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Observing the Earth from the space.

A Satellite Radar Application

Álvaro MuñozSupervisor: Victor Hopman

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Introduction

• Background

– Land reclamation

– Soft unconsolidated soil

– Expected subsidence

– Need for monitoring

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Introduction

• Monitoring with Remote Sensing

– Sensors apart from objects

– Measurement--> Energy emitted/reflected

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Introduction• Remote Sensing Techniques

• Source of Energy

• Active/Pasive

• Electromagnetic Spectrum

• Optical/Thermal/Microwave

• Platform

• Manned-Unmanned Plane/Helicopter

• Kites

• Satellite

Active+Microwave+Satellite

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Remote Sensing with Satellite RADAR

• Radar Satellite Orbits

– Elliptical

– Near Polar

– Sun-Synchronous

– Height

• 500-1000 km

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• Active Sensor

– Measurement: Backscattering

Remote Sensing with Satellite RADAR

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• Polarization Dependent

– Example

• Horizontal+Vertical polarization

• Acquisition Geometry

– Azimuth (along track)

– Range (cross track)

Remote Sensing with Satellite RADAR

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• Synthetic Aperture Radar (SAR)

Remote Sensing with Satellite RADAR

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• Complex Waveform

– Parameter: Amplitude• Conventional SAR

• Complex Waveform

– Parameter: Phase• Interferometric SAR

(InSAR)

Remote Sensing with Satellite RADAR

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• Interferometric SAR

Remote Sensing with Satellite RADAR

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• Interferometric SAR

– Major limitation

• Temporal decorrelation

Remote Sensing with Satellite RADAR

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• Persistent Scatterer InSAR (PSInSAR)

Remote Sensing with Satellite RADAR

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• Persistent Scatterer InSAR (PSInSAR)

Remote Sensing with Satellite RADAR

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PSInSAR. Past Case Studies

• Deformation near the Wieliczka Salt Mine in Poland

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Salt Mine in Poland

• Subject and Motivations of the Study

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Salt Mine in Poland

• Available Data

• 51 images ERS-1/2 (ESA)

• 1992 to 2000

•Repeat cycle 34 days

• Single orbit direction

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Salt Mine in Poland• Experimental Results

– PS density

• Maximum=480 PS/km2 (center of Wieliczka)

• Minimum=30 PS/km2 (sparse urbanization areas)

• Average=92 PS/km2

– Comparison with subsidence maps � Agreement

• Leveling data 1970-2000

• PSInSAR data 1992-2000

– Field investigation

• Interpretation of Observations

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Salt Mine in Poland

• Experimental Results

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Salt Mine in Poland

• Conclusions

– Slow subsidence detected by PSInSAR

– Proof of utility of SAR archive

– Agreement leveling data

– More PS density --> Urban areas

– PS on landslide area

• Variability

• Horizontal displacement � limitation of PSInSAR

– Field inspection

• Confirmation of PSInSAR observations

• Hope for risk assessment

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PSInSAR. Recent Case Studies

• PSInSAR Analysis of damages during construction of parking near Koepoortbrug (Delft)

• Filter optimization for PSInSAR analysis

– Houtribdijk

• Monitoring Spoorzone Delft with PSInSAR

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• Subject and Motivations of the Study

Koepoortbrug

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• Available Data

Koepoortbrug

• Envisat (ESA)

• 2003 to 2006

•Every 35 days

• Single orbit direction

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• Experimental Results

Koepoortbrug

• Background: Amplitude SAR

• Overlaid: PS area of interest

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• Conclusions

– Historic data → normal behavior

– Envisat data not suitable. Reasons:

– Very sudden deformations

– Undersampling (35 day repetition rate)

– Possible change of orientation

• Temporal decorrelation

– Repair works

• Solution

– Another data set�

• Higher repetition rate

• Shorter wavelength (improve detectability)

Koepoortbrug

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PSInSAR. Recent Case Studies

• PSInSAR analysis of damages during construction of parking near Koepoortbrug (Delft)

• Filter optimization for PSInSAR analysis

– Houtribdijk

• Monitoring Spoorzone Delft with PSInSAR

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Houtribdijk

• Subject and Motivations of the Study

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• Available Data

Houtribdijk

• Envisat (ESA)

• 2003 to 2007

•Every 35 days

• Single orbit direction

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Houtribdijk

• Experimental Results

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Houtribdijk

• Conclusions

– Denoise filtering smooths time series

– Optimization: Triangular filter. Length 10-12 months

– Similar Performance: Gaussian filter > 12 months

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PSInSAR. Recent Case Studies

• PSInSAR analysis of damages during construction of parking near Koepoortbrug (Delft)

• Filter optimization for PSInSAR analysis

– Houtribdijk

• Monitoring Spoorzone Delft

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• Subject and Motivations of the Study

Spoorzone Delft

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• Available Data

Spoorzone Delft

38--- 40.5° 22.5--- 25.5°38--- 40.5° 22.5--- 25.5°38--- 40.5°38--- 40.5° 22.5--- 25.5°

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• Experimental Results

Spoorzone Delft

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Spoorzone Delft

• Experimental Results

IKEA parking:

• Soil subsidence

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• Experimental Results

– Correction of Geolocation (Reference: AHN&AHN2)

• Vertical offset (estimated height)

Spoorzone Delft

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• Experimental Results

– Correction of Geolocation (Reference: AHN&AHN2)

• Horizontal offset (estimated azimuth and range)

Spoorzone Delft

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• Experimental Results

– Correction of Geolocation (Reference: AHN&AHN2)

• Cross Sections

Spoorzone Delft

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• Experimental Results

– Combination of Ascending/Descending Orbits

Spoorzone Delft

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• Experimental Results

– Combination of Ascending/Descending Orbits

Spoorzone Delft

ASCENDING ORBIT

DESCENDING ORBIT

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• Experimental Results

– Thermal Expansion

Spoorzone Delft

Power of the technique:

• Detect thermal expansion in high buildings

Correlation:

• PSInSAR�thermal theory

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Spoorzone Delft

• Experimental Results

– Thermal Expansion

Vermeer Toren:

• 7,3mm vertical deformation

• (Thermal expansion)

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• Experimental Results

– Detectable Deformation

Spoorzone Delft

Side tilt1 mm

Subsidence1.09 mm

Front tilt7.7 mm

Side tilt1 mm

Subsidence1.09 mm

Front tilt7.7 mm

Side tilt1 mm

Subsidence1.09 mm

Front tilt7.7 mm

Side tilt1 mm

Subsidence1.09 mm

Front tilt7.7 mm

Side tilt1 mm

Subsidence1.09 mm

Front tilt7.7 mm

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Conclusions

• Power – Historic archive (past/future)

– Large coverage

– Cost

– Processing improvements

• Interpretation of observations not straightforward

• PS → physical entities?

PSInSAR can provide mm accuracy in detection of deformation

Monitoring Structures → Damage prevention