Remi MICHEL1, Jean-Philippe AVOUAC1 and Jean TABOURY2
1 Laboratoire de Detection et de Geophysique, CEA, BP 12, 91680 Bruyeres le Chatel Cedex, FRANCE. email: email@example.com . tel: 33-01-69-26-62-76. fax: 33-01-69-26-70-23.
2 Institut díOptique- SupOptique, 91403 ORSAY Cedex, FRANCE.
We propose a method to compute interferograms from Synthetic
Aperture Radar images that significantly reduce the phase noise
while preserving spatial resolution. The procedure starts from
two Single Look Complex images noted a and b. We give usefull
results about interferometry with ERS-1. The non common spectral
bands of the images are suppressed. Disparities between the two
images are computed using the Fourier transform of the images
amplitudes within a slidding window. The images are then registred
within 1/10 of pixel using an exact formulation for resampling.
The images are over-sampled by a factor two and a raw interferogram
is computed. We show that the main source of noise is due to the
poorly constrained phase at points where the amplitude of the
interferogram is low, i.e. at the speckle grains boundaries. We
therefore filter the interferometric phase using a weighting function
that depends on the amplitude of the interferogram. The adaptative
filtering also takes into account the local slope. The averaging
window is choosen in order to preserve the maximum spatial resolution.
The filter remains efficient on areas of narrow fringes and high
temporal decorrelation. Example using ERS-1 SAR data are discussed.
keywords: SAR interferometry, image registration, adaptive phase filtering
Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry
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