在地形起伏较大的山区用干涉SAR生成DEM时,合适的入射角是获取高精度DEM的重要参数之一.本文基于ENVISAT/ASAR多角度干涉雷达数据,SRTM 90米分辨率的DEM以及1:5万的数字化DEM数据,从定性和定量的角度比较和分析了干涉SAR在获取山区DEM时,入射角对DEM精度的具体影响.结果表明:对于ASAR的多入射角干涉雷达数据,在不同入射角条件下由于雷达叠掩和透视收缩的影响,获取的DEM精度差别很大,入射角带来的影响相当显著,比如IS2和IS4角度得到的DEM的精度差超过了6米.因此,在山区干涉SAR地形成图时,必须对入射角的大小进行严格的选择.

With the successful implementation of ERS-1/2tandem and SRTM projec,t InSAR hasbeenwildly used for topographicmapping; in addition, the new global topographicmission such as Tan DEM-X project is ongoing. In this paper, firstly, the impact of incidence angle on interferometric SAR DEM generation is detailed investigated from theoreticalviewpoin;t then, from the ENVISAT/ASAR multi-angle interferometric SAR data,the threeDEMs of IS2,IS3and IS4swath images are generated using EvInSAR software of EarthView; finally, the impact of layover and foreshortening on DEM accuracy atdifferent incidence angle are compared and analyzed from quantitative and qualitative viewpoints using SRTM DEM with90m horizontal resolution and digital topographic DEM with1∶50000scale. The results indicate tha:t (1) the impactof incidence angle onDEM generation is significantand large differences exist in the result DEMs due to radar layoverand foreshortening at different incidence angle. Forexample, the difference is over6m between the DEMs extracted from IS2and IS4swath images. So, the incidence anglemustbe strictly selectedwhen using In SAR for DEM generation in themountain area. (2) The decorrelation is significantwith the35-day tempora,l which is in prejudice of the over all DEM accuracy evaluation. If the datawith large incidence angle and no temporal decorrelation is obtained, the further study and analy siswillbe implemented from more generalquantitative and qualitative viewpoints.