Evaluation of a LIDAR Land-Based Mobile Mapping System for Monitoring Sandy Coasts

Abstract

Abstract:The Dutch coast is characterized by sandy beaches flanked by dunes. Understanding the morphology of the coast is essential for defense against flooding of the hinterland. Because most dramatic changes of the beach and the first dune row happen during storms, it is important to assess the state of the coast immediately after a storm. This is expensive and difficult to organize with Airborne Laser Scanning (ALS). Therefore, the performance of a Land-based Mobile Mapping System (LMMS) in mapping a stretch of sandy Dutch coast of 6 km near the municipality of Egmond is evaluated in this research. A test data set was obtained by provider Geomaat using the StreetMapper LMMS system. Both the relative quality of laser point heights and of a derived Digital Terrain model (DTM) are assessed. First, the height precision of laser points is assessed a priori by random error propagation, and a posteriori by calculating the height differences between close-by points. In the a priori case, the result is a theoretical laser point precision of around 5 cm. In the a posteriori approach it is shown that on a flat beach a relative precision of 3 mm is achieved, and that almost no internal biases exist. In the second analysis, a DTM with a grid size of 1 m is obtained using moving least squares. Each grid point height includes a quality description, which incorporates both measurement precision and terrain roughness. Although some problems remain with the scanning height of 2 m, which causes shadow-effect behind low dunes, it is concluded that a laser LMMS enables the acquisition of a high quality DTM product, which is available within two days.

Monitoring Capabilities of a Mobile Mapping System Based on Navigation Qualities

“…Compared to airborne applications, MLS is able to capture more details of the environment as it is much closer to the targets, hence often used in mobile mapping applications to build 3D models (Kaartinen et al, 2012). Recent improvements in both navigation system accuracy and laser scanner performance allows the applications of MLS based monitoring and surveying, which has a higher demand for accuracy and detail (Vu et al, 2004, Bitenc et al, 2011, González-Jorge et al, 2012. * Corresponding author Road and railway surveying applications have grown towards using MLS rather than traditional surveying methods as MLS can reduce safety risks by taking surveyors off the road while also generating 3D road models efficiently.…”

A Wireless Sensor Network Framework for Real-Time Monitoring of Height and Volume Variations on Sandy Beaches and Dunes

“…Therefore, the comparison between the topographic configuration before and after storms would provide the basis for volume shift calculations. The same end results can be obtained with remote sensing technologies, such as LiDAR [35,36] and satellite imagery [37,38]. As for sediment tracing, these techniques do not provide sensible information about sand movement during the periods when it should occur the most: the high-energy events.…”

Rigorous Point-to-Plane Registration of Terrestrial Laser Scans

“…increases with the cosine of the incidence angle, such that (Bitenc et al, 2010). The signal-to-noise (SNR) ratio of a laser return deteriorates with the cosine of the incidence angle, and the square of the range (Soudarissanane et al, 2011), which increases the uncertainty of the range.…”