Extraction of DEM from single SAR based on radargrammetry

Topographic information is important in many geographic applications. Synthetic aperture radar (SAR) is a kind of imaging radar capable of producing high-resolution images in all weather and all-day conditions. But it is usually needs image pair or more images to generate DEM from SAR imagery, such as interferometric SAR (InSAR) and radargrammetry. The imaging conditions (look-angle, space baseline, for acquiring the image pair) sometimes are very difficult. SAR is a side-looking imaging mode and its image is very sensitive to the terrain shape. The 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 the earth elevation from only single SAR image is investigated, which is based on the shape-from-shading principle developed in computer vision. Firstly, the approaches for generation of the digital terrain elevation from the SAR image data are discussed. Secondly the method of radarclinometry is briefly described. The elevation reconstruction relies on a 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