Télédétection de la surface terrestre par un radiomètre imageur à synthèse d'ouverture : principes de mesure, traitement des données interférométriques et méthodes de reconstruction régularisées

Abstract : he European Space Agency is currently developing the SMOS (Soil Moisture and Ocean Salinity) mission
as the first attempt to obtain global measurements of soil moisture and ocean salinity. This mission is based
on a promising technology, a synthetic aperture imaging radiometer (SAIR), initially developed in radio-astronomy.
The main subject of this thesis consists on a study of regularized reconstruction methods allowing to establish
brightness temperature maps from the interferometric data provided by the instrument.

The principle of measurement is quite different from those commonly used in Earth remote sensing. A first part
is thus dedicate to introduce the fundamental mechanisms of passive interferometry, through the study of
the measurement line, a recall of Young's "double slit" experiment and of the properties of the 2D Fourier transform.

The processing of the interferometric data needs a strict geometrical and algebraic frame as describe in a second part.
the inferred oscillations appearing in reconstructed maps. The apodization windows are characterized
for two possible configurations of the antenna array. As the estimation of the geophysical parameters
need the processing of brightness temperature maps defined on regular grids with isotropic spatial resolution,
we have introduce resampling techniques and a strip-adaptive processing.

The inverse problem to be solved is ill-posed and the existence and the uniqueness of the solution
have therefore to be guaranteed. This is the main goal of the regularized reconstruction methods,
which are defined and compared in a third part. Then, these methods are used to characterize
several problems related to the image reconstruction for SAIR. Thus, the systematic error interfering even
when any modelling or measurements errors are considered is explained and quantified for
two regularized reconstruction methods and several types of observed scenes. The propagation of
radiometric noise on data is singled out in a specific work, just like the impact of modeling errors
ensuing from an auto-characterization technique, allowing in-flight calibration of instrumental parameters.
The impact of the pollution of the interferometric data by the sun radiation on the remote sensing
of the ocean salinity is then studied. At last, the feasibility and the robustness of
full-polarization image reconstruction with regularized methods are proved.
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Submitted on : Thursday, July 28, 2005 - 11:36:02 AM
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Bruno Picard. Télédétection de la surface terrestre par un radiomètre imageur à synthèse d'ouverture : principes de mesure, traitement des données interférométriques et méthodes de reconstruction régularisées. Traitement du signal et de l'image. Université de Versailles-Saint Quentin en Yvelines, 2004. Français. ⟨tel-00009029v3⟩

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