基于探地雷达杂波抑制与偏移成像的树木根系定位方法  

Tree-root Localization Method Based on Migration Imaging with Clutter Suppressed in Ground-penetrating Radar

作　　者：李光辉 徐汇 刘敏 LI Guanghui;XU Hui;LIU Min(School of Artificial Intelligence and Computer Science, Jiangnan University, Wuxi 214122, China)

机构地区：[1]江南大学人工智能与计算机学院,无锡214122

出　　处：《农业机械学报》2022年第3期206-214,共9页Transactions of the Chinese Society for Agricultural Machinery

基　　金：江苏省农业科技自主创新资金项目(CX(19)3087);无锡市国际科技研发合作项目(CZE02H1706)。

摘　　要：探地雷达在果树和古树名木养护管理领域具有广阔的应用前景。针对探地雷达采集的Bscan图像中杂波影响根系定位精度的问题,提出了基于鲁棒深度自动编码器(RDAE)、直接最小二乘法(DLS)和频率波数域偏移(FKM)相结合的树木根系定位方法。首先,通过RDAE将零点校正后的Bscan图像分解为表示杂波的低秩分量和表示根系目标回波的稀疏分量,保留稀疏分量完成杂波抑制;然后使用DLS拟合目标回波形成的双曲线估算土壤的相对介电常数;最后,根据土壤的相对介电常数计算得出偏移速度作为频率波数域偏移的输入进行偏移成像,获取根系的半径和深度信息从而完成根系定位。实验结果表明:RDAE方法在仿真和实测数据上的杂波抑制效果对比均值减法(MS)、奇异值分解(SVD)和鲁棒主成分分析(RPCA)有着更高的信杂比和改善因子,通过DLS估计的土壤相对介电常数均方根相对误差为3.84%,根系定位的最大半径相对误差和最大深度相对误差分别为8.5%、8.7%,能够完成根系位置标定,满足根系无损检测的需求,可为树木健康管理和移植提供决策支持。Ground-penetrating radar(GPR)has vast application potential for the root system testing of fruit trees and ancient trees.The clutter in GPR Bscan image often obscures the tree roots,thus reduces the accuracy of tree-root localization algorithm.A tree-root localization method combining robust deep autoencoder(RDAE),direct least square(DLS)and frequencywavenumber migration(FKM)was proposed.Firstly,after performing time-zero correction,a GPR Bscan image was decomposed into its low-rank and sparse components by RDAE.The low-rank component represented the clutter,and the sparse component represented the response of the tree roots.Secondly,the dielectric constant of soil was estimated by fitting the target echo’s hyperbolic curve with the direct least square method.Finally,the migration velocity was calculated according to the dielectric constant of soil,and then the migration velocity was taken as the input of frequencywave number migration to get the radius and depth information of the tree-root.Experimental results showed that compared with the common clutter suppressed methods,including mean subtraction(MS),singular value decomposition(SVD),and robust principal component analysis(RPCA),RDAE had a better visual effect and higher signal-to-clutter ratio and improvement factor on both numerical simulated data and real GPR data.The root-mean-square relative error(RMSRE)value of the estimated dielectric constant of soil was 3.84%.The maximum radius relative error and the maximum depth relative error were 8.5%and 8.7%,respectively.The proposed method can meet the practical requirements of the tree-root non-destructive testing and provide decision support for tree health management and transplantation.

关 键 词：树木 根系定位 探地雷达 偏移成像 鲁棒深度自动编码器 双曲线拟合 

分 类 号：S126[农业科学—农业基础科学] TN957.51[电子电信—信号与信息处理]