Orthorectified Mosaic for Asia and Australia
Masanobu ShimadaJAXA/EORC
K&C 10 at RESTEC HQJune 24 2008
Contents of talk
•Path Processing of the all the SAR modes (FBS, FBD, POL, SCAN)
•Ortho-rectification of the path products
•Mosaicking
•Geometric evaluation and radiometric equalization
•Conclusion
Algorithms
•Slant range path products (~thousand km for STRIP and SCAN)•Segmented (16K) Doppler parameters and antenna pattern•Averaging with 16 look in azimuth and 4 look in range•Small segment based interference suppression•Small segment based saturation correction•Multi PRF imaging based on the motion compensation•Antenna pattern normalization based on the Amazon
•Geo-referenced ortho path data using the SRTM DEM•Precise matching using the segmented Doppler•Time shift tuning in Az. and Rg.•Projection from the slant range to ground range ortho path
•Mosaicking process•Normalization of the σ0 or conversion to γ0
•Pasting the above path data on a campus•Geo-coding it to the final coordinates
STRIP mode imaging (Radiometry)STRIP mode imaging (Radiometry)
•Raw data scaling
•Antenna Correction(Before azimuth correlation)
•POL mode
Pi, j ≅ a Gele2
R2sinθinci
σ i, j0 + Ni, j•Power
i, j : transmission and reception pol.Noise is not subtracted.
Sij = R−1 ⋅ Z ij ⋅ T−1
Vrawi, j =
1
GMGC T( )⋅ Pt Pt( ) 1−Sa t,T( ){ }v − v( )σ l
σ q
⎡
⎣ ⎢
⎤
⎦ ⎥
i, j
E i, j
Vrgi, j
=R sinθinci
Gelei, j φoff ,beam( )
Vrgi, j
E =σV σ H 0
0 1⎛
⎝ ⎜
⎞
⎠ ⎟ vraw:raw data voltage
vrg:volt after range corr.p:powerS:caled scattering matrixZ:uncal scattering matrix
R:slant rangeθinci:incidence angleφoff:off nadir angleσ0:sigma-naught
Calibration targetGele:antenna patternR,T:distortion matrixa:coefficients
Raw data scaling
Antenna Correction(Before azimuth SPECAN)
Pi, j ≅ a Gele2 ⋅ Naz
2
R4sinθinci
σ i, j0 + Ni, jPower
i, j : transmission and reception pol.Noise is not subtracted.
Vrawi, j =
1
GMGC T( )⋅ Pt Pt( )⋅ 1−Sa t,T( ){ }v − v( )σ l
σ q
⎡
⎣ ⎢
⎤
⎦ ⎥
i, j
E i, j
Vrgi, j
=R sinθinci
Gelei, j φoff ,beam( )
Vrgi, j
E =σV σ H 0
0 1⎛
⎝ ⎜
⎞
⎠ ⎟ vraw:raw data voltage
vrg:volt after range corr.p:powerS:caled scattering matrixZ:uncal scattering matrix
R:slant rangeθinci:incidence angleφoff:off nadir angleσ0:sigma-naught
Calibration targetGele:antenna patternR,T:distortion matrixa:coefficients
SCAN mode imaging (Radiometry)SCAN mode imaging (Radiometry)
Multi PRF processing
prf1
prf2
prf3
Time
Raw+range
prf1
prf1
prf1
16k
interpolation Azimuth
f (x) = g xi( )i= 0
7
∑ sin(x − xi)x − xi
8th order sinc interpolation for complex
Prf changes up to 7 times in descending or ascending node
Geo-locations and Calibration factors
IRF
GAMMA-naught vs. incidence for HH and HV
Old Antenna pattern New Antenna pattern
Before Aug. 7 2006 After Aug. 7 2006
GAMMA and SIGMA vs. incidence angle
Comparison of ortho projections
ϕ
λ⎛ ⎝
⎞ ⎠ =
tan−1 Ra2 Rb
2 ⋅ tanφ( )λ
⎛ ⎝ ⎜
⎞ ⎠ ⎟ =
tan−1 Ra2 Rb
2 ⋅ zg xg2 + yg
2( )tan−1 yg xg( )
⎛
⎝ ⎜ ⎞
⎠ ⎟
S' =cos γ sinγ
− sinγ cosγ⎛ ⎝
⎞ ⎠ S − Sc( )+ Sc
S = Raλ, Ra ln tanπ
4+
ϕ
2⎛ ⎝
⎞ ⎠
1 − esin ϕ
1 + esin ϕ⎛ ⎝
⎞ ⎠
e
2⎛
⎝ ⎜ ⎜
⎞
⎠ ⎟ ⎟
Map projection
Several maps are avilable(Mercator, LCC, equal lat-lon, PS, UTM)
Geodetic lat and lon
New cordinate suing the emean inclination(γ)’
HereS: Mercator coordinateRa:radius of equator、Rb: polar radiusΛ:londitude,ψ:geodetci lattitude,φ:geocentric latitudeE:eccentricity
γ
Final coordinate:S
S’
South East Asia mosaic for South East Asia using FBD
Evaluation : Geometry and radiometry in Mosaic
STRIP mode imaging (Range Doppler)
Conclusions
As the basic products for the K&C project, JAXA prepared the mosaic data sets for these regions.
The data products have geometric accuracies of less than 50 meters.
The data are projected onto the equal lat-lon coordinates.
SRTM data are used for generation of the ortho rectification.
(Biwa Lake)
(Daisen)
Attenuator: Auto
Attenuator: 25 dB
Before:too large Receive gain, saturationー>After ATT tuning, no more large saturation
Sigma naught
Evaluation of calibration:Incidence angle dependency of the Amazon sigma-naught, and noise equivalent sigma zero
SCANSAR NESZ
Gamma naught
-23 dB
GAMMA-naught vs. incidence for HH and HV (NEW)
Flat in incidence angle