A Study on the Extraction of DEM from Single SAR Image

摘要

SAR is a side-looking imaging mode and its image is very sensitive to the terrain shape. The little undulation of the terrain may induce the change of the image gray distribution and/or the texture characteristics. In this paper, the radarclinometry for extracting digital elevation from single SAR image is investigated, which is based on the shape-from-shading principle developed in computer vision, consists in estimating the geometric parameters of a ground, from its radiometry and more precisely from the backscattered intensity coming from a piece of imaged ground. Firstly, the approaches for generation of the digital elevation from the SAR image data are discussed. Secondly the method of radarclinometry will be briefly described. The elevation reconstruction relies on the Lambertian assumption for the terrain backscatter model. Then a single-line integral process is applied to calculate each pixel altitude, but it is still contaminated by noise. Finally the multi-line integral processing with various directions and the simulated annealing algorithm are respectively introduced to improve the single-line integral processing result. The presented experiment results promising in many geographic applications. This is an interesting technique of relief restoring, because it uses one single image only.