{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,13]],"date-time":"2026-03-13T11:34:00Z","timestamp":1773401640718,"version":"3.50.1"},"reference-count":31,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2021,2,15]],"date-time":"2021-02-15T00:00:00Z","timestamp":1613347200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Surface flatness is an important indicator for the quality assessment of concrete surfaces during and after slab construction in the construction industry. Thanks to its speed and accuracy, terrestrial laser scanning (TLS) has been popularly used for surface flatness inspection of concrete slabs. However, the current TLS based approach for surface flatness inspection has two primary limitations associated with scan range and occluded area. First, the areas far away from the TLS normally suffer from inaccurate measurement caused by low scan density and high incident angle of laser beams. Second, physical barriers such as interior walls cause occluded areas where the TLS is not able to scan for surface flatness inspection. To address these limitations, this study presents a new method that employs flat mirrors to increase the measurement range with acceptable measurement accuracy and make possible the scanning of occluded areas even when the TLS is out of sight. To validate the proposed method, experiments on two laboratory-scale specimens are conducted, and the results show that the proposed approach can enlarge the scan range from 5 m to 10 m. In addition, the proposed method is able to address the occlusion problem of the previous methods by changing the laser beam direction. Based on these results, it is expected that the proposed technique has the potential for accurate and efficient surface flatness inspection in the construction industry.<\/jats:p>","DOI":"10.3390\/rs13040714","type":"journal-article","created":{"date-parts":[[2021,2,15]],"date-time":"2021-02-15T22:58:01Z","timestamp":1613429881000},"page":"714","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":21,"title":["Laser Scanning Based Surface Flatness Measurement Using Flat Mirrors for Enhancing Scan Coverage Range"],"prefix":"10.3390","volume":"13","author":[{"given":"Fangxin","family":"Li","sequence":"first","affiliation":[{"name":"Department of Building and Real Estate, Hong Kong Polytechnic University, Kowloon, Hong Kong 999077, China"}]},{"given":"Heng","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Building and Real Estate, Hong Kong Polytechnic University, Kowloon, Hong Kong 999077, China"}]},{"given":"Min-Koo","family":"Kim","sequence":"additional","affiliation":[{"name":"Department of Architectural Engineering, Chungbuk National University, Cheongju 28644, Korea"}]},{"given":"King-Chi","family":"Lo","sequence":"additional","affiliation":[{"name":"Department of Building and Real Estate, Hong Kong Polytechnic University, Kowloon, Hong Kong 999077, China"}]}],"member":"1968","published-online":{"date-parts":[[2021,2,15]]},"reference":[{"key":"ref_1","unstructured":"British Standards Institution (BSI) (2009). 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