Advanced Methods For Building Height Extraction From High Resolution SAR Images

Synthetic Aperture Radar (SAR) is an active remote sensing system working in the microwave spectrum. It can be used for target observation and large-area imaging using multiple bands, multiple angles, and multiple polarizations. With the launch of the new and advanced space-borne high-resolution SAR systems, the research in the field of synthetic aperture radar technology developed rapidly. SAR has become one of the most important methods of the earth observation and remote sensing. Thus, it is of great practical importance to develop new high-resolution SAR image information extraction and interpretation technologies.Building height extraction from SAR images is of great significance in urban remote sensing applications. However, it is also a difficult problem in SAR image processing and interpretation, due to the side-looking imaging mechanism and backscattering characteristics of SAR system. They make the interpretation of building targets and the information extraction from SAR images of urban areas difficult. Therefore, it is necessary to carry out a systematic research approach for building height extraction from SAR image in urban areas. The in-depth analysis of SAR images reveals a rich source of information and characteristics, such as backscattering, phase, and spectrum. According to the different targets, the different scenes, and the available data, the most suitable and best methods for building height information extraction are to be determined. This can provide new ideas and more abundant research findings for extracting building heights effectively for3D building reconstruction applications.In order to extract building height information from SAR images, based on the principles of SAR imaging, we go into the basics of SAR/InSAR/TomoSAR and analyze the backscattering characteristic of buildings in SAR images. In this paper, based on the review of the domestic and foreign studies in this field, the study also analyses and induces various approaches. The main contents of the thesis are as follows:(1) Detailed analysis of backscattering characteristics of SAR and typical scattering mechanisms in urban area, especially regarding the double-bounce. A method for building height determination via radar backscattering characteristics is studied. The algorithm of retrieving double-bouncing points is given by experiments. A variety of model parameters and ground information is analyzed and tested. Its accuracy and reliability are verified by using space-borne high-resolution SAR data.(2) Extending and expanding the existing method of height inversion with InSAR, the new space-borne high-resolution interference data from the bi-static TerraSAR-X/TanDEM-X mission is used to obtain interferograms. By manually extracting the relevant information from the interferograms, the building height can be retrieved fast and simple, In addition, a detailed induction and summary of the problems, which impact building height acquisition with InSAR, are given.(3) Compressive sensing is applied to SAR tomography, making use of its advantage in the spectral analysis. Additionally, the echo signal reconstruction is studied, the principle of compressive sensing and of the measuring process is demonstrated, and a method using compressive sensing to solve a spectral analysis problem in SAR tomography is presented. Experiments are carried out using simulations and TerraSAR-X spotlight data, to verify the effectiveness and accuracy of the proposed method.