F. Chaabane

École Supérieure des Communications de Tunis, L’Ariana, Ariana, Tunisia

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Publications (20)3.47 Total impact

  • S. Rejichi, F. Chaabane
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    ABSTRACT: Satellite Image Time Series (SITS) are a very useful source of information for geoscientists especially for land cover monitoring. In this paper a new temporal classification approach for High Resolution (HR) SITS is proposed. It suggests a Bayesian combination between a pixel and a region, SVM (Support Vector Machine) based techniques where SVM is considered as a probabilistic classifier. RBF (Radial Basis Function) based SVM kernel is used to classify pixel evolution while a graph based SVM kernel is considered to analyze region temporal behavior.
    Geoscience and Remote Sensing Symposium (IGARSS), 2012 IEEE International; 01/2012
  • S. Réjichi, F. Chaâbane
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    ABSTRACT: This paper proposes a new HR spatio-temporal vegetation classification approach based on SVM. A multi-band SVM approach is first applied on satellite images time series then a graph based SVM algorithm is used for temporal analysis.
    Proc SPIE 10/2011;
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    ABSTRACT: Multitemporal SAR images are a very useful source of information for geophysicists, especially for change monitoring. In this paper, a new SAR change detection and monitoring approach is proposed through the analysis of a time series of SAR images covering the same region. The first contribution of this work is the SAR filtering preprocessing step using an extension of the spatial NL-means filter to the temporal domain. Then, the Rayleigh Kullback Leibler measure is used to detect the changes between a reference image and each SAR image. This leads to the second contribution which consists on a temporal classification based on changes images and describing the temporal behaviour of the changing regions.
    Analysis of Multi-temporal Remote Sensing Images (Multi-Temp), 2011 6th International Workshop on the; 08/2011
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    ABSTRACT: Vegetation spatial distribution is an important part in any study implying biodiversity and, more generally, landscape management. Here the problem is exemplified by studies aimed at providing the vegetation distribution needed for simulating wildfire propagation.
    Space Technology (ICST), 2011 2nd International Conference on; 01/2011
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    S. Réjichi, F. Chaabane, F. Tupin, I. Bloch
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    ABSTRACT: This paper proposes a new morphological filter for SAR interferograms. It is based on a modified version of alternate sequential filters with reconstruction (MASF), in which the structuring elements are adaptively defined according to the fringe directions. This provides a good fidelity to the fringe information while efficiently removing noise. Another feature of the proposed approach is to apply the filter on the original interferogram and on shifted version, to overcome the wrapping of the phase, and to combine the two results. The proposed filtering technique is then tested on both simulated and real data with different levels of noise. It is also compared to previous techniques according to simplicity and noise reduction.
    Geoscience and Remote Sensing Symposium (IGARSS), 2010 IEEE International; 08/2010
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    ABSTRACT: In the literature, several works are led around the radar images especially the detection of the cartographic objects, the D reconstruction and the change detection. Concerning this last application, several techniques compete to ensure the best possible result. In this paper, we aim first at developing an automatic detection procedure to compare between similarity measures. Then we propose a change detection technique based on the fusion of two similarity measures. The first one is the Contrast (C) measure [1] and the second one is the Rayleigh Distribution Ratio (RDR) measure [2]. The proposed method has been validated on simulated data and then applied on three radar images.
