Tomographic Urban Mapping and Object Reconstruction Using TerraSAR-X Spotlight Data Stacks

Speaker: Dr. Xiaoxiang Zhu (DLR)

Time and Date: 10:00-11:15, Jan. 7, 2014

Place: Room 1101, East Guanghua Building, Handan Campus

 

 

Abstract

A conventional spaceborne or airborne Synthetic Aperture Radar (SAR) maps the three-dimensional (3-D) reflectivity distribution of a scene to be imaged into the 2-D azimuth-range (x-r) plane. This can be seen as a projection along the third radar coordinate, elevation (s). x, r, and s form an orthogonal coordinate system specific to the particular SAR imaging geometry. This projection particularly handicaps the interpretation of SAR images of (i) volumetric scatterers and (ii) of urban areas and man-made objects, i.e. objects with constructive elements oriented at steeper angles than the local incidence angle. SAR tomography (TomoSAR) extends the synthetic aperture principle of SAR into the elevation direction for 3-D imaging. It uses acquisitions from slightly different viewing angles (the elevation aperture) to reconstruct for every azimuth-range (x-r) pixel the reflectivity function along the elevation direction s. It is essentially a spectral analysis problem.

 

We work with TerraSAR-X high resolution spotlight data. In this seminar, the potential of the new class of VHR space-borne SAR systems for tomographic reconstruction in urban environment will be demonstrated, in particularly: The first 3-D of an entire urban area (incl. its radar reflectivity) with very high level of detail from space-borne SAR data by TomoSAR will be presented; Examples with promising layover separation in urban area will be shown; Due to the side-looking geometry of SAR, a single stack of SAR images only provides information on one side of a building. To serve the function of urban structure monitoring, TomoSAR results of multiple stacks from different view angles are fused together to provide us with a shadow-free point cloud with high degree of coverage over the entire urban area; In order to provide a high quality spatio-temporal 4D city model, object reconstruction from these TomoSAR point clouds is emergent. A 3D view of the reconstructed façades over a test building and over larger area using TomoSAR point clouds is exemplified.

 

 

Biography

Xiaoxiang Zhu received the Master (M.Sc.) degree, her doctor of engineering (Dr.-Ing.) degree and Habilitation from Technical University of Munich (TUM), Germany, in 2008, 2011 and 2013, respectively. Since May 2011, she is a scientist with the Remote Sensing Technology Institute at the German Aerospace Center (DLR), Oberpfaffenhofen, where she is the head of the Team Signal Analysis and with the Chair of Remote Sensing Technology at TUM. Since September 2013, she is also a Helmholtz Young Investigator Group Leader. Her main research interests are: advanced InSAR techniques such as high dimensional tomographic SAR imaging and SqueeSAR; computer vision in remote sensing including object reconstruction and multi-dimensional data visualization; and modern signal processing, including innovative algorithms such as compressive sensing and sparse reconstruction, with applications in the field of remote sensing such as multi/hyperspectral image analysis. She is giving courses in signal processing, estimation theory and remote sensing. Dr. Zhu is the developer of the DLR's Tomographic SAR Processing System ─ Tomo-GENESIS. She is author of more than 80 scientific publications, among them 39 full-paper peer-reviewed papers and 6 paper awards.