摘要
过去众多阐述INSAR或DINSAR的论文中 ,往往采用平行射线近似处理方法 ,舍去干涉图中随距离位置不同形成的相位成分 ,从而大大简化了后续的推导工作。但对于星载雷达而言 ,不能忽略微小项。通过平地相位去除处理 ,建立了严密的DINSAR用于形变量提取的数学模型。采用平行射线近似处理方法 ,即使通过类似的平地相位去除处理 ,尽管可以得到同样的数学表达式 ,但无法表达干涉相位准确的物理意义 ,论证也不严密。为此 ,对当前几乎已成定论的推论进行了修正 ,并进一步推出 :如果观测期间没有发生形变 ,经过平地相位去除的干涉相位的比值与基线垂直分量的比值相等 。
A parallel ray approximation has been used to discuss the mathematic model of INSAR and DINSAR in many papers,with ignoring a small term expressing the phase part relative to the distance in the line of sight(range) and thus making it much easier for deduction.Unfortunately,after analyzing the effects of the term neglected,we draw a conclusion,it is an appropriate approach to neglect the small term only for an aircraft system but a spacecraft.Furthermore,we remove a term that would exist even in the absence of topography on a spherical earth from the interferogram phase,i.e. to flat earth,and deduce the important equation strictly,which shows how to obtain offset vectors from 3 Radar images without the 'true' values for the off nadir angle θ to each point in the image.If the parallel ray approximation is adopted,in spite of that,we can get the same mathematic formula in the way of 'flat earth',but the expression may be in no physical sense,i.e. the phase part relative with the distance in the line of sight(range) and the logic of the deduction is poor.In this paper,a revision conclusion is proposed:only if the parallel components are large enough, the above viewpoint is valid.Moreover, the ratio of the flattened interferogram phase is equal to the ratio of the perpendicular components of the baseline,independently of the topography.
出处
《大地测量与地球动力学》
CSCD
2003年第2期88-91,共4页
Journal of Geodesy and Geodynamics
基金
湖北省青年杰出人才基金项目 ( 2 0 0 2AC0 11)
武汉大学创新项目
