Articles de revues sur le sujet « Triangulation-based laser scanning »
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IBARAKI, Soichi, Yoshitomo KITAGAWA, Yoshihiro KIMURA et Shizuo NISHIKAWA. « 0203 Reduction of Measurement Error Induced by Laser Speckles in Scanning Operations using a Triangulation-based Laser displacement Sensor ». Proceedings of International Conference on Leading Edge Manufacturing in 21st century : LEM21 2015.8 (2015) : _0203–1_—_0203–4_. http://dx.doi.org/10.1299/jsmelem.2015.8._0203-1_.
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Tu, Dawei, Pan Jin et Xu Zhang. « Geometrical Model of Laser Triangulation System Based on Synchronized Scanners ». Mathematical Problems in Engineering 2019 (25 mars 2019) : 1–10. http://dx.doi.org/10.1155/2019/3503192.
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In traditional synchronized scanning system, the trajectory of the 3D scanning point is modeled as a circle when the thickness of rotated mirror is assumed to be zero. In this paper, a novel method to model the geometric measurement of synchronized scanning triangulation in the unfolded light path is proposed. Unlike most existing recent works, the 3D coordinate of the target is reasoned from the geometrical model, which includes all 14 system parameters. Further, the performance of the system precision can be analyzed and the importance of the thickness of rotated mirror is confirmed. In the experiment, a synchronized scanning system is developed. The experimental result demonstrates that the value of measurement uncertainty at a distance of 0.5m is 0.75mm and at a distance of 5m is 6.68mm. The standard deviations from the measurement point to the fitting plane at a distance of 0.5 m and 5 m are 1.10 mm and 19.73 mm, respectively.
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Comsa, Andrei, Inocentiu Maniu et Erwin Christian Lovasz. « Triangulation 3D Scanning Method in Biomedical Reconstruction ». Solid State Phenomena 166-167 (septembre 2010) : 145–48. http://dx.doi.org/10.4028/www.scientific.net/ssp.166-167.145.
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In this paper is presented the 3D acquisition and reconstruction process of complex geometry objects: two types of hip and cervical-cephalic prosthesis. The reconstruction process is based on triangulation single camera solution method with a 3D optical non-contact scanner which uses an emitted laser beam to sweep the object surfaces.
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Panov, Kirill, et Anatoly Borodin. « System of technical vision based on active laser triangulation method ». MATEC Web of Conferences 239 (2018) : 01003. http://dx.doi.org/10.1051/matecconf/201823901003.
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The number of failures, the percentage of faulty electric locomotives, and the number of unplanned repairs remain high at the enterprises for repair of traction rolling stock of the network of the main-line Russian railways. It was found that the main reasons for this situation are the unsatisfactory quality of current repairs and maintenance, the insufficient level of mechanization and automation of labor-intensive repair processes. The paper considers an existing positive example of the use of robotic equipment in assembly production for the repair of traction rolling stock. The analysis and classification of sensor control devices for industrial robots is performed. A method for controlling the driving devices of the repair equipment is proposed by obtaining a spatial-geometric image of the object’s surface before the beginning of technological processing by the method of active laser triangulation scanning. The principle of the action of three-dimensional scanning is described; a number of equipment with its technical characteristics and software used during the research in the laboratory of the university is listed. The result of the experiment of the proposed method on the model of the truck frame of the electric locomotive is presented. The metrological characteristics of the measurement results are calculated, allowing comparing and assessing the accuracy of the model obtained and the mock-up of the rolling stock truck. Based on the results of these calculations, it can be said with certainty that all errors and deviations of the results from true values lie within the limits of the norm and this technology can be used to design a vision system for robotic equipment.
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Li, Xiao Qin, Zhi Xiong Lu, Lan Ying Zhao, Zheng Hao Li, Bing Guo et Xue Feng Bai. « The Measurement of Three-Dimensional Road Roughness Based on Laser Triangulation ». Advanced Materials Research 346 (septembre 2011) : 812–16. http://dx.doi.org/10.4028/www.scientific.net/amr.346.812.
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This article did some non-contact measurement by laser triangulation principle on the A level hard road roughness, based on CCD imaging principle,used scanning galvanometer, which improved the measurement speed and surface measurement range, , drew the three-dimensional surface roughness profile curve by interpolation and fitting,It was in accordance with the standard range of A-road height spectrum. This measurement method have important guiding significance on the hard road roughness measurement and practice of the design of the relatively flat three-dimensional contours.
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Liu, Qi Fang. « Measuring Coaxiality with Optoelectronic and Non-Contact Based on Helical Scanning ». Advanced Materials Research 588-589 (novembre 2012) : 1002–5. http://dx.doi.org/10.4028/www.scientific.net/amr.588-589.1002.
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In view of the characteristic of the inefficiency on measuring coaxiality manually in industry, we put forward to studying on a laser triangulation san method[1] for measuring distance to measure coaxiality. It takes relative motion between the measurement thing and displacement laser sensor to implement helical scan motion and gain the data of spiral scanning projection based on step servo system by gyration and the axial feed. This method can improve manufacture efficiency and achieve the demand of online automatic testing. Finally, the way of implementation of this system would be discussed in this paper, meanwhile, it would provide simulation results of the method and actually feasibility analysis .
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van der Lucht, J., M. Bleier, F. Leutert, K. Schilling et A. Nüchter. « STRUCTURED-LIGHT BASED 3D LASER SCANNING OF SEMI-SUBMERGED STRUCTURES ». ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences IV-2 (28 mai 2018) : 287–94. http://dx.doi.org/10.5194/isprs-annals-iv-2-287-2018.
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In this work we look at 3D acquisition of semi-submerged structures with a triangulation based underwater laser scanning system. The motivation is that we want to simultaneously capture data above and below water to create a consistent model without any gaps. The employed structured light scanner consist of a machine vision camera and a green line laser. In order to reconstruct precise surface models of the object it is necessary to model and correct for the refraction of the laser line and camera rays at the water-air boundary. We derive a geometric model for the refraction at the air-water interface and propose a method for correcting the scans. Furthermore, we show how the water surface is directly estimated from sensor data. The approach is verified using scans captured with an industrial manipulator to achieve reproducible scanner trajectories with different incident angles. We show that the proposed method is effective for refractive correction and that it can be applied directly to the raw sensor data without requiring any external markers or targets.
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Altuntas, C. « TRIANGULATION AND TIME-OF-FLIGHT BASED 3D DIGITISATION TECHNIQUES OF CULTURAL HERITAGE STRUCTURES ». International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B2-2021 (28 juin 2021) : 825–30. http://dx.doi.org/10.5194/isprs-archives-xliii-b2-2021-825-2021.
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Abstract. This study aims to introduce triangulation and ToF measurement techniques used in three-dimensional modelling of cultural heritages. These measurement techniques are traditional photogrammetry, SfM approach, laser scanning and time-of-flight camera. The computer based approach to photogrammetric measurement that is named SfM creates dense point cloud data in a short time. It is low-cost and very easy to application. However traditional photogrammetry needs a huge effort for creating 3D wire-frame model. On the other hand active measurement techniques such as terrestrial laser scanner and time-of-flight camera have also been used in three-dimensional modelling for more than twenty years. Each one has specific accuracy and measurement effectiveness. The large or small structures have different characters, and require proper measurement configurations. In this study, after these methods are introduced, their superior and weak properties in cultural heritage modelling to make high accuracy, high density and labour and cost effective measurement.
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Huang, H., C. Hu, F. Zhang et H. Xue. « RESEARCH ON VISUALIZATION OF GROUND LASER RADAR DATA BASED ON OSG ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-3 (30 avril 2018) : 595–99. http://dx.doi.org/10.5194/isprs-archives-xlii-3-595-2018.
