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Validation and quality control for InSAR using trihedral radar - - PowerPoint PPT Presentation

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Validation and quality control for InSAR using trihedral radar reflectors Delft University of Technology Petar Marinkovic, Gini Ketelaar, Freek van Leijen, Ramon Hanssen DEOS: Delft Institute of Earth Observation and Space Systems January 16,

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January 16, 2008

Delft University of Technology

DEOS: Delft Institute of Earth Observation and Space Systems

Validation and quality control for InSAR using trihedral radar reflectors

Petar Marinkovic, Gini Ketelaar, Freek van Leijen, Ramon Hanssen

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Delft test site: impressions

January 2004 leveling

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Agenda

Objective and motivation:

  • what is the quality of point scatterer phase
  • bservation in PSI?

Delft test site:

  • corner reflector experiment
  • defo. monitoring under controlled circumstances

Validation strategy and results:

  • leveling vs. InsAR vs. PSI

Conclusions

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Leveling vs. InSAR

CR4-CR3 CR4-CR5 ASAR ERS Leveling

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Leveling vs. InSAR: a posteriori 1sigma

CR4-CR3 CR4-CR5 ASAR ERS Leveling

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Leveling vs. InSAR: a posteriori 1sigma

CR4-CR3 CR4-CR5 ASAR ERS Leveling

1Sigma_ASAR= 1.6 mm 1Sigma_ERS2 = 2.8 mm

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Delft test site

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Delft test site: leveling network

CR#5 CR#4 CR#3 Bn#2 Bn#1

  • surveys every ~35 days
  • high precision leveling
  • redundant network
  • adjustment and outlier removal
  • since Aug.2005 ground water

measurements ~200m

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Delft test site: CR heights

ground watter measurements correlate with leveling ~95%

CR3 CR4 CR5

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Delft test site: InSAR data [ASAR]

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Delft test site: InSAR data [ERS2]

ERS2: high fDC!

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Delft test site

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Validation strategy: Leveling vs. InSAR

Leveling estimates:

  • redundant network/measurements
  • adjustment and testing
  • a.posteriori 1sigma of dd ~ 1.5mm
  • “mature” technique

InSAR estimates:

  • unwrapped wrt. leveling
  • converted to vertical
  • full VC matrix
  • “connection matrix”
  • SCR (signal to clutter)

“fixed”

Mathematical framework:

  • analysis of residuals (leveling – InSAR)
  • constrained adjustment
  • outlier removal
  • VCE (variance component estimation)

Analysis output:

  • 1sigma of InSAR.dd

deformation measurements

  • a.posteriori “error bars”
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Leveling vs. InSAR: “raw”

CR4-CR3 CR4-CR5

1Sigma_ASAR= 2.4 mm 1Sigma_ERS2 = 10.7 mm

ASAR ERS Leveling

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Doppler variations of ERS2

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ground range azimuth

Influence of viewing geometry

...compensates for unaccounted reference phase

actual location of point target reference of interferometric phase computation reference of “flat-earth phase”

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ground range azimuth

Influence of viewing geometry

...compensates for unaccounted reference phase

sub.pixel correction:

  • azimuth: delta fDC dependence
  • range: Bperp dependence

actual location of point target reference of interferometric phase computation reference of “flat-earth phase”

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Doppler variations of ERS2

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Leveling vs. InSAR: “raw”

CR4-CR3 CR4-CR5

1Sigma_ASAR= 2.4 mm 1Sigma_ERS2 = 10.7 mm

ASAR ERS Leveling

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Leveling vs. InSAR: sub.pixel corrected

CR4-CR3 CR4-CR5

1Sigma_ASAR= 1.7 mm 1Sigma_ERS2 = 6.9 mm

ASAR ERS Leveling

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Doppler ambiguities?

+2*PRF

  • 2*PRF

CR3-CR4: difference InSAR vs levelling Doppler centroid

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Leveling vs. InSAR: sub.pixel corrected

CR4-CR3 CR4-CR5 ASAR ERS Leveling

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Leveling vs. InSAR: sub.pixel.no.outliers.doppler

CR4-CR3 CR4-CR5

1Sigma_ASAR= 1.6 mm 1Sigma_ERS2 = 2.8 mm

ASAR ERS Leveling

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a.posteriori 1sigma of dd InSAR phase

no sub-pixel correction with sub-pixel correction with sub-pixel and fDC correction ERS2 ASAR 4.5 mm 2.9 2.8 1.6 1.6 2.4

  • with outlier removal -

no sub-pixel correction with sub-pixel correction with sub-pixel and fDC correction ERS2 ASAR 10.7 6.9 4.1 1.7 1.7 2.4

  • without outlier removal -
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Leveling vs. InSAR: a posteriori 1sigma

CR4-CR3 CR4-CR5 ASAR ERS Leveling

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Connection to the natural PS

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Connection to natural PS

  • linear velocities estimated together with periodic signal
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CR3 CR4 CR5

ground watter measurements

Natural PS vs Leveling

PSI Leveling

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Natural PS vs Levelling vs InSAR

CR4-CR3 CR4-CR5 ASAR PSI Leveling

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Conclusions

  • empirical 1sigma of InSAR deformation estimates:
  • ERS2 (high.doppler.data): ~ 2.8 mm along the vertical
  • ASAR: ~ 1.6 mm along the vertical
  • Note: ASAR in the same level of accuracy as leveling!