![]() The captured images were orthorectified by geometric information surveyed by TLS, and then an image processing was performed for crack characterization. developed an automatic method based on image processing and laser scanning in assessing cracks in bridges. presented a detection technique that can simultaneously localize and quantify spalling defects on concrete surfaces using TLS. proposed a crack detection method based on a second derivative image processing of thermal images from laser heated spots, comparing with the dye penetrant inspection. configured the fundamental mathematics to determine the detectable minimum crack width with a terrestrial laser scanner in unit-based masonry by a parametric study using orthogonal offset, interval scan angle, crack orientation, and crack depth. Giri and Kharkovsky proved that a laser displacement sensor can measure a cracks’ width up to 0.7 mm on a concrete specimen. showed the feasibility of TLS by presenting that the measurable width, depth, and orientation of cracks according to the sampling interval of the laser scanner, and the range of the laser beam. ![]() The scanned data was compressed up to 50% of the original scanned data, while showing good performance in detecting cracks with various shapes.įor the detection of damages such as crack, spalling, and abrasion, Anil et al. The proposed technique was validated on a spillway wall of a concrete dam structure in South Korea. The crack detection procedure involved the following main steps: (1) classification of an image into three categories (i.e., background, structural joints and sediments, and surface) using K-means clustering according to color similarity, (2) deletion of non-crack parts on the surface using improved subtraction combined with median filtering and K-means clustering results, (3) detection of major crack objects on the surface based on Otsu’s binarization method, and (4) highlighting crack objects by morphological operations. The compressed data was then used to detect cracks on the surface using a combination of image processing algorithms. ![]() The point cloud data obtained by TLS was converted into voxel data, and further converted into an octree data structure, which significantly reduced the data size but minimized the loss of resolution to detect cracks on the surface. ![]() To efficiently utilize TLS for the surface condition assessment of large structures, a process was constructed to compress the original scanned data based on the octree structure. In this study, an effective image processing technique is proposed for crack detection on images extracted from the octree structure of TLS data. Terrestrial laser scanning (TLS) provides a rapid remote sensing technique to model 3D objects but can also be used to assess the surface condition of structures. ![]()
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