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Three-dimensional (3D) laser scanning is a new advanced technology integrating light, machine, electricity, and computer technologies. It can conduct 3D scanning to the whole shape and form of space objects with high precision. With this technology, you can directly collect the point cloud data of a ground object and create the structure of it for rendering. People use excellent 3D rendering engine to optimize and display the 3D model in order to meet the higher requirements of real time realism rendering and the complexity of the scene. OpenSceneGraph (OSG) is an open source 3D graphics engine. Compared with the current mainstream 3D rendering engine, OSG is practical, economical, and easy to expand. Therefore, OSG is widely used in the fields of virtual simulation, virtual reality, science and engineering visualization. In this paper, a dynamic and interactive ground LiDAR data visualization platform is constructed based on the OSG and the cross-platform C++ application development framework Qt. In view of the point cloud data of .txt format and the triangulation network data file of .obj format, the functions of 3D laser point cloud and triangulation network data display are realized. It is proved by experiments that the platform is of strong practical value as it is easy to operate and provides good interaction.
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Tu, Da Wei, Xu Zhang, Kai Fei et Xi Zhang. « Laser Stereo Vision-Based Position and Attitude Detection of Non-Cooperative Target for Space Application ». Advanced Materials Research 1039 (octobre 2014) : 242–50. http://dx.doi.org/10.4028/www.scientific.net/amr.1039.242.
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Vision measurement for non-cooperative targets in space is an essential technique in space counterwork, fragment disposal, satellite on-orbit service, spacecraft rendezvous, because the position and attitude of the target aircraft or the object should be detected first of all in the process. The 2D passive camera loses the depth information and can not measure the position and attitude of non-cooperative target. Several kinds of range imaging methods are alternatives. The traditional triangulation method can provide very high precision range measurement at close range but the nature of the triangulation geometry means that the uncertainty grows when the range increases. Laser radar (LIDAR) based on TOF (time of flight) or phase difference principle is suitable for middle and long range, but it can not fit for short range. A novel structure system is put forward, in which a so-called synchronous scanning triangulation method is adopted combining a LIDAR system. The synchronous scanning triangulation system plays a role at the range from 0.5m to 10m for object’s attitude, and the LIDAR system plays a role at the range from 10m to 200m for object’s position (direction and range).They are merged into one path, and do not influence each other because of using two different wavelengths respectively. This mechanism makes the system more compact and less weight. The system performances, such as the measurement range and precision, are analyzed according to the system parameters. The principle prototype is designed and established, and the experimental results confirm that its performance is promising and can satisfy the requirement for space application.
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GONZALEZ, Saul, et Soichi IBARAKI. « Reduction of measurement error of a Triangulation-Based Laser Displacement Sensor in a profile scanning measurement ». Proceedings of Conference of Chugoku-Shikoku Branch 2020.58 (2020) : 10b1. http://dx.doi.org/10.1299/jsmecs.2020.58.10b1.
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Mezei, Adrián, et Tibor Kovács. « Curvature Adaptive 3D Scanning Transformation Calculation ». Periodica Polytechnica Electrical Engineering and Computer Science 62, no 4 (13 juin 2018) : 107–16. http://dx.doi.org/10.3311/ppee.11540.
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Three-dimensional objects can be scanned by 3D laser scanners that use active triangulation. These scanners create three-dimensional point clouds from the scanned objects. The laser line is identified in the images, which are captured at given transformations by the camera, and the point cloud can be calculated from these. The hardest challenge is to construct these transformations so that most of the surface can be captured. The result of a scanning may have missing parts because either not the best transformations were used or because some parts of the object cannot be scanned. Based on the results of the previous scans, a better transformation plan can be created, with which the next scan can be performed. In this paper, a method is proposed for transforming a special 3D scanner into a position from where the scanned point can be seen from an ideal angle. A method is described for estimating this transformation in real-time, so these can be calculated for every point of a previous scan to set up a next improved scan.
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Giganto, Sara, Susana Martínez-Pellitero, Eduardo Cuesta, Víctor M. Meana et Joaquín Barreiro. « Analysis of Modern Optical Inspection Systems for Parts Manufactured by Selective Laser Melting ». Sensors 20, no 11 (4 juin 2020) : 3202. http://dx.doi.org/10.3390/s20113202.
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Metal additive manufacturing (AM) allows obtaining functional parts with the possibility of optimizing them topologically without affecting system performance. This is of great interest for sectors such as aerospace, automotive, and medical–surgical. However, from a metrological point of view, the high requirements applied in these sectors constitute a challenge for inspecting these types of parts. Non-contact inspection has gained great relevance due to the rapid verification of AM parts. Optical measurement systems (OMSs) are being increasingly adopted for geometric dimensioning and tolerancing (GD&T) verification within the context of Industry 4.0. In this paper, the suitability (advantages and limitations) of five different OMSs (based on laser triangulation, conoscopic holography, and structured light techniques) for GD&T verification of parts manufactured by selective laser melting (SLM) is analyzed. For this purpose, a specific testing part was designed and SLM-manufactured in 17-4PH stainless steel. Once the part was measured by contact (obtaining the reference GD&T values), it was optically measured. The scanning results allow comparing the OMSs in terms of their inspection speed as well as dimensional and geometrical accuracy. As a result, two portable systems (handheld laser triangulation and structured blue-light scanners) were identified as the most accurate optical techniques for scanning SLM parts.
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Ilarionov, Raycho, et Krasimir Krastev. « А System for Input of 3D Objects into Computing Environment ». Environment. Technology. Resources. Proceedings of the International Scientific and Practical Conference 2 (8 août 2015) : 17. http://dx.doi.org/10.17770/etr2013vol2.849.
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This paper proposes an approach for design and implementation of automated 3D scanner used for input of mechanical 3D objects into computing environment. The presented model of 3D scanner is based on kinematic diagram of positioning system with 5 degree of freedom – 3 linear and 2 rotational, each driven by servo motors. For distance measuring is used laser scanning head with rotational triangulation. The paper describes also algorithms for functional control of the scanning process, obtaining of point cloud, object reconstruction and export to standard CAD format. Keywords
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Hošek, Jan, et Petr Linduška. « Simple Modification of a Commercial Laser Triangulation Sensor for Distance Measurement of Slot and Bore Side Surfaces ». Sensors 21, no 20 (18 octobre 2021) : 6911. http://dx.doi.org/10.3390/s21206911.
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The aim of the research is to analyze the possibility of the development and realization of a common laser triangulation sensor arrangement-based probe for the measurement of slots and bore sides with the help of a mirror attachment. The analysis shows the feasibility and limits of the solution with respect to the maximum measurement depth and surface distance measurement working range. We propose two possible solutions: one for maximizing the ratio of the measurement depth to the measured bore size and the second for maximizing the total depth, intended for the measurement of slots and large bore sizes. We analyzed measurement error sources. We found that the errors related to the reflection mirror misalignment can be fully compensated. We proved the validity of the proposed solution with the realization of a commercial laser triangulation sensor-based probe and demonstrated a slot side and a bore side surface distance scanning measurement. The probe working range was assessed with regard to the obscuration effect of optical beams.
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Wei, Zheng, Yinze Wang, Wenlin Weng, Zhen Zhou et Zhenguo Li. « Research on Tunnel Construction Monitoring Method Based on 3D Laser Scanning Technology ». Symmetry 14, no 10 (3 octobre 2022) : 2065. http://dx.doi.org/10.3390/sym14102065.
