Modelling of Submerged Targets Affected by Refraction Using Green-Wavelength Leica C10 Scanstation

Abstract

This paper presents an extensive approach into the capability of terrestrial laser scanning (TLS) operating at the 532 nm green wavelength for modelling submerged targets under varying water depths with the effects of refraction acting upon the targets. In this research, a Leica 0 C10 TLS was deployed to scan a controlled rectangular pool containing a submerged cuboid target and check markers positioned equally at depths ranging from 0 to 15 cm incrementally. The Point cloud data were processed using Leica Cyclone Register and 3DSurvey software, while a MATLAB-based algorithm to solve the refraction correction based on Snell’s law was applied. Results demonstrated accountable horizontal and vertical displacements of submerged markers, which are consistent with theoretical refraction effects, averaging 2cm and 2mm for the horizontal and vertical displacement, respectively, with the presence of water depth at 3cm assessed by visual evaluation of the markers. The post-processing correction using MATLAB significantly improved the alignment precision and allowed 3D mesh models to approximate the true target dimensions more accurately, presenting the mean error vectors of 1.36m for 0, 0.34m for 0, and 0.41m for 0. This paper highlights the potential of 532 nm TLS for shallow-water 3D modelling applications and the significance of refraction correction.