Impact of High-Resolution Topographic Mapping on Beach Morphological Analyses Based on Terrestrial LiDAR and Object-Oriented Beach Evolution

Abstract

This research applied terrestrial LiDAR for laboratory beach evolution experiments to quantify the impact of resolution on topographic mapping and change analyses. The multi-site registration and multi-temporal scanning processes produced high accuracy (−0.002 ± 0.003 m) topographic models in a wave tank environment. Morphological analyses based on surface change and profiles showed that models of all resolutions were capable of capturing major sediment changes in relatively smooth areas. However, higher resolution models were necessary in areas with rough surfaces and sudden elevation changes, while coarser resolution models smoothed the roughness and underestimated feature height (e.g., peaks and troughs). Decreasing resolutions from 1 to 10 cm resulted in a 2% underestimation of erosional volumes with a linear regression of y = −0.0964x + 0.4185 (R 2 = 0.9651) and 3.5% overestimation of depositional volumes with a linear regression of y = 0.0664x + 0.3308 (R 2 = 0.3645). However, its impact on erosion and deposition volume assessment based on object-oriented beach evolution analysis is less significant, except when fragment objects dominate the sediment changes. For Coastal Morphology Analyst (CMA), the impact of resolution is more observable through 2D object mapping in terms of object size, number, and spatial distribution. Finally, wave modeling experiments proved that resolutions caused significant changes on the behavior of the maximum wave height, the shape of the wave fronts and magnitudes of the currents.

Micro-Topography Mapping through Terrestrial LiDAR in Densely Vegetated Coastal Environments

“…Through tracking the time where a pulse occurred in a laser beam, as trigged by an object, LiDAR technology can measure the location of the object and, hence, produces dense point clouds with X, Y, and Z coordinates for objects on or above the ground surface. The derived raw LiDAR point clouds from the multi-site scanning of typical coastal landscapes are a mixture of measurements from the ground, marshes, birds and boats, and from artificial facilities such as floating buoys and buildings, as well as other harbor infrastructure [19,26,38]. To generate DEM from these dense point surveys, points reflected from the ground surface need to be filtered first and then interpolated into 3-D terrain models of the terrain [39].…”

“…Among the new remote sensing technologies, terrestrial LiDAR has demonstrated significant advantages for quick and accurate 3D topographical mapping [26], and started to fill the gap between satellite-based remotely sensed mapping and tedious point-based field surveys. Terrestrial LiDAR, also called terrestrial laser scanning, is a portable surveying system mounted on a tripod that can rotate 360 degrees to acquire virtual realitylike color-coded dense point clouds of the surrounding environment.…”

Citizen science for monitoring seasonal-scale beach erosion and behaviour with aerial drones

“…Nowadays, beach topographic data is obtainable using a variety of ground-based (graded rods 16 , surveyor-grade global positioning systems or total stations 17 , terrestrial LiDAR 18 ) or aerial-based (airborne LiDAR 19 , traditional photogrammetry 20 , 21 , unmanned aerial vehicles 22 , 23 ) approaches. While ground-based surveying methods are labour intensive and of limited spatial coverage, airborne LiDAR or traditional photogrammetric approaches are cost-prohibitive for monitoring purposes, especially in developing countries.…”

Photogrammetric UAV Mapping of Terrain under Dense Coastal Vegetation: An Object-Oriented Classification Ensemble Algorithm for Classification and Terrain Correction

“…Discrepancies among the data or seasonal and annual landscape changes can introduce significant errors in the ever-changing coastal environments affected by hydrodynamics, hazards, and human activities. Furthermore, LiDAR boasts the best for high-resolution terrain mapping [18,19] among current mapping technologies, but the equipment is costly. Frequent deployment of airborne LiDAR for surveys is cost prohibitive, urging for affordable method for rapid and accurate measurements without relying on out-of-dated historical data [2,3].…”