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A tunnel is a symmetric structure working under uncertain load. In the traditional method of monitoring and measurement of tunnel deformation, only a small number of symmetric measuring point displacements are engaged to represent the overall deformation of the tunnel, and it is difficult to fully reflect the displacement changes of the tunnel during the construction process. In this paper, a deformation monitoring method is proposed for the tunnel construction process based on 3D laser scanning technology. Initially, 3D laser scanning was used to obtain scattered clouds of irregular structures considering the New Austrian Tunneling Method (NATM). Afterward, the modified B-spline interpolation and greedy triangulation were used to fit the surfaces. Moreover, the normal vector matrix was innovatively applied to express the deformation of the tunnel fitting surface, which solved the problem of scattered point clouds in 3D laser scanning. A normal vector was obtained by the intersection of the normal of one fitted surface with the other. Subsequently, the maximum entropy method was introduced to form the probability density function of the normal vector, and the 1% and 5% probability eigenvalues were used to analyze the overall deformation trend of the tunnel. Finally, the eigenvalue of 5% probability, which was less affected by construction uncertainties, was selected for analysis. This way, the analysis and prediction method for overall tunnel deformation was established.
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Bolotov, M. A., V. А. Pechenin, N. V. Ruzanov et E. J. Kolchina. « Surface recognition of machine parts based on the results of optical scanning ». Information Technology and Nanotechnology, no 2391 (2019) : 342–49. http://dx.doi.org/10.18287/1613-0073-2019-2391-342-349.
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To predict the quality parameters of products (in particular, the assembly parameters) mathematical models were implemented in the form of computer models. To ensure the adequacy of calculations, it is necessary to have information about the actual geometry of the parts, which can be obtained using noncontact measurements of parts of the assembly. As a result of measuring parts and components using optical or laser scanner, a large dimension array of measured points is formed. After standard processing (e.g. noise removal, combining the scans, smoothing, creating triangulation mesh), the recognition of individual surfaces of parts becomes necessary. This paper presents a neural network model that allows the recognition of elements based on an array of measured points obtained by scanning.
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Altantsetseg, Enkhbayar, Yuta Muraki, Fumito Chiba et Kouichi Konno. « 3D Surface Reconstruction of Stone Tools by Using Four-Directional Measurement Machine ». International Journal of Virtual Reality 10, no 1 (1 janvier 2011) : 37–43. http://dx.doi.org/10.20870/ijvr.2011.10.1.2800.
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In this paper, we present a whole procedure for constructing 3D models of stone tools including scanning, data acquisition and surface reconstruction with hole-filling. The process of scanning hundreds or thousands of small objects is time consuming. Our original 3D laser scanner optimizes the scanning process and reduces time significantly by four directional scanning of many small objects simultaneously. To reconstruct surface of stone tools, the scanned point clouds are processed with a new triangulation method that preserves the properties of sharp edges. Our approach is based on a projection based method in which points are distinguished into neighboring layers with a point cloud slicing method to be individually reconstructed. In addition, we introduce a simple hole-filling algorithm for mesh completion of models. The main advantages of our approach are speed and efficiency for reconstruction of many small objects.
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Mayer, J. R. « Polarization optics design for a laser tracking triangulation instrument based on dual-axis scanning and a retroreflective target ». Optical Engineering 32, no 12 (1993) : 3316. http://dx.doi.org/10.1117/12.151296.
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Shiou, Fang Jung, et Y. W. Deng. « Simultaneous Flatness and Surface Roughness Measurement of a Plastic Sheet Using a Fan-Shaped Laser Beam Scanning System ». Key Engineering Materials 381-382 (juin 2008) : 233–36. http://dx.doi.org/10.4028/www.scientific.net/kem.381-382.233.
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A fan-shaped laser beam scanning measuring system based on the triangulation principle, was newly developed in this study to measure simultaneously the flatness and the surface roughness of a surface plate with good reflectivity after a suitable calibration. The developed system mainly consists of a micro-focus fan-shaped line laser, an image processing system, a PC-based 3-axis machine, and a PC. The height value of the object can be calculated, based on the offset between the position projected onto the object and the position projected onto the platform, after carrying out the height calibration with gauge blocks. According to the scattering theorem, a correlation between the surface roughness of the test object measured with a precision stylus instrument and the average fringe width projected onto the test object surface, has been constructed.
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Lindner, Lars, Oleg Sergiyenko, Julio C. Rodríguez-Quiñonez, Moises Rivas-Lopez, Daniel Hernandez-Balbuena, Wendy Flores-Fuentes, Fabian Natanael Murrieta-Rico et Vera Tyrsa. « Mobile robot vision system using continuous laser scanning for industrial application ». Industrial Robot : An International Journal 43, no 4 (20 juin 2016) : 360–69. http://dx.doi.org/10.1108/ir-01-2016-0048.
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Purpose The purpose of this paper is the presentation and research of a novel robot vision system, which uses laser dynamic triangulation, to determine three-dimensional (3D) coordinates of an observed object. The previously used physical operation principle of discontinuous scanning method is substituted by continuous method. Thereby applications become possible that were previously limited by this discretization. Design/methodology/approach The previously used prototype No. 2, which uses stepping motors to realize a discontinuous laser scan, was substituted by the new developed prototype No. 3, which contains servomotors, to achieve a continuous laser scan. The new prototype possesses only half the width and turns out to be significantly smaller and therefore lighter than the old one. Furthermore, no transmissions are used, which reduce the systematic error of laser positioning and increase the system reliability. Findings By using a continuous laser scan method instead of discontinuous laser scan method, dead zones in the laser scanner field can be eliminated. Thereby, also by changing the physical operation principle, the implementation of applications is allowed, which previously was limited by the fixed step size or by the object distance under observation. By using servomotors instead of stepping motors, also a significant reduced positioning time can be accomplished maintaining the relative positioning error less than 1 per cent. Originality/value The originality is based on the substitution of the physical operation principle of discontinuous by continuous laser scan. The previously used stepping motors discretized the laser scanner field and thereby produced dead zones, where 3D coordinates cannot be detected. These stepping motors were substituted by servomotors to revoke these disadvantages and provide a continuous laser scan, where dead zones in the field of view get eliminated and the step response of the laser scanner accelerated.
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Xu, Jingzhong, Jie Shan et Ge Wang. « Hierarchical Modeling of Street Trees Using Mobile Laser Scanning ». Remote Sensing 12, no 14 (19 juillet 2020) : 2321. http://dx.doi.org/10.3390/rs12142321.
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This paper proposes a novel method to reconstruct hierarchical 3D tree models from Mobile Laser Scanning (MLS) point clouds. Starting with a neighborhood graph from the tree point clouds, the method treats the root point of the tree as a source point and determines an initial tree skeleton by using the Dijkstra algorithm. The initial skeleton lines are then optimized by adjusting line connectivity and branch nodes based on morphological characteristics of the tree. Finally, combined with the tree point clouds, the radius of each branch skeleton node is estimated and flat cones are used to simulate tree branches. A local triangulation method is used to connect the gaps between two joint flat cones. Demonstrated by street trees of different sizes and point densities, the proposed method can extract street tree skeletons effectively, generate tree models with higher fidelity, and reconstruct trees with different details according to the skeleton level. It is found out the tree modeling error is related to the average point spacing, with a maximum error at the coarsest level 6 being about 0.61 times the average point spacing. The main source of the modeling error is the self-occlusion of trees branches. Such findings are both theoretically and practically useful for generating high-precision tree models from point clouds. The developed method can be an alternative to the current ones that struggle to balance modeling efficiency and modeling accuracy.
