Abstract: For the direct and indirect ortho-rectification of SAR image based on DEM, this paper gives the difference analysis for the theory, steps, correction effect and applicability. Moreover, it makes a comparison for the correction accuracy are based on the orthographic corrected high resolution satellite image. Experimental results illustrate that although the two methods are based on the same model, the start points are different, the steps and computational complexities as well as the correction effects are also different. But the correction accuracy difference between the two methods is very small. Both can meet the demand of the correction accuracy and the appropriate method should be chosen according to actual situation.

Key words: Synthetic Aperture Radar（SAR）, Digital Elevation Model（DEM）, direct ortho-rectification, indirect ortho-rectification

摘要： 对基于DEM的SAR影像直接校正与间接校正方法的原理、步骤、校正效果与适用性进行了比较，并利用正射校正过的高精度光学卫星影像作为基准影像，对两种方法的校正精度进行验证与比较。分析表明，两种方法所采用的校正模型相同，但出发点不同，校正步骤与复杂度也不同，最终校正效果也不一样，但精度没有差很多，都能满足常规SAR正射校正精度需求，在实际应用中需要根据实际情况选择合适的方法。

关键词: 合成孔径雷达（SAR）, 数字高程模型（DEM）, 直接正射校正, 间接正射校正