Low-cost Terrestrial Laser Scanners for Permanent Monitoring of Beach-Dune Systems

Abstract. Permanent laser scanning (PLS) is an effective tool for near-continuous monitoring of topographical changes in beach-dune systems. While PLS systems were traditionally costly, the emergence of affordable LiDAR sensors enables larger-scale setups with multiple scanners or sites. However, the different characteristics compared to high-end devices, create challenges for one-on-one replacement. To assess how low-cost sensors can replace high-end sensors, we compare the performance of a setup with several low-cost Livox AVIA sensors to a single high-end RIEGL VZ-2000i sensor in its ability to capture an embryonic dune field with large variation in topography. This is evaluated using HELIOS++ virtual laser scanning (VLS). To also assess the representativeness of the simulations, we further compare the VLS to real-world measurements with the Livox AVIA. Based on a VLS setup with six AVIAs mounted on tripods at 2 m above ground, a coverage of 52% can be obtained, which is similar to the coverage of a single RIEGL VZ-2000i on a tower 8 m high. The real-world experiments confirm the VLS results with a slightly lower point cloud coverage of 42%. Furthermore, the effective range of the Livox AVIA in a beach-dune system lies around 100-150 m. At larger ranges, only pulses at high incidence angles (angle between surface and incoming beam, >20^o) are registered at the scanner. The variations in coverage between the VLS and real-world scans highlight the need for careful consideration of the occlusion potential of different representations of the topography, beam divergence shapes, and the moisture conditions.