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