    IEEE International Geoscience & Remote Sensing Symposium, IGARSS 2010, July 25-30, 2010, Honolulu, Hawaii, USA, Proceedings; 01/2010
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    S. Hachicha, F. Chaabane
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    ABSTRACT: Synthetic Aperture Radar (SAR) data enables direct observation of land surface at repetitive intervals and therefore allows temporal detection and monitoring of land changes. However, the problem of radar automatic change detection is made more difficult, mainly with the presence of speckle noise. This paper presents a new method for SAR image change detection using the Dezert-Smarandache Theory (DSmT). First, a Gamma distribution function is used to characterize globally the radar texture data and allows mass assignment throw Kullback-Leibler distance. Then, local pixel measurements are introduced to refine the mass attribution and take into account the context information. Finally, DSmT is carried out by comparing the modelling results between temporal images. The originality of the proposed method is on the one hand, the use of DSmT which achieve a plausible and paradoxical reasoning comparing to classical Dempster-Shafer Theory (DST). On the other hand, the given approach characterizes the radar texture data with a Gamma distribution which allows a better representation of the speckle. The radar texture is being usually modeled by a Gaussian model in previous DST and DSmT fusion works.
    Image Processing (ICIP), 2009 16th IEEE International Conference on; 12/2009
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    ABSTRACT: This paper presents an application of DInSAR techniques for the assessment of ground subsidences around Tunis City. A longterm analysis using two interferometric techniques were carried out to attempt reliable measurements. In this work, some aspects of interferometric processing softwares are reviewed and possible improvements are proposed in order to get better results. The convergence of the two different interferometric techniques done simultaneously and independently confirms results accuracy.
    Geoscience and Remote Sensing Symposium,2009 IEEE International,IGARSS 2009; 08/2009
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    ABSTRACT: Permanent scatterers (PS) approach allows the identification of radar targets not affected by decorrelation noise then suitable for reliable SAR interferometric measurements. This paper introduces a new technique allowing the selection of stable scatterers based on adaptative SVA (Spatially Variant Apodization) filtering. Indeed, SVA filters identify SAR pixels with strong reflectivity (maximum of the mainlobe) over a long temporal series of interferometric SAR images which is the main feature of Permanent Scatterers pixels. A comparison between PS candidates pixels and selected SVA pixels is discussed in this study.
    Geoscience and Remote Sensing Symposium,2009 IEEE International,IGARSS 2009; 08/2009
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    F. Chaabane
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    ABSTRACT: Topographic profile reconstruction and ground surface change detection are actually being measured by SAR and differential SAR interferometry. The deal is how topography is estimated from interferometry especially the relative sensitivity of measured radar phase to topography and changes in topography. The objective of this paper is to combine several DEM (Digital Elevation Model) resulting from different interferometric processing by taking into account the coherence information in order to improve the topographic profile accuracy. For that purpose different conjunctive operators are used in data fusion processing. The resulted digital elevation models are evaluated using Mean Square Error (MSE) according to a local reference DEM.
    Geoscience and Remote Sensing Symposium, 2008. IGARSS 2008. IEEE International; 08/2008
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    M. Sellami, F. Chaabane, C. Fetita
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    ABSTRACT: This paper presents an unsupervised segmentation method applied to multispectral satellite images especially SPOT images. The main objective of this work is to combine spectral and contextual information in order to extract the most important cartographic regions. We choose a mathematical morphology context. Previous morphological works are usually interested in one type of land covering area. The proposed technique globalizes the problem by considering all the important regions to perform complete and automatic multispectral satellite images cartography.
    Geoscience and Remote Sensing Symposium, 2008. IGARSS 2008. IEEE International; 08/2008
  • A. Shabou, F. Tupin, F. Chaabane
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    ABSTRACT: With the development of remotely-sensed multisensor satellites like Pleiades Cosmo-Skymed that have the particularity of providing both SAR and optic data, new techniques in image processing are needed. These techniques must take into account the complementarities and differences in nature of these data. A preliminary operation for advanced techniques that use multisensor images such as fusion, classification, etc. is registration. In the case of SAR and optic data, we can do automatic registration if we exactly know the sensor parameters and have a digital terrain model (DTM) or a digital elevation model (DEM) at our disposal. If we do not have an exact knowledge of these parameters, the registration becomes difficult. Another approach to achieve the automatic registration which does not need sensor parameters will rely on comparison measures between both data. In this paper, we present a comparison of several similarity measures between multisensor SAR and optic images used in matching algorithms. An evaluation of these measures for synthetic data based on their distributions is given. Then results on real images are analyzed.
