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A Cost‐Effective Laser Scanning Method for Mapping Stream Channel Geometry and Roughness
Author(s) -
Lam Norris,
Nathanson Marcus,
Lundgren Niclas,
Rehnström Robin,
Lyon Steve W.
Publication year - 2015
Publication title -
jawra journal of the american water resources association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.957
H-Index - 105
eISSN - 1752-1688
pISSN - 1093-474X
DOI - 10.1111/1752-1688.12299
Subject(s) - point cloud , channel (broadcasting) , laser scanning , surface finish , laser , surface roughness , scale (ratio) , lidar , geometry , optics , remote sensing , computer science , materials science , geology , mathematics , engineering , physics , mechanical engineering , computer vision , telecommunications , quantum mechanics , composite material
This brief pilot study implements a camera‐based laser scanning system that potentially offers a viable, cost‐effective alternative to traditional terrestrial laser scanning ( TLS ) and Li DAR equipment. We adapted a low‐cost laser ranging system ( SICK LSM 111) to acquire area scans of the channel and bed for a temporarily diverted stream. The 5 m × 2 m study area was scanned at a 4 mm point spacing which resulted in a point cloud density of 5,600 points/m 2 . A local maxima search algorithm was applied to the point cloud and a grain size distribution of the stream bed was extracted. The 84th and 90th percentiles of this distribution, which are commonly used to characterize channel roughness, were 90 mm and 109 mm, respectively. Our example shows the system can resolve both large‐scale geometry (e.g., bed slope and channel width) and small‐scale roughness elements (e.g., grain sizes between about 30 and 255 mm) in an exposed stream channel thereby providing a resolution adequate for the estimation of ecohydraulic roughness parameters such as Manning's n . While more work is necessary to refine our specific field‐deployable system's design, these initial results are promising in particular for those working on a limited or fixed budget. This opens up a realm of laser scanning applications and monitoring strategies for water resources that may not have been possible previously due to cost limitations associated with traditional TLS systems.