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摘要: 城市建筑区域叠掩、阴影严重,图像理解困难且干涉相位变化复杂紊乱,一直是InSAR处理的困难区域。SAR图像仿真能为图像理解和处理方法研究提供数据支撑,然而现有建筑区域SAR图像仿真方法大多无法获得具有相干性的干涉SAR图像对。该文提出了一种面向建筑区域的干涉SAR复图像对仿真方法,能够获得建筑的复数图像对、干涉相位图以及叠掩成分数目等信息,为城区干涉SAR处理及信息提取研究提供仿真数据支撑。同时,基于仿真中对相位变化规律的分析,提出叠掩区相位解缠时的基准确定方法,解决传统解缠方法面临的叠掩区域干涉相位不连续问题,进而反演建筑高程信息。最后,通过建模仿真结果与实际SAR图像和干涉相位的对比,验证了仿真方法的正确性,并对仿真及实际干涉相位进行解缠和高程反演处理,验证了该文高程反演方法的有效性。Abstract: The layover and shadow phenomenon is serious in urban areas, where the interferometric phase is complex and disordered and interpretation of an image is difficult. Therefore, it is always a hot and difficult problem for InSAR processing. SAR image simulation can provide data support for the study of image processing and understanding methods. However, most existing SAR image simulation methods for construction areas cannot obtain coherent interferometric SAR image pairs. This article proposes an InSAR simulation method for buildings. It can simulate complex images, interferograms, and the number of layover components of the construction areas. In addition, based on the analysis of the phase variation characteristics of the simulation, a reference determination method for the unwrapped phase in the layover area is proposed. It solves the problem of discontinuity of the interferometric phase in the construction areas, with which the traditional method of unwrapping cannot deal effectively. We compared the simulated results using the actual SAR images and interferometric phase and verified the correctness of our simulation method. Moreover, we carry out phase unwrapping and elevation inversion experiments using the simulated and real images and verified the effectiveness of our phase unwrapping method in applying the InSAR elevation inversion.
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表 1 TerraSAR参数及仿真参数
Table 1. Parameters of TerraSAR images and simulation
图像 参数 取值 TerraSAR
及仿真距离向分辨率(m) 0.4547 方位向分辨率(m) 0.1670 主图像下视角(°) 54.52 辅图像下视角(°) 54.49 仿真 图像大小(距离,方位) (500, 600) 主雷达位置(m) (0, 500160.3, –356368.6) 基线向量(m) (51.52, –188.1, –238.0) 相位噪声模型 标准差为π/4的高斯随机噪声 表 2 建筑物高程反演结果
Table 2. The elevation inversion results of the buildings
建筑序号 三维模型建筑
高度(m)仿真图像重建高度 真实图像重建高度 均值(m) 标准差(m) 均值(m) 标准差(m) 1 100.5 101.39 1.20 99.75 4.48 2 91.6 92.84 2.56 93.69 2.31 3 98.4 99.90 2.35 99.10 3.17 4 88.3 \ \ \ \ -
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