1 4th TanDEM-X Science Team Meeting, 10-14 June 2013, German Aerospace Center (DLR)
Andrei ANGHEL1, Gabriel VASILE2, Guy d’URSO3, Remy BOUDON3, Didier BOLDO3, Jean Philippe OVARLEZ4, Irena HAJNSEK5
1 GIPSA-lab / University Politehnica of Bucharest2GIPSA-lab, French National Council for Scientific Research (CNRS)
3Électricité de France (EDF)4ONERA
5German Aerospace Center (DLR)
SAR images refocusing on specific grids for interferometric processing
2 4th TanDEM-X Science Team Meeting, 12-14 June 2013, German Aerospace Center (DLR)
On Off
SAR Image Grid
-Grid Reflectors.
Off-grid reflectors:• Loss of contrast.• Ambiguous phase.• False target detections.
3 4th TanDEM-X Science Team Meeting, 12-14 June 2013, German Aerospace Center (DLR)
SAR Image Defocusing
Focused SAR Image
Flight Path
Defocusing RAW data
0.5 1 1.5 2 2.5
x 104
0.5
1
1.5
2
2.5
x 104
4 4th TanDEM-X Science Team Meeting, 12-14 June 2013, German Aerospace Center (DLR)
SAR Image Refocusing
Refocused SAR Image ona specific grid.
Flight Path
Refocusing
RAW data
New grid
0.5 1 1.5 2 2.5
x 104
0.5
1
1.5
2
2.5
x 104
x [m]
y [m
]
Refocused SAR Image [dB]
-100 -50 0 50 100
-100
-50
0
50
100 -40
-35
-30
-25
-20
-15
-10
-5
0
5 4th TanDEM-X Science Team Meeting, 12-14 June 2013, German Aerospace Center (DLR)
X-band Ground-based SAR Imaging System1
Range [m]C
ross
-Ran
ge [m
]
SAR Image
0.5 1 1.5 2 2.5 3-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
-25
-20
-15
-10
-5
0
1Andrei Anghel, Gabriel Vasile, Remus Cacoveanu, Cornel Ioana, Silviu Ciochina, “Short-Range Wideband FMCW radar for millimetricdisplacements measurement”, submitted to IEEE Transactions on Geoscience and Remote Sensing.
6 4th TanDEM-X Science Team Meeting, 12-14 June 2013, German Aerospace Center (DLR)
Ground-based SAR Images Refocusing (1)
Range [m]
Cro
ss-R
ange
[m]
SAR Image
0.5 1 1.5 2 2.5 3-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
-25
-20
-15
-10
-5
0
Defocusing Refocusing on a different grid
x [m]
y [m
]
Refocused SAR Image
0.5 1 1.5 2 2.5-0.5
0
0.5
1
-25
-20
-15
-10
-5
0
Computing the response fromeach pixel on the syntheticaperture elements.
Applying the back-projectionalgorithm on the de-chirpedraw data (the defocusedimage).
7 4th TanDEM-X Science Team Meeting, 12-14 June 2013, German Aerospace Center (DLR)
x [m]
y [m
]
Refocused SAR Image
0.5 1 1.5 2 2.5-0.5
0
0.5
1
-25
-20
-15
-10
-5
0
Ground-based SAR Images Refocusing (2)
Range [m]
Cro
ss-R
ange
[m]
SAR Image
0.5 1 1.5 2 2.5 3-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
-25
-20
-15
-10
-5
0
Defocusing Partial Refocusing on a different grid
Selecting only a certain targetfrom the initial image (using abinary mask).
Applying the back-projectionalgorithm on the de-chirpedraw data (the defocusedimage).
