High Resolution SAR Interferometry: estimation of local
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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 [email protected] Outlines. Context: InSAR high resolution

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G. Vasile , E. Trouvé, I. Petillot, Ph. Bolon, J.-M. Nicolas,

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G vasile e trouv i petillot ph bolon j m nicolas

High Resolution SAR Interferometry: estimation of localfrequencies 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

[email protected]

LISTIC / TSI / GIPSA-lab / MAP-PAGE


Outlines

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

LISTIC / TSI / GIPSA-lab / MAP-PAGE


Low resolution lr vs high resolution hr

Low Resolution (LR) vs. High Resolution (HR)

LR – 80m

LR+HR – 2m

Mer-de-glace surface May 2004

Longitudinal elevation profiles along the Mer-de-glace (m)

  • Strong topography -> narrow fringes

  • Glacier microrelief -> HR component

    • Different surface penetration

    • Different orientations

LISTIC / TSI / GIPSA-lab / MAP-PAGE


Need for frequencies estimates estimation

STATIONARITY

ERGODICITY

Need for frequencies estimates - Estimation

  • Estimation of 2nd 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

Trade-off: ergodicity/stationarity – number of samples !

LISTIC / TSI / GIPSA-lab / MAP-PAGE


Need for frequencies estimates 2d unwrapping

Need for frequencies estimates – 2D unwrapping

Phase ambiguity

  • Wrapped phase: φ = Φ (mod 2π)

  • Nyquist criterion: | Φ(N) − Φ(M)| < π

  • Phase difference test for unwrapping:

Phase difference -> phase gradient -> local frequency

LISTIC / TSI / GIPSA-lab / MAP-PAGE


Outlines1

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

LISTIC / TSI / GIPSA-lab / MAP-PAGE


Phase lr hr model

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):1963-1972, 1998

LISTIC / TSI / GIPSA-lab / MAP-PAGE


Intensity driven adaptive neighborhood idan

Intensity Driven Adaptive Neighborhood (IDAN)

  • 2-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;

  • AN preserves the stationarity since most of the sources of phase nonstationarityare revealed by the SAR intensity which is mostly influenced by the local slope.

(*) 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):1609-1621, 2006

LISTIC / TSI / GIPSA-lab / MAP-PAGE


Estimation of the local frequency

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 Np,q available pixel pairs

  • Step 2: estimation of the local frequency:

LISTIC / TSI / GIPSA-lab / MAP-PAGE


Algorithm implementation

2D - LR

local frequencies

SAR intensities

LR MUSIC

Frequency

Estimation

LR Freq.

Compensation

2D - HR

local frequencies

HR - IDAN

Frequency

Estimation

SAR phase

Algorithm implementation

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

LISTIC / TSI / GIPSA-lab / MAP-PAGE


Outlines2

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

LISTIC / TSI / GIPSA-lab / MAP-PAGE


Tandem ers data set

TANDEM ERS data set

LUT

masteramplitude

phase

LR fringe orientation

HR fringe orientation

Mer-de-glace glacier [C-band, 5-looks, 768x489 pixels, 20x20 m, ea=45m]

LISTIC / TSI / GIPSA-lab / MAP-PAGE


Tandem ers data set1

TANDEM ERS data set

LUT

masteramplitude

phase

IDANfiltered phase

LR+HR fringe orientation

Mer-de-glace glacier [C-band, 5-looks, 768x489 pixels, 20x20 m, ea=45m]

LISTIC / TSI / GIPSA-lab / MAP-PAGE


Tandem ers data set2

TANDEM ERS data set

LUT

LR+HRfringe orientation

phase

ROI-PACfiltered coherence

IDAN filtered coherence

Mer-de-glace glacier [C-band, 5-looks, 768x489 pixels, 20x20 m, ea=45m]

LISTIC / TSI / GIPSA-lab / MAP-PAGE


Terrasar x application

TerraSAR-X application

(a)

(b)

The Mer-de-glace glacier: (a) Aerotriangulation, (b) DTM 2mx2m.

LISTIC / TSI / GIPSA-lab / MAP-PAGE


Terrasar x application1

TerraSAR-X application

Descending pass simulation

1.2x2m, αin=30, H=514km

Slant range sampling of the SAR intensity

Slant range sampling of the elevation (linear interpolation)

LISTIC / TSI / GIPSA-lab / MAP-PAGE


Terrasar x application2

TerraSAR-X application

Simulated HR SAR amplitude: σ2=1 (speckle variance), 1.2x2m

Real LR ERS SAR amplitude: 20x20m

LISTIC / TSI / GIPSA-lab / MAP-PAGE


Terrasar x application3

TerraSAR-X application

Simulated HR SAR amplitude: σ2=1 (speckle variance), 1.2x2m

Simulated HR SAR phase: ea=10m, uniform phase noise distribution ±π/4

LISTIC / TSI / GIPSA-lab / MAP-PAGE


Terrasar x application4

TerraSAR-X application

LUT

LR map:fringe orientation

Simulated HR SAR phase: ea=10m, uniform phase noise distribution ±π/4

LISTIC / TSI / GIPSA-lab / MAP-PAGE


Terrasar x application5

TerraSAR-X application

LUT

LR map:fringe orientation

LR+HR map:fringe orientation

LISTIC / TSI / GIPSA-lab / MAP-PAGE


Terrasar x application6

TerraSAR-X application

LUT

LR+HR map:fringe orientation

IDAN LR+HR filtered phase

LISTIC / TSI / GIPSA-lab / MAP-PAGE


Terrasar x application7

TerraSAR-X application

LUT

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.

May 2004Photo of the simulated TerraSAR-X region on the Mer-de-glace glacier (approximate position of the profile)

LISTIC / TSI / GIPSA-lab / MAP-PAGE


Conclusions and perspectives

Conclusions and perspectives

Conclusions:

  • HR frequency estimation combined with intensity driven adaptive neighborhood;

  • estimate local frequencies within HR interferograms;

  • 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.

LISTIC / TSI / GIPSA-lab / MAP-PAGE


E sar campaign

E-SAR Campaign

Argentière: Oct./06 & Feb./07

LISTIC / TSI / GIPSA-lab / MAP-PAGE


G vasile e trouv i petillot ph bolon j m nicolas

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.

LISTIC / TSI / GIPSA-lab / MAP-PAGE


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