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Utilité de l’image de cohérence du couple tandem (ERS-1/2) dans la délimitation et le calcul des dimensions des lacs et de la végétation dans la zone de Buzau en Roumanie

Abstract : In radar SAR interferometry (InSAR/DinSAR), a Tandem pair (ERS-1/2) is used for the realization of a DEM or the detection of deformations of a major event (e.g. earthquake) occurring between two acquisitions. The advantage of the Tandem pair is the time interval of 24 hours between the two captures. Generally, there is no temporal decorrelation considering the small difference in time between the acquisitions; that results in a good coherence. The coherence image is used indirectly in radar SAR interferometry (Synthetic Aperture Radar) as an indicator of the levels of confidence of the interferograms. It can be used in a direct way to identify and delimit the various movement zones which disturb the phase of the radar wave (in each pixel).This parameter reacts in several cases as an indicator of the unstable movements of surface. These movements, as for instance the wave-movement of surface water, disturb the phase. In this case, coherence is null and it is represented by a dark colour. On the other hand, the stable places, as in the case of urban space, preserve the phase and they are represented in light colour. However, this parameter serves as indicator and at the same time separator between the moving zones and the stable ones. The objective of this work is to show the utility and the effectiveness of the coherence image in the cartography of lakes and vegetation in a region at the Curvature of the Romanian Carpathians. We measured the surfaces and dimensions of the lakes based on the Tandem pair and made a comparison with the existing data and interpreted the results obtained: (i) the three lakes, located in the plain to the East and North-East of the Buzău town, clearly appear in the coherence image; (ii) regarding the vegetation, two test areas were picked in order to try to delimit and calculate their perimeters and surfaces. Using this image (coherence), one could distinguish the parts with vegetation in great movements due to the effects of the wind, therefore characterised by great heights. The lakes are well delimited, in particular when they are full, in the rain seasons. The coherence image thus makes it possible to delimit two natural elements in this area, the lakes and the vegetation.
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  • HAL Id : halshs-01141106, version 1


Kamel Hachemi, Abdelkader Abdellaoui, André Ozer, Florina Grecu, Mircea Cristian Visan. Utilité de l’image de cohérence du couple tandem (ERS-1/2) dans la délimitation et le calcul des dimensions des lacs et de la végétation dans la zone de Buzau en Roumanie. Teledetection, Editions des Archives Contemporaines / Editions scientifiques GB / Gordon and Breach Scientific Publishers, 2014, 11 (3), pp.373-384. ⟨halshs-01141106⟩



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