8 4th TanDEM-X Science Team Meeting, 12-14 June 2013, German Aerospace Center (DLR)
Ground-based SAR Refocused Images Interferogram
Range [m]
Cro
ss-R
ange
[m]
Coherence
1 1.5 2 2.5 3 3.5
-1
-0.5
0
0.5
1 0
0.2
0.4
0.6
0.8
1
Range [m]
Cro
ss-R
ange
[m]
Interferogram (rad)
1 1.5 2 2.5 3 3.5
-1
-0.5
0
0.5
1 -3
-2
-1
0
1
2
3
1 2 3 4 50
1
2
3
4
LOS
Dis
plac
emen
t (m
m)
n
realmeasured
1 2 3 4 50
0.02
0.04
0.06
0.08
Abs
olut
e er
ror (
mm
)
n
9 4th TanDEM-X Science Team Meeting, 12-14 June 2013, German Aerospace Center (DLR)
Spotlight High-Resolution TerraSAR-X images (300 MHz)
10 4th TanDEM-X Science Team Meeting, 12-14 June 2013, German Aerospace Center (DLR)
Focused TerraSAR-X spotlight image
RAW Data Corrections:-Taylor approximation in ECS.-Element pattern of antenna array.-Curved orbit compensation.-Stop-and-Go Approximation.-Tropospheric effects.
Spotlight RAW Data
Extended Chirp Scaling Algorithm 2
Focused Image
Corrected RAW data
For staring spotlight 1
1Pau Prats-Iraola, Rolf Scheiber, Marc Rodrıguez-Cassola, Steffen Wollstadt, Josef Mittermayer, Benjamin Brautigam, Marco Schwerdt, Andreas Reigber and Alberto Moreira, “High Precision SAR Focusing of TerraSAR-X Experimental Staring Spotlight Data”, in Proc. IGARSS’12, Munich, Germany, pp. 3576-3579.
2Alberto Moreira, Josef Mittermayer and Rolf Scheiber, “Extended Chirp Scaling Algorithm for Air- and Spaceborne SAR Data Processing in Stripmapand ScanSAR”, IEEE Transactions on Geoscience and Remote Sensing, Vol. 34, No. 5, Sept. 1996, pp. 1123-1136.
11 4th TanDEM-X Science Team Meeting, 12-14 June 2013, German Aerospace Center (DLR)
Refocusing TerraSAR-X images
SAR Image
Reversed Extended Chrip Scaling
Algorithm
De-chirping
RAW data
De-chirped RAW data
Back-projection algorithm
Grid Points
Reading Parameters from XML file: Central Frequency Chirp Bandwidth RSF PRFs Scene Coordinates ...
Refocused SAR Image
Extended CSA: FFTs/IFFTs Complex multiplications
12 4th TanDEM-X Science Team Meeting, 12-14 June 2013, German Aerospace Center (DLR)
Refocusing TerraSAR-X images : First Results (1)
Range [m]
Azi
mut
h [m
]
-2000 -1000 0 1000 2000
-2000
-1000
0
1000
2000
Flight PathR0 θ
Refocused Area
New Grid
13 4th TanDEM-X Science Team Meeting, 12-14 June 2013, German Aerospace Center (DLR)
Range [m]
Azi
mut
h [m
]
-1600 -1500 -1400 -1300 -1200 -1100 -1000
-1500
-1400
-1300
-1200
-1100
-1000
-900
-800
-700
-600
x [m]
y [m
]
Refocused SAR Image [dB]
-500 0 500
-500
-400
-300
-200
-100
0
100
200
300
400
500
Refocusing TerraSAR-X images : First Results (2)
Initial Image [dB]
40 dB dynamic range
14 4th TanDEM-X Science Team Meeting, 12-14 June 2013, German Aerospace Center (DLR)
Lon [deg]
Lat [
deg]
Refocused SAR Image [dB]
3.71 3.7105 3.711 3.7115 3.71244.4395
44.44
44.4405
44.441
44.4415
-40
-35
-30
-25
-20
-15
-10
-5
0
Flight Path
Further Research (1)
• The resolution issues in the refocusing process.• Refocus the raw data in latitude-longitude geometry using a GPS-measured grid.• Employ interferometric processing on refocused images.
15 4th TanDEM-X Science Team Meeting, 12-14 June 2013, German Aerospace Center (DLR)
Further research (2): Puylaurent dam displacementsmeasurement with TanDEM-X
GPS-measured points on the dam’s ridge.
Refocusing TanDEM-X images on the measured points.
Dam’s ridge displacements monitoring.
16 4th TanDEM-X Science Team Meeting, 12-14 June 2013, German Aerospace Center (DLR)
Thanks for your attention !!!
Questions ? Suggestions ?