the ramses multi-pass interferometry campaign in...
TRANSCRIPT
The RAMSES multi-pass interferometry campaign in X-band
FRINGE 2007Sébastien Angelliaume, Hélène Oriot, Xavier Dupuis
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Outline of the presentation
• The campaign• RAMSES• Imaged Sites
• Processing• SAR processing• trajectory adjustment
• Temporal decorrelation and permanent scatterers in X band HR SAR imagery
• Oil storage tank filling
• Conclusion
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The sensor
ONERA / RAMSES
* P, L, X, Ku : GMTI capabilityX, Ku, Ka : Interferometry capability
•Multi-band•Very high resolution•Polarimetric•Interferometric•Multi-channel
Band P*
0,43GHz
70MHz
V / H
V and H
L*
1,3GHz
200MHz
V / H
V and H
S
3,2GHz
300MHz
V / H
V and H
C
5,3GHz
300MHz
V / H
V and H
X*
9,6GHz
1200MHz
V / H
V and H
Ku*
14,3GHz
1200MHz
V / H
V and H
Ka*
35GHz
1200MHz
V or H
V and H
W
95GHz
500MHz
L or R
L and R
CenterFrequency
Bandwidth
TransmitPolarization
ReceivePolarization
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Salon de Provence• Town• Flat, sloppy and montaneous area
Fos sur Mer• oil storage tank area
Puylaurent•mountaneaous area with a dam
Séchilienne•mountaneous area•landslide
The campaign (1/2)
from november 2005 to november 2006
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The campaign (2/2)
X band
Resolution (HR & VHR) : 1 agility : 0.5m (264 MHz).2 agilities : 0.26m (504 MHz) on La Séchilienne
Incidence angles : 75, 60 and 40°.
Ping pong mode for instantaneous interferometry
Multi-pass airborne interferometry• Each flight composed of 4 to 6 passes with the same configuration• 3 flights with a one day to one week delay• Flights several months apart on Séchilienne
Challenges:• Altitude ambiguity monitoring
• flight precision : performant DGPS/INS on board
• Processing of HR interferograms with non linear trajectories
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Fos sur Mer : instantaneous interferometry
Amplitude image
Interferogram : Ha ≈ 50m
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Salon de Provence : instantaneousinterferometry
Amplitude image
interferogram: Ha ≈ 50m
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Séchilienne : instantaneous interferometry
Amplitude image
Interferogram : Ha ≈ 50m
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SAR Processing
• SAR processing with a common geometry (Pamela processor)• Focusing on DTED-2
Common geometry
P
Master trajectory
Slave trajectory
• Master and slave images processed so that thewavefronts on point P comingfrom M and S are tangencial
M
S
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Results of the processing
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Trajectory refinement
• modelling of the slave trajectory correction by a sum of cosinesfunctions
• Least square minimisation using the unwrapped interferogram
• Processing with the new slave trajectory
0 cm
10 cm
20 cm Example of trajectory refinement
Coherence analysis
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Coherence false color representation
Amplitude image
0 (no coherent) 1 (coherent)
Interferometric coherence
False color representation
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Coherent change detection : nature of the ground (1/4)
20 minutes 2 days
0 (no coherent) 1 (coherent)
Risk ofdecorrelation
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Very High Resolution : Séchilienne area
Coherence :
simultaneous acquisition
Coherence :
Half an hour
Coherence :
10 months
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Very High Resolution : Séchilienne area
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Very High Resolution : Séchilienne area
Coherence representation interferometric representation
10 months between the 2 acquisitions, in X-band
Permanent scatterers visible on 25 cm resolution images
Oil storage area
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Gas storage area
• Données amplitude
Simultaneousinterferogram : Ha ≈ 50 m
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Gas storage area
Interferogram
1 hour
Ambiguity altitude
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Residual interferogram
• Withdraw of oil storage altitude using the simultaneousinterferogram
• Phase variations are due to:• Residual altitude information due to the low ambiguity altitude of
the multi-pass interferogram• Misestimation of the trajectory• Atmospehric artefacts• Changes in the oil storage roofs
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Oil storage area analysis
Radar illumination direction
Range direction
R1 R2
R3 R4
Computation of φA – φC :
Computation of φB – φC
Local measure insensitive to• trajectory mis-estimation
• Atmospheric propagation artefacts
A B C
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Results
• Change detection on R2
• Consistent with ground truth• R2 was being emptied during the acquisition (roof displacement of
the order of 8cm)
• R1, R3 and R4 : no movement
10°2°166°31°Residual phase difference between top of the tank and floating roof
8°62°169°2.9°Residual phase difference between ground and floating roof
R4R3R2R1Tank #
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Conclusion
• Very interesting campaign
• Not completely exploited
• Main results• Coherence analysis for several temporal intervals
• Change detection on oil storage field
• Work is on going to further analyze the oil storage field
• ONERA has developed a new sensor for civilian applications : SETHI
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SETHI
Thank you for your attention …