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Using SAR Intensity and Coherence to
Detect A Moorland Wildfire Scar
Presentation Structure
• Fire
– Fires & Moorlands
– UK Wildfires (news clip)
– Fire Scar Detection
• Research question & o...
Why Fire is Important in Moorlands?
Destroy vegetation
Fuel load, adaptation
Climate Wildlife
Vegetation
Soil
Humans
CO2 e...
UK Wildfires
Source: BBC News, 4 May 2011
http://www.bbc.co.uk/news/uk-13277476
UK Fire Scar Detection
Source: http://effis.jrc.ec.europa.eu/
Research Question (Pilot Study)
How well can the C-band SAR intensity and coherence
signal detect a fire scar within a deg...
Why SAR?
• See through cloud
and smoke
• Active sensor: acquire
images day and night
• Good temporal
resolution of data
• ...
SAR Interaction
Source: Landmap Radar Imaging Course
http://landmap.mimas.ac.uk
 
Study
AreaLongdendale
Nearest Neighbour resampling method
One image used as the input reference file, the
other image is coregistered to this.
E...
Intensity & Precipitation time series
Pre-
fire
Post-
fire
Intensity
& Land
Cover
Results
InSAR Pairs – Coherence Analysis
ERS-2 InSAR Pairs Orbit/ Track Baseline (m) Description
Pair 1
08/02/2003 /
15/03/2003
40...
Coherence Results
Summary & Conclusion
• Precipitation & land cover are key variables for
understanding the SAR intensity and coherence
– Wi...
Future Work
• Investigate fire scars of different sizes, severity, land
cover & precipitation conditions
• Analyse the aff...
Acknowledgements
Access to fire log and fire scar GPS data
PDNP Fire Operations Group
Access to ERS-2, ALOS PALSAR & ASAR ...
Thank you for Listening
Images for Intensity Analysis
SAR
Data/
Mode/
Swath
Acquisition
Date/Time
dd/mm/yyyy
Time
relative to
fire
(JD Julian
day)...
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Using SAR Intensity and Coherence to Detect A Moorland Wildfire Scar

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Presented at RSPSoc 2011 Annual Conference, Bournemouth University, UK

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Using SAR Intensity and Coherence to Detect A Moorland Wildfire Scar

