a subsidence monitoring project using a polarimetric gb-sar...

Electromagnetic Engineering & Photonics Group Signal Theory and Communications

A Subsidence Monitoring Project using a Polarimetric A Subsidence Monitoring Project using a Polarimetric GBGB--SAR SensorSAR Sensor

Universitat PolitUniversitat Politèècnica de Catalunya (UPC)cnica de Catalunya (UPC)

Dept. de Teoria del Senyal i Comunicacions, Barcelona, Dept. de Teoria del Senyal i Comunicacions, Barcelona, SpainSpain

PolInSAR – 22-26 January 2007 ESA-ESRIN Frascati (Italy)

Luca Pipia, Xavier Fabregas, Albert Aguasca, Carlos LopezLuca Pipia, Xavier Fabregas, Albert Aguasca, Carlos Lopez--Martinez, Martinez, Jordi. Jordi. J. J. MallorquiMallorqui, Oscar Mora(1), Oscar Mora(1)

(1)(1)InstitutInstitut CartogrCartogrààficfic de de CatalunyaCatalunya (ICC)(ICC)

ParcParc de de MontjuicMontjuic, 08036, Barcelona, Spain, 08036, Barcelona, Spain

UPC3

UPC3 UPC, 28/11/2004


ContentsContents

Introduction

Test-Site Description

Measuring Campaign Organization

PolSAR Data Acquisition and Calibration

Polarimetric Urban Environment Analysis

Daily and Extended Temporal Analysis

Coherence VS Amplitude Approach: First Results

Urban Targets Instability

Summary and Conclusions


TestTest--Site DescriptionSite Description

Sallent Village

Estació District


TestTest--Site DescriptionSite Description

On-Going Subsidence Phenomenon: Deformation Speed (2cm/year)

Multiple set of techniques:topographic leveling, geological mapping, geophysic prospection, extensometric measurements, drilling


UPC GB-SAR Position

Nº : 41 49 4.8

Eº : 1 54 8.9

H : 361 (m)


UPC Ground-Based SAR Sensor

2.5m

RF-Block+ Deramping

Signal Generation Unit +PC with

Sampling Card

Observation Geometry

POL-InSAR Antennas (Bistatic Configuration)

POL-SAR Antennas

80 cm

TX RX

RXDDS Chipset-Based


Mine’sTransport Belt

Ground-step Profile

Buildings

Sallent: Imagen Span


Hill Slope


PolSAR Data Acquisition and CalibrationPolSAR Data Acquisition and Calibration

Measurement Campaign:

Zero-baseline PolSAR Data acquired every 20 minutes for at least 7 hours

Polarimetric Calibration: [ ] hh hv hh hv hh hv

vh vv vh vv vh vv

R R S S T TM N

R R S S T T⎡ ⎤ ⎡ ⎤ ⎡ ⎤

= +⎢ ⎥ ⎢ ⎥ ⎢ ⎥⎣ ⎦ ⎣ ⎦ ⎣ ⎦

Corner Reflector Response: Polarization Purity 30dB GB-System with a Diagonal Distortion Matrix

Time for Polarimetric Scanning: 2min:20 sec (2m - 200 points- 128 Time AVG)


PolSAR Data Acquisition and CalibrationPolSAR Data Acquisition and Calibration

Polarimetric Calibration:GB-System with a

Diagonal Distortion Matrix

2hh hh

hv hv

vh vh

vv vv

M Y k SM YkSM Y kSM YS

α

α

=

==

=[ ] hh

vv vvvv

RYk R T

R⎡ ⎤

= ⎢ ⎥⎣ ⎦

vv hh

vv hh

R TT R

α =1 Pure Co-Polar Target (Corner Reflector)

1 Pure Cross-Polar Target (45ºBruderhedral)(Ulaby, Elachi 1990)

55 cm65 cm

Cylinder Curvature Radius : 2.5m

Bruderhedral Dimensions

GBSAR Real Data

GRECO Simulator

45 cm[ ] 0 1

1 0BrudS k

⎡ ⎤= ⎢ ⎥

⎣ ⎦

19dB


Polarimetric Urban Environment AnalysisPolarimetric Urban Environment Analysis

Pauli’s Decomposition: RGB Images

Simple Weighted by span

Trihedral-Like or Odd Bounce

Dihedral-Like or Even Bounce

45º Dihedral-Like or Volume

Scattering Mechanism


Daily and Extended Temporal AnalysisDaily and Extended Temporal Analysis

Sequence of PolSAR Data

First 10 measures discarded for devices heating

Al least 20 useful datasets for each day of measure

Day1_Sallnt01

Day1_Sallnt02

Day1_Sallnt03

…

Day1_SallntN1

ATM Compensation (M1) (1)

