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Estimation of the residual bearing capacity of corrosion damaged bridge beams using 3D scanning and finite element analysis
Published in Hiroshi Yokota, Dan M. Frangopol, Bridge Maintenance, Safety, Management, Life-Cycle Sustainability and Innovations, 2021
High-resolution 3D scanning combined with finite element analysis (FEA) provides a robust method for enhancing the accuracy of residual capacity estimations of corrosion damaged beams. 3D scanning improves the precision of the underlying measurements while FEA allows for the full profile of the corrosion to be considered in the analysis. Structured-light 3D scanning technology enables sub-millimeter point accuracy (Artec3D 2017). The principle of structured-light imaging is to extract the 3D surface of an object based on information collected from the deformation of a projected structured-light pattern (Motley). The scanner projects a series of reference patterns onto an object, collects the distorted pattern with cameras, and uses triangulation to calculate the surface geometry (Motley). In addition to collecting geometric information, structured-light scanning can capture the color and texture of an object that may support qualitative assessment and documentation efforts.
Assembly and Welding Processes and Their Monitoring and Control
Published in Osita D. I. Nwokah, Yildirim Hurmuzlu, The Mechanical Systems Design Handbook, 2017
S. Jack Hu, Elijah Kannatey-Asibu
In the case of welding, for example, the sensed objects include the joint to be welded, weld pool, under bead, and bead surface. Some of the problems associated with optical sensing include the extreme brightness of the plasma plume compared to that of the molten pool (high contrast), and dependence of the intensity on processing conditions. Spatter, fumes, and flux also may obscure the object to some extent. As a result of these problems, separate illumination is often used to counteract the effect of plasma plume illumination, maintain a stable intensity that is appropriate for the sensor, enhance contrast, and provide a brightness level that is suitable for the sensor. This increases the system resolution. The separate illumination may be in the form of either structured light or general illumination, i.e., nonstructured light. A structured light is a pattern of lines or a grid of light projected onto the object to help provide information on the three-dimensional shape of the object based on the apparent distortion of the pattern.
Glossary of Computer Vision Terms
Published in Edward R. Dougherty, Digital Image Processing Methods, 2020
Robert M. Haralick, Linda G. Shapiro
Structured light refers to a technique of projecting a carefully designed light pattern on a scene and viewing the scene from a different direction. Usually the pattern consists of successive planes of light at different positions and orientations. Those pixels which image a surface patch which is lit by a known light pattern have sufficient information to determine the 3D coordinates of the surface patch since the light pattern is designed so that the line of sight passing through the pixel and the lens will intersect the known light pattern in a unique point. For stereo matching purposes, the structured light pattern may be “unstructured” in the sense of being a texture pattern or consisting of random stipples.
Regularising disparity estimation via multi task learning with structured light reconstruction
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2023
Alistair Weld, Joao Cartucho, Chi Xu, Joseph Davids, Stamatia Giannarou
Structured light is currently the most dense and accurate approach for creating ground truth information for depth datasets. Example datasets that were created using structured light include NYU (Silberman and Fergus 2011), Middlebury Stereo (Scharstein and Szeliski 2003; Scharstein et al. 2014) and SCARED. Structured light is the projection of patterns into a scene, which when captured by an imaging camera, allows for depth recovery through analysis of the pattern distortions (Salvi et al. 2004). Commonly, these pattern projection images are used exclusively for ground truth depth generation. Once depth has been captured, the pattern projection images are discarded afterwards. However, error will occur in the conversion process due to difficulties relating to the environment, surface properties and the hardware (Gupta et al. 2011; Jensen et al. 2017; Rachakonda et al. 2019). Primarily, errors will occur at the pixel classification stage which for example can be caused by reflections or hardware malfunction. This means that the information within the structured light images and the generated depth maps are not the same.
Defect inspection system of nuclear fuel pellet end faces based on machine vision
Published in Journal of Nuclear Science and Technology, 2020
Bin Zhang, Mengmeng Liu, Yongzhi Tian, Ge Wu, Xiaohui Yang, Songyang Shi, Jianning Li
In the laboratory, the fuel pellet imitation is used for image acquisition and image algorithm verification. Imitation is consistent with the real fuel pellet in physical properties such as appearance and size. The structure of the end-face image acquisition system is shown in Figure 2. Image acquisition adopts acA1600-20gm German Basler face array camera and the Lighting adopts left-right bilateral ultra-fine grating structure light. Structured light is the process of projecting a known pattern (often grids or horizontal bars) on to a scene. A sample about structured light projector is shown in Figure 3. In the paper, the structured light projection device of grating type is adopted to generate the ultra-fine paralleled beam with the line thickness being 50 µm and the line gap being 200 µm. When being projected to the surface of the detected objects, the structured light of grating type will generate distortion change in accordance with the change of end-face shape. So, illumination of structured light can be used to reflect the morphological characteristics of the object surface. The lens uses high resolution and low distortion telecentric lens. The acquisition system is suitable for automatic defect measurement of tiny nuclear fuel pellet in this paper.
Digital healthcare technologies: Modern tools to transform prosthetic care
Published in Expert Review of Medical Devices, 2021
Isaac A Cabrera, Trinity C. Pike, Joanna M. McKittrick, Marc A. Meyers, Ramesh R. Rao, Albert Y. Lin
Structured light scanning is a noninvasive, fast, and accurate method for acquiring 3D models. Easily operated using a handheld scanner, the procedure begins when a projector casts light patterns (also known as fringe patterns) onto the surface of interest. A camera array records the distorted light pattern, then the 3D geometry is determined by calculating the differences between points in the captured images (through pattern fringe triangulation) [26,29]. The image of the surface is collected without the pattern to gather textural information. Finally, the geometric and textural data are combined to form a 3D model of the residual limb.