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Proposing Institution

German Aerospace Center DLR, Oberpfaffenhofen & TU München
Project Manager

Prof. Dr. Xiaoxiang Zhu
82234 Wessling
Static 3D city models are well established for many applications such as architecture, urbanplanning, navigation, tourism, and disaster management. The recent launches of very highresolution (VHR) Synthetic Aperture Radar (SAR) Earth observation satellites, like the GermanTerraSAR-X, provide for the first time the possibility to derive both shape and deformationparameters of urban infrastructure on a continuous basis. The proposal “4D City” is directedtowards 4D (space-time) urban infrastructure monitoring and visualization by fusion of multiplesensors: Differential Tomographic SAR (D-TomoSAR), stereo-optical images and LiDAR (LightDetection and Ranging). The different sensors complement to each other: stereo-optical datahave the best visual interpretability, LiDAR provides very accurate Digital Elevation Models(DEM), and D-TomoSAR as well as the related Persistent Scatterer Interferometry (PSI) are theonly methods to provide the dynamic component of buildings with up to millimeter accuracy, e.g.seasonal thermal dilation, structural deformation, or subsidence due to groundwater extractionor underground construction.Since VHR D-TomoSAR of urban infrastructure is a new research area, the development andimprovement of appropriate robust TomoSAR algorithms will be the first focus of the project.Second, data fusion for combining the strengths of different sensors will be developed both onthe geodetic and the semantic levels. Finally, a particular challenge will be the user specificvisualization of the 4D multi-sensor data showing the urban objects and their dynamic behavior.Visualization must handle spatially anisotropic data uncertainties and possibly incompletedynamic information. It may also integrate some of the data fusion steps. Different levels of userexpertise must be considered.The research envisioned in this proposal will lead to a new kind of city models for monitoringand visualization of the dynamics of urban infrastructure in a very high level of detail. Thechange or deformation of different parts of individual buildings will be accessible for differenttypes of users (geologists, civil engineers, decision makers, etc.) to support city monitoring andmanagement as well as risk assessment.

Impressum, Conny Wendler