1. On The Use of Polarimetric Orientation for POLSAR Classification and Decomposition Hiroshi Kimura Gifu University, Japan IGARSS 2011 Vancouver, Canada July 25, 2011

2. Contents Background Polarization Orientation in Built-up Areas Method to Discriminate Built-up and Non- built-up Areas ALOS PALSAR Experiment Conclusion Ｉ IGARSS 2011, Vancouver, Canada

3. Background Freeman&Durden decomposition of ALOS PALSAR data (Descend.) Double-bounce, Volume, Surface From map “Isezaki” by The Geospatial Information Authority of Japan (GSI) Agricultural field Built-up Area Objective: To discriminate built-up and non-built-up areas

4. Polarization Orientation in Built-up Areas PO angle shift of terrain slopes:  : azimuth slope angle,  : ground range slope angle,  : radar look angle. Radar x (azimuth) y (range) V H k   z PO angle shift of built-up areas: azimuth slope angle:  ground range angle:  radar look angel:   wall orientation angle from the normal of radar beam  H. Kimura, “Radar polarization orientation shifts in built-up areas,” IEEE GRSL, vol. 5, no. 2, 2008. From L-band Pi-SAR data of Gifu Ｉ IGARSS 2011, Vancouver, Canada

5. Method to Discriminate Built-up and Non-built-up Area Ｉ IGARSS 2011, Vancouver, Canada Detection of built-up areas facing away from the radar (|  |  c ) Method to discriminate Built-up areas:  a  c  or  d  c  Not built-up but level surface areas:  a  c and  d  c   a,  d : PO angles from ascending and descending orbits  c : PO angle threshold from wall orientation angle threshold  c Illumination UNDETECTABLE zone of built-up areas DETECTABLE zone of built-up areas ASCENDING DESCENDING

6. Ｉ IGARSS 2011, Vancouver, Canada In case of SMALL threshold In case of SMALL threshold  c  (OR) ASCENDING DESCENDING DETECTABLE zone of built-up areas  NO undetectable zone of built-up area COMMISSION error (Non-built-up areas are assigned to built-up areas) increases. OMSSION error (Built-up areas are assigned to non-built-up areas) decreases. UNDETECTABLE DETECTABLE

7. Ｉ IGARSS 2011, Vancouver, Canada In case of LARGE threshold In case of LARGE threshold  c  (OR) ASCENDING DESCENDING DETECTABLE zone of built-up areas  UNDETECTABLE zone Undetectable zone of built-up area exists. COMMISSION error (Non-built-up areas are assigned to built-up areas) decreases. OMSSION error (Built-up areas are assigned to non-built-up areas) increases. UNDETECTABLE DETECTABLE

8. ALOS PALSAR Experiment: PALSAR Scenes Ｉ IGARSS 2011, Vancouver, Canada The Atsugi area: about 50 km south- west from Tokyo Radar illumination azimuth: 99  (Ascending) 261  (Descending) Expected  c is 9  (No undetectable zone and the max.  c ), then the PO angle threshold c will be 10 .

9. ALOS PALSAR Experiment: Images Ｉ IGARSS 2011, Vancouver, Canada Pauli color code Freeman&Durden decomposition PO angle |HH-VV|, |HV|, |HH+VV| Double-bounce, Volume, Surface 

10. Study Area ( 5.2km by 3.1 km ) Ｉ IGARSS 2011, Vancouver, Canada B3 F3 B2 B1 F2 F1 Google Earth image Map by GSI, Japan B3 F3 B2 B1 F2 F1 © Google Earth

11. Freeman&Durden Decomposition Ｉ IGARSS 2011, Vancouver, Canada Google Earth image Ascending Descending B3 F3 B2 B1 F2 F1 Double-bounce Volume Surface © Google Earth

12. H-Alpha Segmentation Ｉ IGARSS 2011, Vancouver, Canada H  Google Earth image Ascending Descending © Google Earth B3 F3 B2 B1 F2 F1

13. PO Angle Images Ｉ IGARSS 2011, Vancouver, Canada  Google Earth image Ascending Descending © Google Earth B3 F3 B2 B1 F2 F1

14. Discrimination Results Ｉ IGARSS 2011, Vancouver, Canada c=5  (  c =5  ) c=10  (  c =9  ) c=12  (  c =11  ) White: Built-up area, Black: Non-built-up area B3 F3 B2 B1 F2 F1

15. Discrimination Results (Built-up areas) Ｉ IGARSS 2011, Vancouver, Canada © Google Earth B1 B2 B3 White: Built-up area Black: Non-built-up area Google Earth image c=5  (  c =5  ) c=10  (  c =9  ) c=12  (  c =11  ) Omission errors

16. Discrimination Results (Non-built-up areas) Ｉ IGARSS 2011, Vancouver, Canada © Google Earth F1 F2 F3 Commission errors White: Built-up area Black: Non-built-up area Google Earth image c=5  (  c =5  ) c=10  (  c =9  ) c=12  (  c =11  )

17. Discrimination Results Ｉ IGARSS 2011, Vancouver, Canada Freeman&Durden decomposition of ALOS PALSAR data (Descend.) Double-bounce, Volume, Surface Built-up Areas (white) and non- built-up areas (black) by c=10  (  c =9  ). Agricultural field Built-up Area

18. Discrimination Results Ｉ IGARSS 2011, Vancouver, Canada Freeman&Durden decomposition of ALOS PALSAR data (Ascend.) Double-bounce, Volume, Surface Built-up Areas (white) and non- built-up areas (black) by c=10  (  c =9  ). Agricultural field Built-up Area

19. Conclusion Ｉ IGARSS 2011, Vancouver, Canada  PO from ascending and descending orbits can be used to discriminate built-up and non-built-up areas.  Radar illumination direction influences POLSAR data aanlysis.  The discrimination prevents misleading of POLSAR decomposition and classification. (Volume scattering in urban areas, double bounce in agricultural fields, et al.)  The expected threshold with no undetectable zone of built-up areas and the maximum number seems to be good, but a further study is required for the best one.  Slopes should be separated.

20. Rotation of Coherence Matrix (Yamaguchi) Ｉ IGARSS 2011, Vancouver, Canada BEFORE Rotation AFTER Rotation Agricultural fields Built-up Areas |HH-VV| |HV| |HH+VV| Ascending Descending |HH-VV| |HV| |HH+VV| Ascending Descending

21. Ｉ IGARSS 2011, Vancouver, Canada Range Slope Angle (degrees) PO Angle Shifts of Slopes