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Geocoding UAVSAR Data Products
Yang Zheng, Ron Muellerschoen, Thierry Michel,
Bruce Chapman, Scott Hensley, Yunling Lou
Jet Propulsion Laboratory, California Institute of Technology
August 26, 2010
Outline
UAVSAR Introduction
Flight Summary
UAVSAR Data Products
Geocoding Algorithm
Summary
UAVSAR
UAVSAR - Uninhabited Aerial Vehicle Synthetic Aperture Radar
Airborne L-band, fully-polarimetric SAR
Designed for repeat pass interferometry
Flight path within 10m tube using precision real-time
GPS and sensor controlled flight management system
UAVSAR Parameters
Nominal altitude: 12,497 m (41,000 ft)
Center frequency: 1.2575 GHz
Bandwidth: 80 MHz
Transmit Power: > 3.1 kW
Range resolution: 1.67 m
Azimuth resolution: 0.6 m
Incidence angle: 25 – 65 degrees
G-III aircraft with UAVSAR pod
flight track within 10 meter tube
Flight Summary
UAVSAR operational since May, 2009
Countries visited:
Greenland
Iceland
Canada
USA
Emergency response: Haiti & Mexicali earthquakes, Gulf oil spill
Disciplines
Terrestrial Ecology
Crustal Deformation: Earthquake, Volcanoes, Delta, Gulf Coast
Applications: archaeology, structure integrity, levees monitor, ocean eddies &
tidal study, carbon sequestration, oil spill
UAVSAR acquisitions as of June, 2010:
131 flights
734 flight hours
1011 L-band science data lines
Costa Rica
Panama
Guatemala
Honduras
Nicaragua
El Salvador
Haiti
Dominican Republic
3.1 million km2 imaged
(140,000 km along track)
644 science data lines processed & released
Flight Coverage Map
http://uavsar.jpl.nasa.gov
UAVSAR PolSAR Products
Slant range multi-looked products
HHHH
HVHV
VVVV
Compressed stokes matrix (AIRSAR format)
Ground range products
HHHH
HVHV
VVVV
Interpolated DEM
KMZ of three polarization color overlay of
HHHH, HVHV, and VVVV
Metadata – annotation file
HHHV
HVHV
HVVV
HHHV
HVHV
HVVV
Gulf Coast, Sep 2, 2009
Gulf Spill Buoys in PolSAR Image
UAVSAR RPI Products
Slant range multi-looked products
Interferogram
Unwrapped phase
Correlation
Amplitudes
Ground range products
Interferogram
Unwrapped phase
Correlation
Amplitudes
Interpolated DEM
KMZ of all above products
Metadata – annotation file
interferogram
unwrapped phase
correlation
amplitude
interpolated DEM
Geocoding UAVSAR Data
Find latitude & longitude boundaries that cover the entire slant range
image and determine latitude & longitude spacing that results in
approximately square ground pixels.
latitude spacing: 0.2 arcsec (~6 m)
longitude spacing: variable based on latitude of data take
For each point on the ground range grid, calculate the corresponding
slant range indices.
Using nearest neighbor method, the data value closest to the
calculated slant range indices is assigned to the point on the ground
range grid.
latitude (deg) 0 - 50 50 - 70 70 - 75 75 - 80 80 - 90
longitude spacing (arcsec) 0.2 0.4 0.6 0.8 1.2
Geocoding Zero Doppler Data
PolSAR slant range data are deskewed to zero Doppler
where
((hp rE )2 (ht rE )
2 2(hp rE )(ht rE )cos(C /rE ))1/ 2
hp
rE
ht
range
hp height of platform
ht height of terrain
rE radius of the earth
C cross track position in SCH coordinates
Geocoding Non-Zero Doppler Data
RPI slant range data are skewed with global Doppler
where
iterate to find using Newton-Raphson method
r P
r T
ˆ n
referencetrack
r T
r P
r T
r P , ˆ n sin 0
r P platform location vectorr T ground projection location vector
electronic steering angle
ˆ n unit vector normal to image plane
( function of yaw and pitch )
r P
Geocoding Accuracy
Corner reflectors deployed in Rosamond
dry lake bed, CA were used to verify
geocoding results
Corner reflector survey position accuracy
(measured at vertex using differential GPS):
s= 10 cm
Geocoded vs. measured CR location
LatitudeAverage
Error
Standard Deviation
of Error
degrees -8.946E-06 1.21817E-05
pixels 0.161015119 0.21925381
LongitudeAverage
Error
Standard Deviation
of Error
degrees 5.94E-06 1.4697E-05
pixels 0.106911447 0.26452422
Future Work
Use interpolation instead of nearest neighbor method for
geocoding
Provide more product layers such as
local incidence angle map
line of sight displacement
phase slope corrected correlation
Thank You!
Copyright 2010 California Institute of Technology. Government sponsorship acknowledged.