    Geoscience and Remote Sensing Symposium, 2007. IGARSS 2007. IEEE International; 08/2007
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    ABSTRACT: Tropospheric inhomogeneities can form a major error source in differential synthetic aperture radar interferometry measurements, which are used in slow-deformation monitoring. Indeed, variations of atmospheric conditions between two radar acquisitions produce variations in the signal path of two images and, thus, additional fringes on differential interferograms. These effects have a strong influence on interferograms and must be compensated to obtain reliable deformation measurements. This paper presents a methodological approach to reduce at both global and local scales tropospheric contributions directly from differential interferograms. It first requires refined knowledge of the stable scatterers that can only be obtained from the analysis of a large population of multitemporal interferograms. The correction of global-scale atmospheric contribution exploits the correlation between phase and topography. The correction of local artifacts is based on the correlation between interferograms containing one common acquisition. This technique is validated on a database of 81 differential interferograms covering the Gulf of Corinth (Greece) and used to improve the measurements of ground deformation compared to global positioning system measurements
    IEEE Transactions on Geoscience and Remote Sensing 07/2007; · 3.47 Impact Factor
  • IEEE T. Geoscience and Remote Sensing. 01/2007; 45:1605-1615.
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    F. Chaabane, F. Tupin, H. Maitre
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    ABSTRACT: Many are the examples of application of SAR and differential SAR interferometry for topographic mapping and ground deformation monitoring. However, on repeat pass geometry, the performances of these two techniques are limited by the loss of correlation (coherence) between the two radar acquisitions. The lack of coherence causes an additional noise thus a poor estimate of the interferometric phase. The disturbances can be due either to surface changes because of long period cover (temporal decorrelation) or to a too large baseline (spatial decorrelation). In this paper, we propose an empirical model for the estimate of coherence considering separately these two sources of disturbances. Starting from the observations of experimental data, we study the behaviour of coherence according to baseline and period cover in order to express the two terms of correlation. A number of 170 multi temporal and multi baseline differential interferograms covering the same region is used to validate the proposed model.
    Proc SPIE 10/2005;
  • F. Chaabane, F. Tupin, H. Maitre
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    ABSTRACT: SAR and differential SAR interferometry are operational tools for monitoring surface deformation and topographic profile reconstruction. However, they still have limitations due to temporal and geometric decorrelation. These disturbances strongly compromise the accuracy of the results, but reliable measurements can be obtained over a large multitemporal population of interferograms. In this paper we propose a new algorithm for monitoring temporal evolution of ground surface using several interferograms covering ground movements over a long period of time. It is based on a statistical approach with hypothesis test. The objective of multiple interferograms elevation retrieval is to deal with noisy data. Another important advantage of the multiple image processing is that all baselines (small or large) are considered. The method described in this paper can he applied in both SAR and differential SAR interferometry context. We chose to study the SAR interferometry case
    Geoscience and Remote Sensing Symposium, 2004. IGARSS '04. Proceedings. 2004 IEEE International; 10/2004
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    ABSTRACT: The presence of tropospheric contributions in SAR (Synthetic Aperture Radar) interferograms represents the main limit for the detection of vertical movements. The capability of correctly removing of tropospheric effects from the interferograms requires first a refined knowledge of the permanent scatterers of the area that can be obtained only through the analysis of a large population of interferograms. For that, 81 differential interferograms of the Gulf of Corinth (Greece) were produced on three different tracks, covering variable time spans (1day to 7.42 years) in the period 1992-1999. Both the 1992 Ms=5.9 Galaxidi earthquake and the 1995 Ms=6.2 Aigion event were covered by the data. A methodological approach was developped to reduce at both global and local scales the tropospheric contributions in the interferograms. This processing was applied, for each track, to all the calculated interferograms in six main steps. First, using all available interferograms, a coherence map of the area