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Mizunuma, M., S. Ogawa, C. Nishimura et H. Kuwano. « A Displacement Measurement Method by Laser-Beam Scanning for Mapping the Interior Geometry of Pipes ». Journal of Pressure Vessel Technology 116, no 2 (1 mai 1994) : 188–92. http://dx.doi.org/10.1115/1.2929574.
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This paper proposes a displacement measuring technique for detailed noncontact mapping of the interior geometry of pipes. The technique, which is based on optical measurement using triangulation, employs a laser-beam scanner to measure radial displacement. To achieve high precision, three different algorithms for calculating the displacement from sensor output are compared in experiments. One of them, which calculates the displacement by using several direction-dependent characteristic curves, gives high accuracy. The accuracy of our experimental system is ±0.2 mm for radii between 33 and 42 mm. A mapping system using this technique with automated data-acquisition and 3D rendering of the interior is also described. Its effectiveness is illustrated by the experimental results.
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Zhang, Suo Huai, Xu Meng et Wu Yong Wan. « A Non-Contact Method to Measure the Spatial Axis Position for Large-Scale Holes ». Applied Mechanics and Materials 239-240 (décembre 2012) : 739–43. http://dx.doi.org/10.4028/www.scientific.net/amm.239-240.739.
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Based on laser triangulation measuring principle, a non-contact precise measurement method is proposed to get the spatial axis position of the large hole parts. According to the method, the measurement system is designed and the measuring mathematical model is founded. The fitting curve of the scanning profile and the space equation of the central line are obtained by least squares method. Besides, the errors of the measurement system are analyzed and corrected. The spatial position of the central axis could be quickly obtained by the method.
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Rak, Gašper, Marko Hočevar, Sabina Kolbl Repinc, Lovrenc Novak et Benjamin Bizjan. « A Review on Methods for Measurement of Free Water Surface ». Sensors 23, no 4 (7 février 2023) : 1842. http://dx.doi.org/10.3390/s23041842.
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Turbulent free-surface flows are encountered in several engineering applications and are typically characterized by the entrainment of air bubbles due to intense mixing and surface deformation. The resulting complex multiphase structure of the air–water interface presents a challenge in precise and reliable measurements of the free-water-surface topography. Conventional methods by manometers, wave probes, point gauges or electromagnetic/ultrasonic devices are proven and reliable, but also time-consuming, with limited accuracy and are mostly intrusive. Accurate spatial and temporal measurements of complex three-dimensional free-surface flows in natural and man-made hydraulic structures are only viable by high-resolution non-contact methods, namely, LIDAR-based laser scanning, photogrammetric reconstruction from cameras with overlapping field of view, or laser triangulation that combines laser ranging with high-speed imaging data. In the absence of seeding particles and optical calibration targets, sufficient flow aeration is essential for the operation of both laser- and photogrammetry-based methods, with local aeration properties significantly affecting the measurement uncertainty of laser-based methods.
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Zhou, Yongquan, Songling Zhang, Shengyu Zhao et Huiqun Chen. « Computer Texture Mapping for Laser Texturing of Injection Mold ». Advances in Mechanical Engineering 6 (1 janvier 2014) : 681563. http://dx.doi.org/10.1155/2014/681563.
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Laser texturing is a relatively new multiprocess technique that has been used for machining 3D curved surfaces; it is more flexible and efficient to create decorative texture on 3D curved surfaces of injection molds so as to improve the surface quality and achieve cosmetic surface of molded plastic parts. In this paper, a novel method of laser texturing 3D curved surface based on 3-axis galvanometer scanning unit has been presented to prevent the texturing of injection mold surface from much distortion which is often caused by traditional texturing processes. The novel method has been based on the computer texture mapping technology which has been developed and presented. The developed texture mapping algorithm includes surface triangulation, notations, distortion measurement, control, and numerical method. An interface of computer texture mapping has been built to implement the algorithm of texture mapping approach to controlled distortion rate of 3D texture math model from 2D original texture applied to curvature surface. Through a case study of laser texturing of a high curvature surface of injection mold of a mice top case, it shows that the novel method of laser texturing meets the quality standard of laser texturing of injection mold.
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González-Collazo, S. M., J. Balado, E. González et M. Soilán. « ANALYSIS OF SUN GLARE ON ROUNDABOUTS WITH AERIAL LASER SCANNING DATA ». International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B2-2022 (30 mai 2022) : 1009–16. http://dx.doi.org/10.5194/isprs-archives-xliii-b2-2022-1009-2022.
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Abstract. Road geometry and sun glares play an important role concerning road safety. In this research, the direct sunlight in a roundabout sited in Ávila (Spain) is analysed using Aerial Laser Scanning (ALS) point clouds. First, the roundabout is divided in 8 sections, obtaining the driver bearing vectors of the roundabout. Entrances and exits driver bearing vectors of the roundabout are also considered. Then, sun rays are generated for a specific location of the roundabout and in a specific day and time. The incidence of the sun rays with the driver’s vision angle is analysed based on human vision model. Finally, intersections of sun rays with obstacles are calculated utilizing ALS point clouds. ALS data is processed (removing outliers, reducing point density, and computing a Delaunay Triangulation) in order to obtain accurate intersection results with obstacles and optimise the computational time. The method was tested in a roundabout, considering different driver bearings, the slope of the road and the elevation of the terrain. The results show that sun glares are detected at any day and time of the year, therefore areas with risk of direct sun glare within the roundabout are identified. The sun ray’s incidence in the vision angle of the driver is higher during winter solstice, and intersections with obstacles occur mainly during sunrise and sunset. In roundabout vector 7, during winter solstice there is direct sun glare for 7 hours 30 minutes, at the equinoxes for 6 hours 15 minutes and during summer solstice there is no direct sun glare.
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Meier, Nicolas, et Anthimos Georgiadis. « Optical Part Measuring inside a Milling Machine ». Key Engineering Materials 613 (mai 2014) : 440–45. http://dx.doi.org/10.4028/www.scientific.net/kem.613.440.
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The dimensions of a workpiece have been measured during the milling process using a 3D laser inspection system. Re-clamping of the work piece has been avoided but a short interruption of the milling process took place. All three dimensions of the part have been measured, height and width using a profile scanning devise based on the laser triangulation method and the length using also the displacement features of the machine tool. Gauge blocks with the reference dimension of 4, 8, 10, 14, 18 and 23 mm have been used for the verification of the measurements. The measured values for the height deviate from the real value between 0 to 19 μm. The deviations of the length lie between 0 and 33 μm. The deviations of the width are higher and they lie between 0 and 150 μm, because of the scanning steps of the devise. The measurement of the width could be improved using a second scanner perpendicular to the first one in order to achieve an overall part inspection with deviations lower than 33 μm.
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Boeckmans, Bart, Min Zhang, Frank Welkenhuyzen et Jean-Pierre Kruth. « Determination of Aspect Ratio Limitations, Accuracy and Repeatability of a Laser Line Scanning CMM Probe ». International Journal of Automation Technology 9, no 5 (5 septembre 2015) : 466–72. http://dx.doi.org/10.20965/ijat.2015.p0466.