  1. 1. Using SAR Intensity and Coherence to Detect A Moorland Wildfire Scar
  2. 2. Presentation Structure • Fire – Fires & Moorlands – UK Wildfires (news clip) – Fire Scar Detection • Research question & objectives (pilot study) • Methodology – Why SAR? – Study Site – SAR pre-processing chain • Results – Intensity – Coherence • Conclusion & Future Work
  3. 3. Why Fire is Important in Moorlands? Destroy vegetation Fuel load, adaptation Climate Wildlife Vegetation Soil Humans CO2 emissions Remove habitat Adaptation Managed burns Arson Degradation ErosionRate of re vegetation
  4. 4. UK Wildfires Source: BBC News, 4 May 2011 http://www.bbc.co.uk/news/uk-13277476
  5. 5. UK Fire Scar Detection Source: http://effis.jrc.ec.europa.eu/
  6. 6. Research Question (Pilot Study) How well can the C-band SAR intensity and coherence signal detect a fire scar within a degraded UK moorland environment? Objectives • Determine the ability of SAR intensity and InSAR coherence to detect the fire scar over time in a moorland environment • Analyse qualitatively how scene variables such as precipitation and CORINE land cover classes affect the SAR intensity and coherence signal, both inside and outside the fire scar
  7. 7. Why SAR? • See through cloud and smoke • Active sensor: acquire images day and night • Good temporal resolution of data • SAR very sensitive to moisture content ideal for mapping fire scars Source: Landmap Radar Imaging Course http://landmap.mimas.ac.uk
  8. 8. SAR Interaction Source: Landmap Radar Imaging Course http://landmap.mimas.ac.uk  
  9. 9. Study AreaLongdendale
  10. 10. Nearest Neighbour resampling method One image used as the input reference file, the other image is coregistered to this. ENVI Band Math using the formula 10*alog10(b1) Degraded to 100m using a Nearest Neighbour resampling method in ENVI. 5 backscatter sample points for each land cover class was extracted from the radar data. Equivalent looks variable set to -1 threshold for speckle filtering is calc by the software – 0.5227/sqrt Multitemporal DeGrandi Filter used 25m DEM No GCP (however a sub-pixel accuracy can still be achieved when DORIS data has been used) Generated Sigma Nought values Calculate Ground Range GR (m) = Rg ÷ sin IA Calculate number of Azimuth Looks = GR ÷ Az 1. Basic Import for ASAR or ERS-2 Single Look Complex (slc) Intensity Image (pwr) 3.A Amplitude Coregistration Resampled & resized images (rsp) Filtered image(fil) 5. Geocoding Radiometric Calibration Geocoded 25m images (geo) Level 1 SLC from ESA 4. Multi-temporal Despeckling 2. Focusing and Multilooking 6. Geocoded images to dB 100m Greyscale Geocoded SAR image Process Outputs/Inputs Processes Final Product Key 3. Amplitude Coregistration
  11. 11. Intensity & Precipitation time series Pre- fire Post- fire
  12. 12. Intensity & Land Cover Results
  13. 13. InSAR Pairs – Coherence Analysis ERS-2 InSAR Pairs Orbit/ Track Baseline (m) Description Pair 1 08/02/2003 / 15/03/2003 40801 & 41302 366 134 Pre-fire Pair 2 15/03/2003 / 19/04/2003 41302 & 41803 349 349 Pre & immediately post- fire Pair 3 19/04/2003 / 24/05/2003 41803 & 42304 366 147 Post-fire Pair 4 24/05/2003 / 28/06/2003 42304 & 42805 366 654 Post-fire
  14. 14. Coherence Results
  15. 15. Summary & Conclusion • Precipitation & land cover are key variables for understanding the SAR intensity and coherence – Within the fire scar peat bog gave highest intensity return – Rainfall just prior to image acquisition increased intensity values for all land cover classes inside the fire scar • Image results are sensitive to: – Filtering algorithm applied > recommend Degrandi multitemporal – Initial baseline of InSAR pairs > temporal decorrelation • A large fire scar in a degraded moorland environment can be detected using SAR intensity. InSAR coherence needs to be further explored.
  16. 16. Future Work • Investigate fire scars of different sizes, severity, land cover & precipitation conditions • Analyse the affect of radar polarisation and frequency on fire scar detection – X band & L band data – Cross polarised and co-polarised data • Applying classification method for fire scar mapping • Explore Kinder 2008 & Wainstalls 2011 case studies – GPS boundary collected this summer – Kinder boundary obtained from MFF
  17. 17. Acknowledgements Access to fire log and fire scar GPS data PDNP Fire Operations Group Access to ERS-2, ALOS PALSAR & ASAR data as part of Category 1 Project 2999 School of Environment & Development for funding to support this research Mimas & Landmap for funding, time & resources to support this research References KEELEY, J. (2009) Fire intensity, fire severity and burn severity: a brief review and suggested usage. International Journal of Wildland Fire, 18, 116-126. LENTILE, L. B et al., (2006) Remote sensing techniques to assess active fire characteristics and post-fire effects. International Journal of Wildland Fire, 15, 319-345. Martin Evans & Juan Yang at SED for Upper North Grain weather data
  18. 18. Thank you for Listening
  19. 19. Images for Intensity Analysis SAR Data/ Mode/ Swath Acquisition Date/Time dd/mm/yyyy Time relative to fire (JD Julian day) Incidence Angle (IA) Az pixel spacing (m) Rg pixel spacing (m) Ground Range (GR) (m) Pass Type ERS-2 08/02/2003 11:01 -69 days (39 JD) 23.23º 3.97 7.90 20.26 Desc- ending ERS-2 15/03/2003 11:01 -34 days (74 JD) 23.23º 3.97 7.90 20.26 Desc- ending ASAR IM I2 22/03/2003 21:37 -27 days (81 JD) 22.82º 4.04 7.80 20.00 Asc- ending ASAR AP I2 HHVV 03/04/2003 10:36 -15 days (93 JD) 22.76º 4.04 7.80 20.00 Desc- ending ERS-2 24/05/2003 11:01 +36 days (144 JD) 23.21º 3.97 7.90 20.26 Desc- ending ERS-2 28/06/2003 11:01 +71 days (179 JD) 23.28º 3.97 7.90 19.75 Desc- ending

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