is produced to identify the permanent scatterers of the region. Second, the interferograms are filtered to reduce the noise and then masked by a collective coherence map where the coherence is poor and therefore the phase information lost. Third, assuming a horizontally homogeneous troposphere model, a linear correlation is estimated between the phase value of the most coherent pixels and their elevation; the obtained models are validated using the Bellman-Ford algorithm which detects any false estimation with respect to the others. Fourth, the interferograms are then unwrapped to remove the phase ambiguity and, fifth, a small-scale correction is performed. Comparing all the interferograms containing a common image, the common local phase anomalies are considered to be associated to that image and subsequently substracted from the interested interferograms. Finally, the corrected interferograms are stacked and averaged to reduce the high-frequency noise still present after the processing and to retrieve a smoothed deformation field related to the 1992 and 1995 earthquakes, expected to be smooth and provided by the offshore location of the ruptured faults. We compared the results obtained before and after the tropospheric corrections to detect the changes in the level of noise. The cleaned deformation field related to the Aigion earthquake concerns a N-S 16 km wide by E-W 28 km long band, reaching the maximum value of ~250 +/- 9 mm on Psaromita cape, a limestone mesozoic platform located on the northern side of the gulf, in front of the town of Aigion. The comparison between each corrected interferogram and the average deformation map reveals that, within the uncertainty of our displacement map (9 mm), no postseismic deformation is observed in the data in the period 1995-1999.
    03/2003; -1:7154.
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    ABSTRACT: The presence of atmospheric contributions in SAR interferograms represents the main limit for the detection of ground deformation movements. This paper presents a methodological approach to reduce at both global and local scales the tropospheric contributions in the interferograms. It first requires the refined knowledge of the permanent scatterers that can only be obtained from the analysis of a large population of interferograms. The correction of global scale atmospheric contribution exploits the correlation between phase and topography and the correction of local artefacts is based on correlation between interferograms containing one common acquisition.
    Geoscience and Remote Sensing Symposium, 2003. IGARSS '03. Proceedings. 2003 IEEE International; 02/2003
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    ABSTRACT: - L'aspect différentiel des données interférométriques est à l'origine du caractère multitemporel des images manipulées. Dans cet article, nous proposons une méthode de correction des effets atmosphériques en interférométrie différentielle fondée sur cette propriété. L'approche développée commence par sélectionner les pixels les plus cohérents et les plus stables dans le temps en s'appuyant sur la corrélation des effets atmosphériques avec la topographie. L'exploitation de ces pixels nous permet de retrouver un modèle atmosphérique pour chaque interférogramme. Ensuite, les relations existant entre les différents couples interférométriques sont utilisées pour valider les modèles d'atmosphère obtenus. La diversité des données interférométriques et leur répartition dans le temps fixent la robustesse de cette méthode.
    19° Colloque sur le traitement du signal et des images, 2003 ; p. 222-225.
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    ABSTRACT: We present here the correction of tropospheric effects in order to improve deformation mesurements when a dataset of muti-temporal interferograms is available. This method proceeds in two main steps. The first step is the estimation of global tropospheric effects. This is done two phases: First, a subset of very coherent pixels is identified using correlation between the phase value and topography. These pixels allow the computation of a global tropospheric model for each interferogram. Secondly, a cross validation of the models is applied using the entire multi-temporal database. Since multiple interferograms are available, a method can be conceived for the validation of tropospheric models using triplet of interferometric pairs containing one common acquisition. Indeed, it can be shown that an algebric relationship between parameters of the tropospheric models exists. The second step is the estimation of local tropospheric effects. We improve by the way a methodology based on correlation between interferograms containing one common acquisition. The modeled tropospheric effects are then removed from each interferogram. This technique was tested on a database of 81 differential interferograms of the Gulf of Corinth and used to improve the measurement of the ground deformation compared to GPS mesurements.