Radar Remote Sensing (SAR Interferometry, Techniques and Applications)

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Radar Remote Sensing (SAR Interferometry,
Techniques and Applications)By Falah Fakhri
Post-doctoral Scholar falah.fakhri_at_utu.fi
https//www.researchgate.net/profile/Falah_Fakhri
https//falahfakhri.wordpress.com
https//twitter.com/FALAHFAKHRI? Department of
Geography and Geology

Friday 06/06/2014 Time 1415 1445
MAANTIETEEN JA GEOLOGIAN LAITOS
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• Overview
• Concept of Radar and SAR
• SAR Image Format and Characteristics
• Amplitude
• Phase
• SAR Interferometry (InSAR)
• Coherence
• Interferogram
• Techniques of SAR Interferometry
• Conventional SAR Interferometry (Differential SAR
  interferometry)
• Stacking SAR Interferometry
• Persistent Scatterers Interferometry (PSI) or
  Interferometric Permanent Target Analysis (IPTA)
• Small Baseline Subset Technique (SBAS)
• Software's are used in SAR Interferometry
• Present and Future plans and strategy

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Concept of Radar and SAR (1/8)

• Imagine you are in the Grand Valley and you
  shout. The cliffs will reflect the sound wave.
  After some time you will hear an echo, which is
  not exactly the same compared to what you
  shouted. This is the principle of a radar!

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Concept of Radar and SAR (2/8)

• RADAR stands for Radio Detection and Ranging so
  what is a Radar?
• A (Imaging) Radar is an active system that uses
  a transmitter to illuminate a scene. The pulses
  sent are microwaves, i.e. a wave with an
  amplitude and a phase, having a certain frequency
  and polarization.
• The radar then records the echo
• scattered back from the objects/targets
• B Non imaging

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• Concept of Radar and SAR (3/8)

MAANTIETEEN JA GEOLOGIAN LAITOS
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• Concept of Radar and SAR (4/8)
• radars illuminate the target
• so that they
• can operate day and night.
• Microwave frequencies
• Electromagnetic
• waves penetrate to
• Some extent through media.
• At most frequencies clouds are
• transparent!
• Complex interaction with medium or
• target
• a Radar image is not a photo!

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Concept of Radar and SAR (5/8)
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Concept of Radar and SAR (6/8)

• Surface Roughness
• Back-scattering increases with roughness
• Moisture content
• Back-scattering
• increases with moisture
• Topography
• Viewing geometry
• affects the signal

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Concept of Radar and SAR (7/8)
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Concept of Radar and SAR (8/8)

• Synthetic Aperture Radar (SAR)
• It has cloud-penetrating capabilities
• because it uses imaging system.
• It has day and night operational
• capabilities because it is an active system.
• Finally, its interferometric configuration

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SAR Image Format and Characteristics (1/5)
Raw data
Detected SAR image, Single Look Complex, (SLC)
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SAR Image Format and Characteristics (2/5)

• Amplitude
• The detected SAR image contains
• a measurement of the Amplitude
• (Intensity) of the radiation
• backscattered toward the radar by
• the objects (scatterers) contained in each SAR
  resolution
• cell.
• Typically, exposed rocks and urban areas show
  strong
• amplitude ( bright pixel) whereas smooth flat
  surface, like quiet water basins show low
  amplitude (dark pixels) since the
• Backscatters (radiation) is mainly measured away
  from the radar.

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SAR Image Format and Characteristics (3/5)

• Phase
• The pulses (radiation) transmitted
• from the radar has to reach the
• scatterers on the ground and then
• to comeback to the radar in order
• to form the SAR image.
• Scatterers at different distance from the radar
  introduce a different delay between transmission
  and reception of the radiation.

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SAR Image Format and Characteristics (4/5)

• Ascending

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SAR Image Format and Characteristics (5/5)

• Descending

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SAR Interferometry (InSAR)(1/13)

• Interferometry,
• Compared with conventional
• geodetic techniques, one
• capability long remained out of
• reach for radar The measurement
• of angles. Similar to a single
• human eye, which is essentially
• blind for the difference in distance to
  objects, it is impossible for radar or SAR to
  distinguish two objects at the same range - but
  different angles- to the instrument. (Hanssen,
  2001)

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SAR Interferometry (InSAR)(2/13)

• SAR interferometry (InSAR)
• Interferometric Synthetic
• Aperture Radar (InSAR),
• also referred to as SAR
• Interferometry consists of
• Interfering two SAR images
• of an area, which have been
• acquired from two slightly
• different positions in space or time.

