Maximum bathymetric depth estimation for airborne LiDAR without in-situ sampling
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摘要: 浅水区域的地形测量数据能够为海洋资源开发、水资源调查管理等提供基础的数据支撑,一直是海洋测绘等领域的研究热点。机载LiDAR测深(Airborne LiDAR Bathymetry,ALB)是一种高精度、高效率、机动性强的一种测量技术,特别适用于浅水区域的地形测量。针对机载激光最大测深估算依赖传统现场采样法(如赛齐盘透明度测量)效率低、成本高的问题,论文提出一种联合卫星遥感水色数据产品与波形建模的无现场采样最大测深估算方法。通过获取NASA Ocean Color的Kd(490)产品反演得到532 nm波段漫衰减系数,结合激光测深回波信号的物理模型,得到水面、水体、水底以及噪声的回波叠加波形,并利用峰值探测算法实现最大测深自动化判定。以山东省青岛市胶州湾与青海省德令哈市托素湖为实验区域,实验结果表明利用所提方法估算的最大测深估算偏差均不超过0.4 m,相对误差保持在5%以内,验证了方法的有效性。本文所提方法无需现场采样,相较于传统方法以卫星遥感水色数据产品代替现场透明度测量,不仅显著降低了机载LiDAR测深外业测量成本,还能够为浅水区测绘与水资源调查提供高效的技术支撑。Abstract: Terrain measurement data in shallow water areas provide essential support for marine resource development and water resource investigation and management, making them a focal point in marine surveying and related fields. Airborne LiDAR Bathymetry (ALB) is a high-precision, high-efficiency, and highly mobile measurement technology particularly suited for topographic surveys in shallow water regions. To address the inefficiencies and high costs associated with traditional on-site sampling methods ( Secchi disk transparency measurements) for estimating maximum bathymetric depth using airborne LiDAR, this study proposes a novel method for maximum depth estimation without on-site sampling, integrating satellite remote sensing water color data products with waveform modeling. By retrieving the diffuse attenuation coefficient at 532 nm through inversion of NASA Ocean Color’s Kd(490) product and combining it with a physical model of LiDAR bathymetric echo signals, the method constructs a superimposed waveform model incorporating contributions from the water surface, water column, seabed, and noise. A peak detection algorithm is then employed to automate maximum depth determination. Experimental results from Jiaozhou Bay in Qingdao City, Shandong Province, and Tuosu Lake in Delingha City, Qinghai Province, demonstrate that the proposed method achieves maximum depth estimation with deviations not exceeding 0.4 m and relative errors within 5%, validating its effectiveness. By replacing on-site transparency measurements with satellite remote sensing water color data products, the proposed method eliminates the need for field sampling, significantly reducing the operational costs of airborne LiDAR bathymetry while providing efficient technical support for shallow water mapping and water resource investigations.
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图 3 青岛胶州湾机载LiDAR测深实验概况
a. 测区地理位置(审图号:GS(2019)3333号);b. 机载测深LiDAR;c. 现场水质情况;d. 无人机平台;e. 青岛胶州湾沿岸地理概况
Fig. 3 Overview of the airborne LiDAR bathymetry experiment in Jiaozhou Bay, Qingdao
a. Geographical location of the study area (Map Approval Number: GS(2019)3333); b. airborne bathymetric LiDAR; c. on-site water quality conditions; d. UAV platform; e. geographical overview of the Jiaozhou Bay coastline
图 4 青海托素湖机载LiDAR测深实验概况
a. 测区地理位置(审图号:GS(2019)3333号);b. 现场飞行照片;c. 青海托素湖卫星影像;d. 现场水质情况
Fig. 4 Overview of the airborne LiDAR bathymetry experiment in Tosu Lake, Qinghai
a. Geographical location of the study area (Map Approval Number: GS(2019)3333); b. on-site flight photos; c. satellite imagery of Tosu Lake, Qinghai; d. on-site water quality conditions
表 1 建模中部分系统参数和环境参数
Tab. 1 System parameters and environmental parameters in modeling
系统参数 数值 环境参数 数值 激光波长λ 532 nm 大气双程损失${T^2_{{\mathrm{atm}}}} $ 0.9 脉冲宽度T0 5 ns 水面粗糙度r 0.1 航高H 130 m 水体折射率nw 1.33 入射角θ 20° 水底反照率Rb 0.12 发射光学效率ƞe 0.9 镜面反射系数ks 0.98 接收光学效率ƞR 0.58 漫反射系数kd 0.02 噪声标准差 1.1 漫衰减系数Kd(532) 0.197 表 2 实验真实系统参数和环境参数
Tab. 2 Actual system and environmental parameters used in the experiment
测区 航高/m Kd(532) 青岛胶州湾 130 0.19 青海托素湖 160 0.15 表 3 建模中部分系统参数和环境参数
Tab. 3 System Parameters and Environmental Parameters in Modeling
测区 实测最大测深/m 估算最大测深/m 深度差值/m 青岛胶州湾 7.90 8.3 0.40 青海托素湖 8.45 8.7 0.25 -
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