3D observation of water surface in the nearshore using stereo camera

Abstract

Understanding of coastal morphology in the nearshore is challenging due to complicated interactions between bottom bathymetry and hydrodynamics, which are induced by wave breaking and turbulent flows. Remote sensing methods have been developed to increase coverage of coastal observations, providing spatially and temporally high-resolution measurements of ocean surfaces. As for one of them, a stereo imaging system can be used to re-construct water surfaces in 3-D from a stereo image set obtained by the synchronized two cameras of it. In this study, laboratory experiments were conducted in a two-dimensional wave flume (100 m long, 2 m wide and 3 m deep) at Chonnam National University, Korea, in order to consider morphological beach processes caused by storms. Herein, a stereo imaging system (called WASS) was installed on the top to measure both beach face and water surface in 3-D continuously changing in time over the swash and surf zones. Wave heights and periods over the cross-shore transect in the surf zone were extracted from the measurements of 3-D water surfaces in time. The extracted wave results were well compared with the in-situ sensor data. Spatial wave run-ups could be also derived from the 3-D water surface measurements. The spatial and temporal hydrodynamic results obtained by the stereo image system were used to comprehensively describe morphological changes of the beach and be inputs to numerical simulations.