Texte intégralRésumé :
Coordinate measurement machine (CMM) probing techniques can involve direct mechanical contact (e.g., tactile probing) or diverse non-contact principles (e.g., laser line scan probing). For some applications, contact methods are not capable of measuring fast enough to ensure 100% quality controlled parts. A laser line scanning probe uses a laser triangulation-based method to acquire 3D measurement points on a workpiece relative to a sensor. Mounting the sensor in a 3D coordinate frame, e.g., in a CMM provides enough information to fully examine the workpiece. These techniques are most commonly exploited in medical industry and industries involving plate materials. A high data density and measurement speed are significant advantages when measuring free-form surfaces by laser line scanning, making the process much more time-efficient. However, high-precision geometrical features (such as cylinders, spheres, etc.) must be measured for locating and aligning the free-form shapes. The accuracy of the equipment therefore has to be assessed. Probe Maximum Permissible Error (MPEP) values below 10μm have been reported for cutting-edge laser line scanners. This paper compares the major influences on measurements on cylindrical features. First, the aspect-ratio limitations are considered by comparing two inherently different techniques. The stable inspection of reference features is important, while trying to maximize the spatial extent of the measured features. Second, the measurement method is analyzed in two ways: by using a limited sample of the features to increase stability and eliminate interference from neighboring features; by varying the number of scan tracks, which greatly affects the measurement time.
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Ivanova, Yoana. « Methods and means for digital transformation of physical objects ». Yearbook Telecommunications 7 (12 août 2021) : 83–89. http://dx.doi.org/10.33919/ytelecomm.20.7.10.
Texte intégralRésumé :
The research aims to present main methods of digital transformations of physical objects by the means for 3D modelling and 3D scanning. Emphasis is placed on the advantages of laser scanning and the nature of the triangulation methods on which it is based. It is explained how the reliability of the obtained results depends on the calibration process that precedes the 3D scanning of a physical object. Special attention is paid to the technical and software preparation that precedes the 3D scanning process. The practical research is realized using a physical object suitable in terms of construction, shape and size. For the digital transformations is purposefully chosen a real existing spherical robot, which serves as a basis for comparison in assessing the effectiveness of the described methods, as well as the quality and realism of the obtained digital models. The scientific and applied contributions are expressed in a comparative analysis of practical methods, which contains an algorithm of steps suitable for educational purposes for the implementation of the described work processes.
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González-Collazo, Silvia María, Pablo del Río-Barral, Jesús Balado et Elena González. « Detection of Direct Sun Glare on Drivers from Point Clouds ». Remote Sensing 14, no 6 (18 mars 2022) : 1456. http://dx.doi.org/10.3390/rs14061456.
Texte intégralRésumé :
Sunlight conditions can reduce drivers’ visibility, which is a safety concern on road networks. This research introduces a method to study sun glare incidence in road environments. Sun glare areas during daylight hours are automatically detected from mobile laser scanning (MLS) and aerial laser scanning (ALS) point clouds. The method comprises the following steps. First, the Sun’s position (solar altitude and azimuth) referring to a location is calculated. Second, the incidence of sun glare with the user’s angle of vision is analyzed based on human vision. Third, sun ray intersections with near obstacles (vegetation, building, etc.) are calculated utilizing MLS point clouds. Finally, intersections with distant obstacles (mountains) are calculated utilizing ALS point clouds. MLS and ALS data are processed in order to combine both data types, remove outliers, and optimize computational time for intersection searches (point density reduction and Delaunay triangulation). The method was tested on two real case studies, covering roads with different bearings, slopes, and surroundings. The combination of MLS and ALS data, together with the solar geometry, identify areas of risk for the visibility of drivers. Consequently, the proposed method can be utilized to reduce sun glare, implementing warnings in navigation systems.
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Liu, Hai Jun, Ren Ke Kang, Shang Gao, Ping Zhou, Yu Tong et Dong Ming Guo. « Development of a Measuring Equipment for Silicon Wafer Warp ». Advanced Materials Research 797 (septembre 2013) : 561–65. http://dx.doi.org/10.4028/www.scientific.net/amr.797.561.
Texte intégralRésumé :
Larger diameter wafers are used to decrease the cost of IC manufacturing and the wafer thickness is decreasing for form factor and thermal power dissipation considerations. The larger wafer requires a large scanning area to inspect the warp, and warp measurement of large and thin silicon wafers is greatly affected by the gravity-induced deflection. In this paper the gravity-induced deflection was calculated using finite element method by supporting the wafer horizontally with three steel balls. A laser displacement sensor based on triangulation principle was used to measure the warp and an air bearing stage was developed to achieve high straightness. The shape of the wafer was obtained using the silicon wafer warp measuring equipment.
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Töberg, Stefan, et Eduard Reithmeier. « Quantitative 3D Reconstruction from Scanning Electron Microscope Images Based on Affine Camera Models ». Sensors 20, no 12 (26 juin 2020) : 3598. http://dx.doi.org/10.3390/s20123598.
Texte intégralRésumé :
Scanning electron microscopes (SEMs) are versatile imaging devices for the micro- and nanoscale that find application in various disciplines such as the characterization of biological, mineral or mechanical specimen. Even though the specimen’s two-dimensional (2D) properties are provided by the acquired images, detailed morphological characterizations require knowledge about the three-dimensional (3D) surface structure. To overcome this limitation, a reconstruction routine is presented that allows the quantitative depth reconstruction from SEM image sequences. Based on the SEM’s imaging properties that can be well described by an affine camera, the proposed algorithms rely on the use of affine epipolar geometry, self-calibration via factorization and triangulation from dense correspondences. To yield the highest robustness and accuracy, different sub-models of the affine camera are applied to the SEM images and the obtained results are directly compared to confocal laser scanning microscope (CLSM) measurements to identify the ideal parametrization and underlying algorithms. To solve the rectification problem for stereo-pair images of an affine camera so that dense matching algorithms can be applied, existing approaches are adapted and extended to further enhance the yielded results. The evaluations of this study allow to specify the applicability of the affine camera models to SEM images and what accuracies can be expected for reconstruction routines based on self-calibration and dense matching algorithms.
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Hussnain, Z., S. Oude Elberink et G. Vosselman. « AN AUTOMATIC PROCEDURE FOR MOBILE LASER SCANNING PLATFORM 6DOF TRAJECTORY ADJUSTMENT ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-1 (26 septembre 2018) : 203–9. http://dx.doi.org/10.5194/isprs-archives-xlii-1-203-2018.
Texte intégralRésumé :
<p><strong>Abstract.</strong> In this paper, a method is presented to improve the MLS platform’s trajectory for GNSS denied areas. The method comprises two major steps. The first step is based on a 2D image registration technique described in our previous publication. Internally, this registration technique first performs aerial to aerial image matching, this issues correspondences which enable to compute the 3D tie points by multiview triangulation. Similarly, it registers the rasterized Mobile Laser Scanning Point Cloud (MLSPC) patches with the multiple related aerial image patches. The later registration provides the correspondence between the aerial to aerial tie points and the MLSPC’s 3D points. In the second step, which is described in this paper, a procedure utilizes three kinds of observations to improve the MLS platform’s trajectory. The first type of observation is the set of 3D tie points computed automatically in the previous step (and are already available), the second type of observation is based on IMU readings and the third type of observation is soft-constraint over related pose parameters. In this situation, the 3D tie points are considered accurate and precise observations, since they provide both locally and globally strict constraints, whereas the IMU observations and soft-constraints only provide locally precise constraints. For 6DOF trajectory representation, first, the pose [R, t] parameters are converted to 6 B-spline functions over time. Then for the trajectory adjustment, the coefficients of B-splines are updated from the established observations. We tested our method on an MLS data set acquired at a test area in Rotterdam, and verified the trajectory improvement by evaluation with independently and manually measured GCPs. After the adjustment, the trajectory has achieved the accuracy of RMSE X<span class="thinspace"></span>=<span class="thinspace"></span>9<span class="thinspace"></span>cm, Y<span class="thinspace"></span>=<span class="thinspace"></span>14<span class="thinspace"></span>cm and Z<span class="thinspace"></span>=<span class="thinspace"></span>14<span class="thinspace"></span>cm. Analysing the error in the updated trajectory suggests that our procedure is effective at adjusting the 6DOF trajectory and to regenerate a reliable MLSPC product.</p>
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Komoriya, Kiyoshi, et Kazuo Tani. « Development of a Laser Range Sensor for a Mobile Robot ». Journal of Robotics and Mechatronics 3, no 5 (20 octobre 1991) : 373–78. http://dx.doi.org/10.20965/jrm.1991.p0373.
