ROI-PAC filtered coherence LUT Mer-de-glace glacier [C-band, 5-looks, 768x489 pixels, 20x20 m, e a =45m]

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE15 TerraSAR-X application (a)(b) The Mer-de-glace glacier: (a) Aerotriangulation, (b) DTM 2mx2m.

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE16 TerraSAR-X application Slant range sampling of the SAR intensity Slant range sampling of the elevation (linear interpolation) Descending pass simulation 1.2x2m, α in =30, H=514km

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE17 TerraSAR-X application Simulated HR SAR amplitude: σ 2 =1 (speckle variance), 1.2x2m Real LR ERS SAR amplitude: 20x20m

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE18 TerraSAR-X application Simulated HR SAR amplitude: σ 2 =1 (speckle variance), 1.2x2m Simulated HR SAR phase: e a =10m, uniform phase noise distribution ±π/4

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE19 TerraSAR-X application Simulated HR SAR phase: e a =10m, uniform phase noise distribution ±π/4 LUT LR map: fringe orientation

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE20 TerraSAR-X application LR map: fringe orientation LUT LR+HR map: fringe orientation

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE21 TerraSAR-X application LR+HR map: fringe orientation IDAN LR+HR filtered phase LUT

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE22 TerraSAR-X application LUT May 2004 Photo of the simulated TerraSAR-X region on the Mer-de-glace glacier (approximate position of the profile) 50m spatial profile along the surface of the Mer-de-glace glacier: real altitude resampled in the TerraSAR-X slant range, unwrapped HR+LR estimates of the local frequencies, unwrapped LR estimates of the local frequencies.

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE23 Conclusions and perspectives Conclusions: HR frequency estimation combined with intensity driven adaptive neighborhood; HR frequency estimation combined with intensity driven adaptive neighborhood; estimate local frequencies within HR interferograms; estimate local frequencies within HR interferograms; measure the local topographic variations in interferograms with a small altitude of ambiguity. measure the local topographic variations in interferograms with a small altitude of ambiguity. Future directions:  Chamonix – Mont Blanc glacier monitoring by D-InSAR,  New context: POL-InSAR airborne data.

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE24 E-SAR Campaign Argentière: Oct./06 & Feb./07

7 th CNES/DLR Workshop LISTIC / TSI / GIPSA-lab / MAP-PAGE25 Thank you! This work was supported by the French national project ACI-MEGATOR. The authors wish to thank the European Space Agency for providing the SAR data through the Category 1 proposal No.3525.