3D Ocean Water Wave Surface Analysis on Airborne LiDAR Bathymetric Point Clouds

Abstract

Water wave monitoring is a vital issue for coastal research and plays a key role in geomorphological changes, erosion and sediment transportation, coastal hazards, risk assessment, and decision making. However, despite missing data and the difficulty of capturing the data of nearshore fieldwork, the analysis of water wave surface parameters is still able to be discussed. In this paper, we propose a novel approach for accurate detection and analysis of water wave surface from Airborne LiDAR Bathymetry (ALB) large-scale point clouds data. In our proposed method we combined the modified Density-Based Spatial Clustering of Applications with Noise (DBSCAN) clustering method with a connectivity constraint and a multi-level analysis of ocean water surface. We adapted for most types of wave shape anatomies in shallow waters, nearshore, and onshore of the coastal zone. We used a wavelet analysis filter to detect the water wave surface. Then, through the Fourier Transformation Approach, we estimated the parameters of wave height, wavelength, and wave orientation. The comparison between the LiDAR measure estimation technique and available buoy data was then presented. We quantified the performance of the algorithm by measuring the precision and recall for the waves identification without evaluating the degree of over-segmentation. The proposed method achieves 87% accuracy of wave identification in the shallow water of coastal zones.

A Shipborne Photon-Counting Lidar for Depth-Resolved Ocean Observation

“…The instrument transient response has been reported in various oceanic lidar systems [14,15]. For example, two small secondary pulses several tens of nanoseconds after the transmit pulse of its laser have been reported for the ATLAS signal.…”

“…By emitting laser pulses, oceanic lidar measures the backscattered signals from the water surface, seawater, and sea bottom to realize depth-resolved observation [1,2]. It has become an effective tool in many fields, such as underwater target detection and identification [3][4][5], shallow water mapping [6][7][8][9][10], laser-induced fluorescence [11,12], and surface roughness measurements [13,14]. In the field of ocean ecology research, oceanic lidar has also been demonstrated to have the ability to distinguish plankton content at different depths [15,16].…”

Multiwavelength LED lidar for near-ground aerosol distribution measurement

“…Laser diode and diode-pumped solid-state laser technology as a lidar transmitter have evolved, making the lidar system more compact. This miniaturization of the lidar system is suitable for portable measurements such as the flux of aerosols and dust in urban areas or the motion of sea waves 5,6 . However, the analysis of aerosol properties from longterm, continuous datasets using lidar has been limited or requires maintenance.…”