Texte intégralRésumé :
External sensors which can detect environmental information are important for a mobile robot to recognize its surroundings and location. Among external sensors, range sensors are fundamental because they can directly detect the free space in which the mobile robot can move without colliding with the surrounding objects. A laser range sensor provides good spatial resolution, and it is expected to detect characteristic parts of the environment used as landmarks for recognizing robot position. This paper presents the construction of a laser range sensor system which can be implemented in a small mobile robot. The system consists of several components including laser diode, CCD camera, and mark detection hardware. Based on triangulation method, the system can detect the distance to the object's surface on which the beam spot is directed. In order to detect a landmark, such as a wall edge, the sensor system is mounted on a rotary table. By horizontally scanning, the sensor can detect wall edges with an accuracy of approximately 5mm and an orientation accuracy of approximately 1 degree within 3m. This system has been installed in an indoor mobile robot and is used for autonomous navigation control along corridors.
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Díaz-Vilariño, L., E. Frías, J. Balado et H. González-Jorge. « SCAN PLANNING AND ROUTE OPTIMIZATION FOR CONTROL OF EXECUTION OF AS-DESIGNED BIM ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-4 (19 septembre 2018) : 143–48. http://dx.doi.org/10.5194/isprs-archives-xlii-4-143-2018.
Texte intégralRésumé :
<p><strong>Abstract.</strong> Scan-to-BIM systems have been recently proposed for the dimensional and quality assessment of as-built construction components with planned works. The procedure is generally based on the geometric alignment and comparison of as-built laser scans with as-designed BIM models. A major concern in Scan-to-BIM procedures is point cloud quality in terms of data completeness and consequently, the scanning process should be designed in order to obtain a full coverage of the scene while avoiding major occlusions. This work proposes a method to optimize the number and scan positions for Scan-to-BIM procedures following stop &amp; go scanning. The method is based on a visibility analysis using a <i>ray-tracing algorithm</i>. In addition, the optimal route between scan positions is formulated as a <i>travelling salesman problem</i> and solved using a suboptimal <i>ant colony optimization algorithm</i>. The distribution of candidate positions follows a grid-based structure, although other distributions based on triangulation or tessellation can be implemented to reduce the number of candidate positions and processing time.</p>
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Cuesta, Eduardo, Víctor Meana, Braulio J. Álvarez, Sara Giganto et Susana Martínez-Pellitero. « Metrology Benchmarking of 3D Scanning Sensors Using a Ceramic GD&T-Based Artefact ». Sensors 22, no 22 (8 novembre 2022) : 8596. http://dx.doi.org/10.3390/s22228596.
Texte intégralRésumé :
The use of non-contact scanning equipment in metrology and in dimensional and geometric inspection applications is increasing due to its ease of use, the speed and density of scans, and the current costs. In fact, these technologies are becoming increasingly dominant in the industrial environment, thus moving from reverse engineering applications to metrological applications. However, this planned transfer requires actions to ensure the achievable accuracy by providing traceability of measurements. In the present study, a comparison between the devices is carried out and a specific standard artefact is designed, equipped with multiple ceramic optically friendly entities, and allowing a wide variety of geometric dimensioning and tolerancing (GD&T). Four different 3D scanning sensors are used in the experimentation. Three of them are based on laser triangulation, and the fourth is a structured blue light sensor (fringe pattern projection). The standard artefact is calibrated with a high accuracy, using a coordinate measuring machine (CMM) and probing sensors. With this CMM, reference values of multiple predefined GD&T are obtained. The evaluation methodology maximises the accuracy of each device in measuring the dimensions of the artefact due to the good dimensional (milling and turning), surface (control of machining variables), and the dimensional and spatial distribution characteristics. The procedure also includes the same treatment of the captured point clouds (trimming, filtering, and best-fit algorithm, etc.) in each of the four 3D scanning sensors considered. From this process, very reliable measurements of the maximum achievable accuracy of each device (deviations from the CMM measurements) are finally obtained, and a multi-characteristic comparison between the four sensors is performed, also with high reliability.
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Kulawiak, Marek, et Zbigniew Łubniewski. « 3D Object Shape Reconstruction from Underwater Multibeam Data and Over Ground Lidar Scanning ». Polish Maritime Research 25, no 2 (1 juin 2018) : 47–56. http://dx.doi.org/10.2478/pomr-2018-0053.
Texte intégralRésumé :
Abstract The technologies of sonar and laser scanning are an efficient and widely used source of spatial information with regards to underwater and over ground environment respectively. The measurement data are usually available in the form of groups of separate points located irregularly in three-dimensional space, known as point clouds. This data model has known disadvantages, therefore in many applications a different form of representation, i.e. 3D surfaces composed of edges and facets, is preferred with respect to the terrain or seabed surface relief as well as various objects shape. In the paper, the authors propose a new approach to 3D shape reconstruction from both multibeam and LiDAR measurements. It is based on a multiple-step and to some extent adaptive process, in which the chosen set and sequence of particular stages may depend on a current type and characteristic features of the processed data. The processing scheme includes: 1) pre-processing which may include noise reduction, rasterization and pre-classification, 2) detection and separation of objects for dedicated processing (e.g. steep walls, masts), and 3) surface reconstruction in 3D by point cloud triangulation and with the aid of several dedicated procedures. The benefits of using the proposed methods, including algorithms for detecting various features and improving the regularity of the data structure, are presented and discussed. Several different shape reconstruction algorithms were tested in combination with the proposed data processing methods and the strengths and weaknesses of each algorithm were highlighted.
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Peterson, S., J. Lopez et R. Munjy. « COMPARISON OF UAV IMAGERY-DERIVED POINT CLOUD TO TERRESTRIAL LASER SCANNER POINT CLOUD ». ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences IV-2/W5 (29 mai 2019) : 149–55. http://dx.doi.org/10.5194/isprs-annals-iv-2-w5-149-2019.
Texte intégralRésumé :
<p><strong>Abstract.</strong> A small unmanned aerial vehicle (UAV) with survey-grade GNSS positioning is used to produce a point cloud for topographic mapping and 3D reconstruction. The objective of this study is to assess the accuracy of a UAV imagery-derived point cloud by comparing a point cloud generated by terrestrial laser scanning (TLS). Imagery was collected over a 320&thinsp;m by 320&thinsp;m area with undulating terrain, containing 80 ground control points. A SenseFly eBee Plus fixed-wing platform with PPK positioning with a 10.6&thinsp;mm focal length and a 20&thinsp;MP digital camera was used to fly the area. Pix4Dmapper, a computer vision based commercial software, was used to process a photogrammetric block, constrained by 5 GCPs while obtaining cm-level RMSE based on the remaining 75 checkpoints. Based on results of automatic aerial triangulation, a point cloud and digital surface model (DSM) (2.5&thinsp;cm/pixel) are generated and their accuracy assessed. A bias less than 1 pixel was observed in elevations from the UAV DSM at the checkpoints. 31 registered TLS scans made up a point cloud of the same area with an observed horizontal root mean square error (RMSE) of 0.006m, and negligible vertical RMSE. Comparisons were made between fitted planes of extracted roof features of 2 buildings and centreline profile comparison of a road in both UAV and TLS point clouds. Comparisons showed an average +8&thinsp;cm bias with UAV point cloud computing too high in two features. No bias was observed in the roof features of the southernmost building.</p>
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Zhou, Mingliang, Wen Cheng, Hongwei Huang et Jiayao Chen. « A Novel Approach to Automated 3D Spalling Defects Inspection in Railway Tunnel Linings Using Laser Intensity and Depth Information ». Sensors 21, no 17 (25 août 2021) : 5725. http://dx.doi.org/10.3390/s21175725.
