UAV-based mapping of nearshore bathymetry over broad areas
UAV-based mapping of nearshore bathymetry over broad areas
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基于无人机的大面积近岸测深测绘
DOI：
10.1080/21664250.2020.1747766
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发表时间：
2020
影响因子：
2.4
通讯作者：
Matsuba Yoshinao
中科院分区：
文献类型：
--
作者：
Tsukada Fumiya;Shimozono Takenori;Matsuba Yoshinao
本文开发了一种基于无人机（UAV）的近岸测深测绘方法。该方法基于根据无人机获得的海面视频估计的波速和频率的线性色散关系进行测深估计。在测深估计之前，应用包括自动帧校正在内的图像处理将视频转换为连续的正射影像。该方法通过滤波过程选择性地分析源自浪涌的信号。涌浪的波速是根据互相关分析从两个位置的信号时滞来估计的。沿着跨岸部分估计测深，然后通过沿着海岸线重复该估计来获得二维测深。通过将此方法应用于在 50 ~ 150 米高度悬停约 5 分钟获得的视频，可以以约 0.5 m 的精度估计沿海岸线约 1 公里长度区域的测深。即使在防波堤分离的海岸上，该方法也能表现良好，并且精度不会显着下降。此外，我们研究了该方法在各种条件下的适用性，结果表明在多云的天空下估计精度可能会较差。
In this paper, an unmanned aerial vehicle (UAV)-based method of nearshore bathymetry mapping is developed. The method is based on the bathymetry estimation from a linear dispersion relationship with wave celerity and frequency estimated from a sea-surface video obtained by the UAV. Prior to the bathymetry estimation, image processes including automatic frame rectification are applied to convert the video into sequential orthoimages. The method selectively analyzes the signals originated from swells through filtering processes. Wave celerity of swells is estimated from a time lag of the signals at two locations based on cross-correlation analysis. Bathymetry is estimated along the cross-shore section, then a two-dimensional bathymetry is obtained by repeating this estimation along the shoreline. By applying this method to a video obtained by ~5-min hovering at 50 ~ 150-m altitude, bathymetry over an area of ~1-km length along the shoreline can be estimated with an accuracy of ~ 0.5 m. The method performs well even on a coast with detached breakwaters without significant decrease in accuracy. Furthermore, we investigate the applicability of the method under various conditions, and the results suggest that the estimation accuracy can be worse under cloudy skies.