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

3. ＩIGARSS 2011, Vancouver, Canada
Background
Agricultural field
Built-up Area
Freeman&Durden decomposition of ALOS PALSAR　data (Descend.)
Double-bounce, Volume, Surface
From map “Isezaki” by The Geospatial Information Authority of Japan (GSI)
Objective: To discriminate built-up and non-built-up areas
ＩIGARSS 2011, Vancouver, Canada

4. Polarization Orientation in Built-up Areas
Radar x
(azimuth) y
(range) V H k a f
From L-band Pi-SAR data of Gifu
• PO angle shift of built-up areas:
azimuth slope angle: w a , ground range angle: g =0,
radar look angel: f p/2-f .
a: 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.
• PO angle shift of terrain slopes:
w : azimuth slope angle,
g : ground range slope angle,
f : radar look angle.
ＩIGARSS 2011, Vancouver, Canada

5. Method to Discriminate Built-up and Non-built-up Area
• Detection of built-up areas facing away from the radar (|a|ac)
• Method to discriminate
Built-up areas: |qa|>c or |qd|>c.
Not built-up but level surface areas: |qa|c and |qd|c.
qa, qd : PO angles from ascending and descending orbits
c : PO angle threshold from wall orientation angle threshold ac
DETECTABLE zone of built-up areas
Illumination
Illumination
ASCENDING
UNDETECTABLE zone of built-up areas
DESCENDING
ＩIGARSS 2011, Vancouver, Canada

6. In case of SMALL threshold ac
DETECTABLE zone of built-up areas
DETECTABLE =
+ (OR)
UNDETECTABLE
ASCENDING
DESCENDING
• 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.
ＩIGARSS 2011, Vancouver, Canada

7. In case of LARGE threshold ac
DETECTABLE zone of built-up areas
DETECTABLE =
+ (OR)
UNDETECTABLE zone
UNDETECTABLE
ASCENDING
DESCENDING
• 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.
ＩIGARSS 2011, Vancouver, Canada

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

9. ALOS PALSAR Experiment: Images
Pauli color code Freeman&Durden decomposition PO angle
|HH-VV|, |HV|, |HH+VV| Double-bounce, Volume, Surface
-p/ p/4
ＩIGARSS 2011, Vancouver, Canada

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

11. Freeman&Durden DecompositionB3 B2 B1 F1
© Google Earth
Double-bounce Volume Surface
Google Earth image Ascending Descending
ＩIGARSS 2011, Vancouver, Canada

12. ＩIGARSS 2011, Vancouver, CanadaH a
H-Alpha Segmentation F3 F2 B3 B2 B1 F1
© Google Earth
Google Earth image Ascending Descending
ＩIGARSS 2011, Vancouver, Canada

13. ＩIGARSS 2011, Vancouver, Canada
PO Angle Images F3 F2 B3 B2 B1 F1
© Google Earth
-p/ p/4
Google Earth image Ascending Descending
ＩIGARSS 2011, Vancouver, Canada

14. Discrimination ResultsF3 F2 B3 B2 B1 F1
White: Built-up area, Black: Non-built-up area
c=5(ac=5 ) c=10(ac=9) c=12(ac=11)
ＩIGARSS 2011, Vancouver, Canada

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

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

17. Discrimination Results
Agricultural field
Built-up Area
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(ac=9).
ＩIGARSS 2011, Vancouver, Canada

18. Discrimination Results
Agricultural field
Built-up Area
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(ac=9).
ＩIGARSS 2011, Vancouver, Canada

19. ＩIGARSS 2011, Vancouver, Canada
Conclusion
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.
ＩIGARSS 2011, Vancouver, Canada

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

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