Tomographic SAR 3D Imaging Method Based on Geometry and Polarization Joint Constraints
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摘要: 层析合成孔径雷达(TomoSAR)是城市建筑物三维重建的重要技术。现有方法虽通过引入几何约束提升了成像质量,并在多极化条件下发展为极化层析SAR(PolTomoSAR),但仍面临复杂建筑结构下几何信息依赖性强、极化模型不完善等问题。为此,该文提出一种几何与极化联合约束的TomoSAR三维成像方法,融合建筑几何结构与Pauli极化相似度信息,结合极化相干最优处理及概率密度约束,显著提升点云成像质量。实验基于机载Ku波段4通道阵列苏州实测数据,结果表明所提方法在成像精度与完整性方面均优于现有方法,验证了其有效性与优越性。
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关键词:
- 极化层析合成孔径雷达 /
- 几何约束 /
- 极化相似度 /
- 三维重建 /
- 点云
Abstract: Tomographic Synthetic Aperture Radar (TomoSAR) is a key technique for 3D reconstruction of urban buildings. Although existing methods improve imaging quality by incorporating geometric constraints and have evolved into Polarimetric TomoSAR (PolTomoSAR) with multi-polarization capabilities, challenges remain in handling complex structures due to heavy reliance on geometric accuracy and limitations in polarization modeling. To address these issues, this paper proposes a novel TomoSAR 3D imaging method based on joint geometric and polarimetric constraints. The approach integrates building geometry with Pauli scattering similarity and incorporates polarization coherence optimization and probability density-based constraints to significantly enhance point cloud quality. Experiments using airborne Ku-band multi-channel SAR data over Suzhou, China, demonstrate the superiority and effectiveness of the proposed method in both accuracy and completeness of 3D reconstruction. -
1 约束的压缩感知三维成像流程
1. Constrained CS 3D imaging process
初始化:残差$ {r}_{0}={\boldsymbol{y}} $,y为观测向量,索引集$ S= \varnothing $,稀疏度
$ K=n $,当前解$ {x}_{0}=0 $。步骤1:选择约束后与当前残差$ {r}_{k-1} $最相关的观测矩阵元素, $ {j}_{k}=\arg {\max }_{j}|{\boldsymbol{\phi}} _{j}^{{\mathrm{T}}}{r}_{k-1}f\left(\theta \right)| $ 步骤2:将选中的索引$ {j}_{k} $添加到索引集S中,$ {S}_{k}={S}_{k-1}\cup\left\{{j}_{k}\right\} $ 步骤3:最小二乘法求解系数向量:
$ {{\boldsymbol{x}}}_{k}=\arg {\min }_{x}\|{\boldsymbol{y}}-{A}_{s}x{\|}_{2} $即$ {{\boldsymbol{x}}}_{k}={\left({\boldsymbol{A}}_{s}^{{\mathrm{T}}}{{\boldsymbol{A}}}_{s}\right)}^{-1}{\boldsymbol{A}}_{s}^{{\mathrm{T}}}{\boldsymbol{y}} $ 步骤4:更新残差:$ {r}_{k}={\boldsymbol{y}}-{{\boldsymbol{A}}}_{s}{{\boldsymbol{x}}}_{k} $ 终止条件:(1) 当残差小于预设阈值:$ \|{r}_{j}{\|}_{2} < \epsilon $ (2) 达到设定的稀疏度:$ k=K $。 表 1 无人机载TomoSAR与飞行参数
Table 1. UAV TomoSAR and flight parameters
参数 指标 SAR类型 阵列 频段 Ku波段 飞行高度 400 m 带宽 1200 MHz 轨道/阵列数量 4 中心下视角 45° 平均基线间隔 17.8 cm 极化通道 HH, HV, VH, VV 表 2 点云质量定量评价参数与结果
Table 2. Point cloud quality quantitative evaluation parameters and results
成像方法 RMSE 点云完整度 无约束三维点云 3.4827 1.2966 几何与极化联合约束三维点云 2.1240 0.8800 仅几何约束三维点云 2.9644 0.7155 谱估计三维点云 3.6703 1.6566 -
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