Texte intégralRésumé :
The detection of concrete spalling is critical for tunnel inspectors to assess structural risks and guarantee the daily operation of the railway tunnel. However, traditional spalling detection methods mostly rely on visual inspection or camera images taken manually, which are inefficient and unreliable. In this study, an integrated approach based on laser intensity and depth features is proposed for the automated detection and quantification of concrete spalling. The Railway Tunnel Spalling Defects (RTSD) database, containing intensity images and depth images of the tunnel linings, is established via mobile laser scanning (MLS), and the Spalling Intensity Depurator Network (SIDNet) model is proposed for automatic extraction of the concrete spalling features. The proposed model is trained, validated and tested on the established RSTD dataset with impressive results. Comparison with several other spalling detection models shows that the proposed model performs better in terms of various indicators such as MPA (0.985) and MIoU (0.925). The extra depth information obtained from MLS allows for the accurate evaluation of the volume of detected spalling defects, which is beyond the reach of traditional methods. In addition, a triangulation mesh method is implemented to reconstruct the 3D tunnel lining model and visualize the 3D inspection results. As a result, a 3D inspection report can be outputted automatically containing quantified spalling defect information along with relevant spatial coordinates. The proposed approach has been conducted on several railway tunnels in Yunnan province, China and the experimental results have proved its validity and feasibility.
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Ostrowski, W., et K. Bakuła. « TOWARDS EFFICIENCY OF OBLIQUE IMAGES ORIENTATION ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-3/W4 (17 mars 2016) : 91–96. http://dx.doi.org/10.5194/isprsarchives-xl-3-w4-91-2016.
Texte intégralRésumé :
Many papers on both theoretical aspects of bundle adjustment of oblique images and new operators for detecting tie points on oblique images have been written. However, only a few achievements presented in the literature were practically implemented in commercial software. In consequence often aerial triangulation is performed either for nadir images obtained simultaneously with oblique photos or bundle adjustment for separate images captured in different directions. The aim of this study was to investigate how the orientation of oblique images can be carried out effectively in commercial software based on the structure from motion technology. The main objective of the research was to evaluate the impact of the orientation strategy on both duration of the process and accuracy of photogrammetric 3D products. Two, very popular software: Pix4D and Agisoft Photoscan were tested and two approaches for image blocks were considered. The first approach based only on oblique images collected in four directions and the second approach included nadir images. In this study, blocks for three test areas were analysed. Oblique images were collected with medium-format cameras in maltan cross configuration with registration of GNSS and INS data. As a reference both check points and digital surface models from airborne laser scanning were used.
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Ostrowski, W., et K. Bakuła. « TOWARDS EFFICIENCY OF OBLIQUE IMAGES ORIENTATION ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-3/W4 (17 mars 2016) : 91–96. http://dx.doi.org/10.5194/isprs-archives-xl-3-w4-91-2016.
Texte intégralRésumé :
Many papers on both theoretical aspects of bundle adjustment of oblique images and new operators for detecting tie points on oblique images have been written. However, only a few achievements presented in the literature were practically implemented in commercial software. In consequence often aerial triangulation is performed either for nadir images obtained simultaneously with oblique photos or bundle adjustment for separate images captured in different directions. The aim of this study was to investigate how the orientation of oblique images can be carried out effectively in commercial software based on the structure from motion technology. The main objective of the research was to evaluate the impact of the orientation strategy on both duration of the process and accuracy of photogrammetric 3D products. Two, very popular software: Pix4D and Agisoft Photoscan were tested and two approaches for image blocks were considered. The first approach based only on oblique images collected in four directions and the second approach included nadir images. In this study, blocks for three test areas were analysed. Oblique images were collected with medium-format cameras in maltan cross configuration with registration of GNSS and INS data. As a reference both check points and digital surface models from airborne laser scanning were used.
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Lari, Z., et N. El-Sheimy. « A NEW APPROACH FOR PROGRESSIVE DENSE RECONSTRUCTION FROM CONSECUTIVE IMAGES BASED ON PRIOR LOW-DENSITY 3D POINT CLOUDS ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W7 (13 septembre 2017) : 773–78. http://dx.doi.org/10.5194/isprs-archives-xlii-2-w7-773-2017.
Texte intégralRésumé :
In recent years, the increasing incidence of climate-related disasters has tremendously affected our environment. In order to effectively manage and reduce dramatic impacts of such events, the development of timely disaster management plans is essential. Since these disasters are spatial phenomena, timely provision of geospatial information is crucial for effective development of response and management plans. Due to inaccessibility of the affected areas and limited budget of first-responders, timely acquisition of the required geospatial data for these applications is usually possible only using low-cost imaging and georefencing sensors mounted on unmanned platforms. Despite rapid collection of the required data using these systems, available processing techniques are not yet capable of delivering geospatial information to responders and decision makers in a timely manner. To address this issue, this paper introduces a new technique for dense 3D reconstruction of the affected scenes which can deliver and improve the needed geospatial information incrementally. This approach is implemented based on prior 3D knowledge of the scene and employs computationally-efficient 2D triangulation, feature descriptor, feature matching and point verification techniques to optimize and speed up 3D dense scene reconstruction procedure. To verify the feasibility and computational efficiency of the proposed approach, an experiment using a set of consecutive images collected onboard a UAV platform and prior low-density airborne laser scanning over the same area is conducted and step by step results are provided. A comparative analysis of the proposed approach and an available image-based dense reconstruction technique is also conducted to prove the computational efficiency and competency of this technique for delivering geospatial information with pre-specified accuracy.
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Ye, L., et B. Wu. « PHOTOGRAMMETRIC POINT CLOUDS GENERATION IN URBAN AREAS FROM INTEGRATED IMAGE MATCHING AND SEGMENTATION ». ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences IV-2/W4 (13 septembre 2017) : 279–85. http://dx.doi.org/10.5194/isprs-annals-iv-2-w4-279-2017.
Texte intégralRésumé :
High-resolution imagery is an attractive option for surveying and mapping applications due to the advantages of high quality imaging, short revisit time, and lower cost. Automated reliable and dense image matching is essential for photogrammetric 3D data derivation. Such matching, in urban areas, however, is extremely difficult, owing to the complexity of urban textures and severe occlusion problems on the images caused by tall buildings. Aimed at exploiting high-resolution imagery for 3D urban modelling applications, this paper presents an integrated image matching and segmentation approach for reliable dense matching of high-resolution imagery in urban areas. The approach is based on the framework of our existing self-adaptive triangulation constrained image matching (SATM), but incorporates three novel aspects to tackle the image matching difficulties in urban areas: 1) occlusion filtering based on image segmentation, 2) segment-adaptive similarity correlation to reduce the similarity ambiguity, 3) improved dense matching propagation to provide more reliable matches in urban areas. Experimental analyses were conducted using aerial images of Vaihingen, Germany and high-resolution satellite images in Hong Kong. The photogrammetric point clouds were generated, from which digital surface models (DSMs) were derived. They were compared with the corresponding airborne laser scanning data and the DSMs generated from the Semi-Global matching (SGM) method. The experimental results show that the proposed approach is able to produce dense and reliable matches comparable to SGM in flat areas, while for densely built-up areas, the proposed method performs better than SGM. The proposed method offers an alternative solution for 3D surface reconstruction in urban areas.
