# 3D Monitoring of Buildings Using TerraSAR-X InSAR, DInSAR and PolSAR Capacities
###### Abstract
[12] presents first-time DinSAR measurements of deformations of the Eiffel Tower, over a time period of some weeks, without deformation hypothesis. The polarimetric SAR (PolSAR) images raise the level of information on scattering processes, and thus can enhance the quality of urban classification schemes [13]. It has already been shown that it could help the information extraction ability for material scene in the observation area [14], or the information on the geometry of scatterers [15; 16]. PolSAR data have also been used in DInSAR applications to maximize the quality and number of pixels selected as reliable, by optimising the parameters used as selection criterion [17; 18]. In our paper, we propose to address building monitoring through these different techniques, but with additional constraints, which have not been dealt with in the literature up to now:  
* We do not want to use a priori information about the elevation or the evolution of the deformations through time. * We want to avoid spatial average, as far as possible to preserve the high resolution of the data. No selection of pixels is used, and polarimetric parameters are derived under the deterministic hypothesis. * Temporal stack can be used to make estimations more robust, when possible, both for InSAR and PolSAR modes. Another major challenge is the evaluation of the relevance of the traditional algorithm for this VHR images, and the precise assessment of the results. As pointed out also in [11], previous research using InSAR data on building deformation was analyzed from a qualitative viewpoint using only field survey results; and before the above mentioned work, no quantitative analyses have been performed comparing the InSAR accuracy for monitoring buildings with in situ leveling records. In order to have a validation as reliable as possible of the different products obtained, we selected a site well mastered. The chosen site of interest is the neighborhood around the Eiffel Tower called Front de Seine. Besides the mythic Eiffel Tower, three buildings are considered in the interferometry study and two others are added specifically for the polarimetric study. Information about the buildings material, 3D maps of the buildings and weather data have been collected. Finally, in situ measurements were used to validate the Eiffel Tower deformations. Thus, Section 2 presents the whole dataset. The studied buildings are also presented, as well as the meteorological causes of the daily deformations of these buildings and their respective influence on the structures. Finally, conventions used in this paper to handle the different observables are described. The following sections are dedicated to each of the three analyzed modes. The measure of the height using across-track InSAR techniques is detailed in Section 3. Section 4 deals with the DInSAR deformation measurement based on the previously estimated height. The estimated deformations are validated against weather data and in situ measurements. The accuracy limit caused by atmospheric effects is discussed. Finally, Section 5 addresses the benefit of the polarimetric information, and conclusions are summarized in the last section.