Day1ATMComp_Sallnt01



…

Day1ATMComp_SallntN1

Day1ATMComp_PolCalSallnt01



…

Day1ATMComp_PolCalSallntN1

Polarimetric CAL

Averaged-Day

(1) L.Pipia et Al., “Atmospheric Artifact Estimation and Compensation in Differential Polarimetric GB-SAR Acquisitions”, EUSAR06, Dresden, Germany

Example (Time delay 4 hours):10am-2pm

Cross-Range(m)

[ ]iSΣAdditive Noise Reduction

time

Hyp – No Subsidence effects


[ ]iS

Daily and Extended Temporal AnalysisDaily and Extended Temporal Analysis

Averaged Day-1

[ ]iSΣ ATM Compensation (DAY1-DAY2,3…)Averaged Day- 2

[ ]iSΣ

Master

Averaged Day- 3

[ ]iSΣAveraged Day- 4

[ ]iSΣ[ ]iSΣAveraged Day- N

[ ]iSΣAtmospheric Conditions are referred to the master DATASET

17:009:00

17:308:30

11:3017:30

9:0015:00

10:2016:30

7:0013:00

11:0018:00

18-9/1228-9/1114/1120/1019/0926/0729/06MEASUREMENT DAYS

Collection of Calibrated Zero-Baseline Polarimetric Dataset

DATASETNi ...1=


HH Polarization June-July

Coherence VS Amplitude Approach: First ResultsCoherence VS Amplitude Approach: First Results

Coherence-Based Analysis Amplitude-Based AnalysisDifferential Phase

7x7 Box Car (Pixels size: 1.5x1.5 m2) SLC (Pixels size: 1.5x1.5 m2)

Amplitude Mask based Stability


HH Polarization June-September


Coherence-Based Analysis Amplitude-Based AnalysisDifferential PhaseAmplitude Mask based Stability



HH Polarization June-November





HH Polarization June-December






Linear Deformation Speed can be retrieved

The estimation error reduced by merging polarimetric information

4vert

Rrh

π φλ

⎛ ⎞∆ = ∆⎜ ⎟⎝ ⎠

Polarimetric Differential Displacement Retrieval(Coherent Approach)

Advanced Differential Technique can be now applied (CPT)


Urban Targets InstabilityUrban Targets Instability

How to merge the Differential Polarimetric Information?

Nocturnal Monitor Activity

What criterion to Weight each polarization Channel?

What Polarization must be trusted?

Very high jumps (Amplitude and Phase)

Data acquired from 6pm of Dec.18th to 9am on Dec.19th.Fixed Corner Reflector (600m)

Polarimetric ResponseNo System Failure Occurred!!!

Data acquired from 9am to 3pm on October 20th

Diurnal Monitoring Activity



DAY1 DAY2 DAY3 DAY4 DAY5 DAY6 DAY7

Fixed Trihedral : Temporal Profile of Pauli’s Components

17:009:00

17:308:30

11:3017:30

9:0015:00

10:2016:30

7:0013:00

11:0018:00

PolSAR Cross-Range Profile

Pauli’s RGB Image



DAY1

DAY2

DAY3

DAY4

DAY5

DAY6

DAY7

TARGET 1

TARGET 2

Pauli’s RGB weighted by SpanWhat Polarimetric information must be trusted?

17:009:00

17:308:30

11:3017:30

9:0015:00

10:2016:30

7:0013:00

11:0018:00


Summary and ConclusionsSummary and ConclusionsA Subsidence Monitoring Project using an X-Band PolInSAR Ground-Based Sensor has been presented

using a PolSAR Data Temporal Series

The polarimetric description of the district under observation using the Pauli’s Decomposition revealed that at X-Band in the GBSAR acquisition geometry the cross-polar contribution is not essential .

First results using a single-polarization approach for the three polarimetric channels (HH, HV, VV) have been shown. A processing scheme for daily and extended temporal analysis that takes into account the atmospheric artefact effects has been proposed.

Quantitative results about the subsidence phenomenon can be improved using a more sophisticated approach. A stability criterion for pixels selection must be applied. The combined analysis of the co-polar channels turns out to be useful for increasing the number of the reliable pixels.

The polarimetric signature of urban target at X-Band revealed being extremely variable in time. Measurements performed at different moment of the day showed fluctuations in the polarimetric response of the target related to the dynamic structure that a urban environmental assumes during the 24hours. The night turned out to be the best moment to acquire X-Band data, both for atmosphere and for targets’ stability.

The problem of urban target fluctuations during a whole day at X-Band is surely increased by the acquisition geometry of Ground-based SAR sensor. Nevertheless, the wavelength is supposed to play a key-role due to its sensitivity to the geometrical properties of deterministic targets.

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