Synthetic Aperture Radar (SAR)

Transcription

1 Synthetic Aperture Radar (SAR) Ministry of Security and Public Administration National Disaster Management Institute

2 RADAR RAdio Detection And Ranging

3 RADAR An object-detection system that uses radio waves to determine the range, altitude, direction, or speed of objects It was developed by several nations before and during World War 2. The term RADAR itself was coined in 1940 by the United Navy

4 Wavelength

5 Passive vs. Active Satellite Passive satellite - reflect the incident electromagnetic radiation without any modification or amplification - It can not generate power they simply reflect the incident power - Optical satellites (Kompsat-2,3, Landsat, MODIS ) - Observation time: after sunrise until sunset - high spatial resolution Active satellite - Satellites which can transmit power - They can amplify or modify the incident signal for transmission - SAR satellites (Kompsat-5, ALOS-1, ENVISAT, TerraSAR-X) - Unlimited observation time - low spatial resolution - high expense

6 Synthetic Aperture Radar (SAR) SAR is a form of radar whose defining characteristic is its use of relative motion, between an antenna and its target region, to provide distinctive long-term coherent-signal variations, that are exploited to obtain finer spatial resolution that is possible with conventional beam-scanning means Frist citizen SAR satellite: SEASAT (1978, US) Resolution, Antenna length, high frequency, short wavelength Interferometry, Polarimetry: Phase Ragargrammetry: (Intensity)

7 Real vs. Synthetic

8 Real vs. Synthetic

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10 TanDEM-X: TerraSAR-X add-on for Digital Elevation Measurement m COSMO-SkyMed : Constellation of small Satellites form the Mediterranean basin Observation

11 SRTM (Shuttle Radar Topography Mission, JPL, NASA) 60m mast 3 arc second data 90*90m, Global 1 arc second data 30*30, USA

12 Antenna type Radarsat-2 (15m*1.5m) TerraSAR-L (11m*2.9m) Pi-SAR2 (Airborne)

13 SAR observation mode Type of Mode 1. Spotlight 2. Stripmap 3. Scansar

14 SAR principle Side-looking system Difference between SAR and Optical imagery Radar reflection pattern

15 SAR distortion

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17 Interferometry SAR imagery is recoded the pixel information by complex value Optical imagery is recoded the reflected power from ground object Complex Number intensity phase Radar reflection from Object Distance between senor and object

18 Interferometry flat topo defo atm noi Interferometric SAR is the interferometric phase flat is the flat earth phase topo is the topographic phase defo is the deformation phase atm is the atmospheric delay phase noi is the noise.

19 Interferometry

20 flat topo defo atm noi InSAR (IfSAR) : Interferometric Synthetic Aperture Radar DInSAR : Differential Interferometric Synthetic Aperture Radar PSI (PSInSAR) : Persistent Scatterer Interferometric SAR SqeeSAR SBSA (Small baseline) PolSAR : Polarimetric SAR

21 Different reflection due to wavelength

22 Signal reflection Smooth Specular Intermediate Specular and Diffuse Rough Diffuse

23 DEM generated by different band L-band elevation model X-band elevation model

24 Polarimetry

25 Polarimetric AIRSAR San francisco, USA

26 PSI (PSInSAR) Sydney, Australia Ground subsidence at underground mining area

27 SK image, Brisbane, Queensland, ustralia CSK image, Brisbane, Queensland, Australia

28 Flooding at Queensland, Australia Intensity image analysis

29 Flood at Queensland, Australia Coherence analysis and Vegetation analysis

30 Flood at Queensland, Australia CSK, Rockhampton, Queensland, Australia BBC international internet.

31 Flood Queensland, AU MODIS Aqua imagery

32 Flood in Germany MODIS Terra imagery

33 Flood map in Germany (Optical image)

34 Flood map in Czech Republic (RADARSAT-2)

35 Earthquake detection

36 Sichuan Earthquake, China, 2008 Christchurch Earthquake, NZ,2011

37 SAR Intensity image analysis China earthquake Barrier lake due to earthquake

38 DEM generation

39 Oil spill disaster ERS-1 data ENVISAT data X-,C-band (3, 5cm)

40 Oil spill disaster in Korea, 2007 ENVISAT ASAR, ESA

41 PSI result in Busan

42 Bushfire monitoring (Multispectral image)