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• SAR Interferometry (InSAR) (3/13)
• phase is called the interferometric phase.
• InSAR phase measures the phase difference of a
  target with respect to the radar. The
  interferometric phase image has values between 0
  and 2? (or between -? and ? depending on the
  representation used) and therefore appears as a
  series of fringes.

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SAR Interferometry (InSAR)(4/13)

• phase
• Displacement
• phase
• Topography

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SAR Interferometry (InSAR) (5/13)

• phase (example)
• two images being interfered. It is possible to
  measure the signal phase change, or interference,
  over time.

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SAR Interferometry (InSAR) (6/13)

• phase (example)

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SAR Interferometry (InSAR) (7/13)

• Coherence
• The coherence measures the degree of correlation
  between the two SAR images. It is a normalized
  quantity with values between 0 and 1.
• interferogram
• The product of SAR interferometry is called the,
  a complex image obtained from the
  cross-correlation of two overlapping complex SAR
  images.

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SAR Interferometry (InSAR) (8/13)
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SAR Interferometry (InSAR) (9/13)

• Master image 19960228 Slave
  image 19960403

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SAR Interferometry (InSAR) (10/13)

• Coherence 19960228-19960403

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SAR Interferometry (InSAR) (11/13)

• Interferogram (Deformation) 19960228-19960403

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SAR Interferometry (InSAR) (12/13)

• Spaceborne SAR interferometric systems

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SAR Interferometry (InSAR) (13/13)Satellite
Radar Systems available now and into the future
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Techniques of SAR Interferometry (1/6)

• Conventional SAR Interferometry (Repeated pass
  Interferometry )
• In repeat-pass InSAR, two or more SAR images are
  acquired at different times with the same or a
  corresponding sensor from almost identical aspect
  angles.

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Techniques of SAR Interferometry (2/6)

• Master image 18 February 1996 Slave image 28
  April 1996

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Techniques of SAR Interferometry (3/6)
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Techniques of SAR Interferometry (4/6)

• Stacking SAR Interferometry (Interferometric
  Stacking) The basic idea of interferogram
  stacking is to combine multiple observations into
  a single result.
• Total deformation at Larissa estimated with
  interferometric stacking technique, November 1992
  October 2010 , (29 interferograms)
• 
  
  

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Techniques of SAR Interferometry (5/6)

• Persistent Scatterers Interferometry (PSI)
• This technique exploits temporal and spatial
  characteristics of interferometric signatures,
  collected from point targets.
• Distribution of geo-coded radar targets
  (persistent scatterers) in Larissa basin. The
  average in line of sight (LOS) velocity for the
  period (19952006) number of points are 62551

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Techniques of SAR Interferometry (6/6)

• Small BAseline Subset
• (SBAS)
• DInSAR methodology
• has been applied
• first to investigate single
• deformation events.
• However, more recently, it has also been
  exploited to analyze the temporal evolution of
  the detected displacements via the generation of
  deformation time series.

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Software's are used in SAR Interferometry
(1/2)NEST (NEW ESA SATELLITE TOOL BOX)

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Software's are used in SAR Interferometry
(2/2)GAMMA Remote sensing

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Present and Future plans and strategy (1/4)

• The second paper will be submitted soon by me
  and Mr. Risto Kalliola.
• The third article will be sent to Mr. Risto
  Kalliola during upcoming two weeks

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Present and Future plans and strategy (2/4)

• Now a days I prepared with cooperation of Mr.
  Petteri, Mr. Risto the proposal to implement the
  next research which is entitled
• Generation and validation DEM from multi-
  seasons tandems in dense trees area using
  space-based SAR interferometry case study of
  Turku southwestern Finland
• I suggest to publish a new article in FENNIA
  journal (I have huge data has not been published
  yet neither in my PhD dissertation nor in any
  paper)

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Present and Future plans and strategy (3/4)

• I plan to use SAR Interferometric techniques to
  study the ground deformation of Finland coastline
  (Or Turku)and its impact on landscape.
• I suggest to use SAR Interferometric techniques
  for forest classification and mapping and
  additionally use the same techniques for
  lithology classification and mapping
• I plan to use SAR Interferometric techniques
  to study the time series of flooding in Amazonian
  river.

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Present and Future plans and strategy (4/4)

• I Propose to present small seminar of InSAR
  within the topic of method in Remote Sensing
  number one or two.
• I Suggest to create workshop titled Radar
  Remote Sensing and SAR Interferometry

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• I would like to express my hope to a further
  collaboration with you
• Thank you for your attention
• Kiitos paljon,
• Kysymykset