为提高地基合成孔径雷达(GB-SAR)影像二维坐标到地方三维坐标转换的全局精度和可靠性,克服传统相似变换参数估计法的局限性,提出三维激光扫描数据辅助GB-SAR影像坐标三维变换方法。首先推导了相似变换参数估计法缩放因子的计算公式。分析结果表明相似变换法在目标处于不同相对高度条件下的计算精度不均匀,仅适用于距离雷达较远、范围较小的局部区域,并且相对于雷达中心的高度变化不能过于剧烈。由此提出利用三维激光扫描技术提供外部高程信息,依据GB-SAR成像几何投影原理,在投影面上完成点云和像元的匹配,实现GB-SAR影像坐标到地方三维坐标的变换计算。最后,结合GB-SAR隔河岩坝体高边坡变形监测试验,验证了该方法的有效性。研究成果有利于实际GB-SAR监测应用中对变形的三维解译和分析。
Abstract
In an attempt to improve the global accuracy and reliability of the transformation from 2D coordinates of GB-SAR images to local 3D coordinates, and to overcome the limitation of traditional similarity transformation parameter estimation method, we propose to employ 3D laser scanning data to assisting the transformation of GB-SAR image coordinates. Firstly we derive the formula for calculating the scaling factor of the similarity transformation parameter estimation method. Analysis results suggest that the similarity transformation method is only applicable to local areas far away from radar and small in range with no dramatic change of height relative to the radar center because the calculation precision is not uniform for targets with varying relative height. We propose to provide external elevation information by 3D laser scanning technology, and subsequently transform GB-SAR image coordinates to local 3D coordinates by matching of point clouds and pixels on projection plane according to the geometric projection principle of GB-SAR imaging. Finally, we verified the effectiveness of the method of transforming GB-SAR by deformation monitoring experiment on the high slope of Geheyan dam. The research result is conducive to the 3D interpretation and analysis of GB-SAR deformation monitoring.
关键词
地基合成孔径雷达影像 /
干涉测量 /
三维激光扫描 /
坐标转换 /
缩放因子
Key words
GB-SAR image /
interference measurement /
3D laser scanning /
coordinate transformation /
scaling factor
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基金
住房和城乡建设部科技计划项目(2016-K4-089);精密工程与工业测量国家测绘地理信息局重点实验室开放基金项目(PF2015-4,PF2015-1);苏州科技大学人才引进科研资助项目(331511202)
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