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Craciun, D., A. Serna Morales, J. E. Deschaud, B. Marcotegui et F. Goulette. « Scalable and Detail-Preserving Ground Surface Reconstruction from Large 3D Point Clouds Acquired by Mobile Mapping Systems ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-3 (11 août 2014) : 73–80. http://dx.doi.org/10.5194/isprsarchives-xl-3-73-2014.
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The currently existing mobile mapping systems equipped with active 3D sensors allow to acquire the environment with high sampling rates at high vehicle velocities. While providing an effective solution for environment sensing over large scale distances, such acquisition provides only a discrete representation of the geometry. Thus, a continuous map of the underlying surface must be built. Mobile acquisition introduces several constraints for the state-of-the-art surface reconstruction algorithms. Smoothing becomes a difficult task for recovering sharp depth features while avoiding mesh shrinkage. In addition, interpolation-based techniques are not suitable for noisy datasets acquired by Mobile Laser Scanning (MLS) systems. Furthermore, scalability is a major concern for enabling real-time rendering over large scale distances while preserving geometric details. This paper presents a fully automatic ground surface reconstruction framework capable to deal with the aforementioned constraints. The proposed method exploits the quasi-flat geometry of the ground throughout a morphological segmentation algorithm. Then, a planar Delaunay triangulation is applied in order to reconstruct the ground surface. A smoothing procedure eliminates high frequency peaks, while preserving geometric details in order to provide a regular ground surface. Finally, a decimation step is applied in order to cope with scalability constraints over large scale distances. Experimental results on real data acquired in large urban environments are presented and a performance evaluation with respect to ground truth measurements demonstrate the effectiveness of our method.
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Bondar, Maxim N., Vladimir N. Legkiy et Igor S. Gibin. « SCANNING MEASURING SYSTEM BASED ON TRIANGULAR LASER RANGEFINDER ». Interexpo GEO-Siberia 8, no 2 (8 juillet 2020) : 113–19. http://dx.doi.org/10.33764/2618-981x-2020-8-2-113-119.
Texte intégralRésumé :
A scanning laser range finder that provides distance measurement up to 10 m with an accuracy of 0.01 m for 360-degree circular scanning of space is described. Using the triangulation principle with a multi-element photodetector allows to creating a small-sized laser measuring system for robotic platforms for industrial and special purposes. Using the microcontroller allows to rationally implementing the discrete algorithm of the system in a given sector of space.
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Kuschk, G., P. d'Angelo, R. Qin, D. Poli, P. Reinartz et D. Cremers. « DSM Accuracy Evaluation for the ISPRS Commission I Image Matching Benchmark ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-1 (7 novembre 2014) : 195–200. http://dx.doi.org/10.5194/isprsarchives-xl-1-195-2014.
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To improve the quality of algorithms for automatic generation of Digital Surface Models (DSM) from optical stereo data in the remote sensing community, the Working Group 4 of Commission I: Geometric and Radiometric Modeling of Optical Airborne and Spaceborne Sensors provides on its website <a href="http://www2.isprs.org/commissions/comm1/wg4/benchmark-test.html"target="_blank">http://www2.isprs.org/commissions/comm1/wg4/benchmark-test.html</a> a benchmark dataset for measuring and comparing the accuracy of dense stereo algorithms. The data provided consists of several optical spaceborne stereo images together with ground truth data produced by aerial laser scanning. In this paper we present our latest work on this benchmark, based upon previous work. <br><br> As a first point, we noticed that providing the abovementioned test data as geo-referenced satellite images together with their corresponding RPC camera model seems too high a burden for being used widely by other researchers, as a considerable effort still has to be made to integrate the test datas camera model into the researchers local stereo reconstruction framework. To bypass this problem, we now also provide additional rectified input images, which enable stereo algorithms to work out of the box without the need for implementing special camera models. Care was taken to minimize the errors resulting from the rectification transformation and the involved image resampling. <br><br> We further improved the robustness of the evaluation method against errors in the orientation of the satellite images (with respect to the LiDAR ground truth). To this end we implemented a point cloud alignment of the DSM and the LiDAR reference points using an Iterative Closest Point (ICP) algorithm and an estimation of the best fitting transformation. This way, we concentrate on the errors from the stereo reconstruction and make sure that the result is not biased by errors in the absolute orientation of the satellite images. The evaluation of the stereo algorithms is done by triangulating the resulting (filled) DSMs and computing for each LiDAR point the nearest Euclidean distance to the DSM surface. We implemented an adaptive triangulation method minimizing the second order derivative of the surface in a local neighborhood, which captures the real surface more accurate than a fixed triangulation. As a further advantage, using our point-to-surface evaluation, we are also able to evaluate non-uniformly sampled DSMs or triangulated 3D models in general. The latter is for example needed when evaluating building extraction and data reduction algorithms. <br><br> As practical example we compare results from three different matching methods applied to the data available within the benchmark data sets. These results are analyzed using the above mentioned methodology and show advantages and disadvantages of the different methods, also depending on the land cover classes.
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Xi, X., C. Wang, Y. P. Wan et K. N. Khuon. « Ta Keo Temple Reconstruction Based on Terrestrial Laser Scanning Technology ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-5/W7 (13 août 2015) : 449–52. http://dx.doi.org/10.5194/isprsarchives-xl-5-w7-449-2015.
Texte intégralRésumé :
Ta Keo temple is one of the very famous temple complex of Angkor Wat in northwestern Cambodia. It has been suffering massive collapse and other serious damages in recent years. Nowadays, Terrestrial Laser Scanning(TLS) technology is considered as a wellestablished resource for heritage documentation and protection (Lerma et al, 2008; Reshetyuk, 2009). This paper used TLS to reconstruct Ta Keo Temple. Firstly, we acquired 71 scanning stations of points cloud data with high density and high accuracy, and over one thousand images with high spatial resolution about the temple. Secondly, the raw points cloud data were denoised, reduced and managed efficiently, and registrated using an adjusted ICP algorithm. Thirdly, a triangulation method was used to model most objects. At last, we mapped the texture data into the digital model and a 3-D model of Ta Keo with high accuracy was achieved. The authors focus on large object reconstruction by TLS technology, and pay much attention to the scanning design, multi-station data and the whole project’s data registration, and texture mapping and so on. The research result will be useful for Ta Keo restoration, reconstruction and protection. Also, it is a good reference source for large complex buildings reconstruction when using terrestrial laser scanning technology.
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Jiang, Tianen, Xiaojun Lin, Liang Fang, Tianyu Yao, Yuzhen Zhao et Zheng Wei. « Research on Fitting Algorithm of Scattered Point Cloud Based on 3D Laser Scanning ». Mobile Information Systems 2022 (28 septembre 2022) : 1–11. http://dx.doi.org/10.1155/2022/8432308.
Texte intégralRésumé :
3D laser scanning equipment is an important equipment for reverse engineering. It is used as an information sensing device for the Industrial IoT. After analyzing and processing the measured data, it can issue construction instructions to equipment such as TBMs and shotcrete manipulator. It can be used to solve the problems of initial support contour detection, flatness detection, monitoring measurement, and so on in tunnel engineering. This paper considers that 3D laser scanning point cloud is a scattered point cloud and cannot be used directly. In order to extract the point cloud information as much as possible, it is necessary to fit the point cloud obtained by scanning first. This paper uses the triangulation method, the Poisson reconstruction method, and the Lagrange method, etc. to fit the scattered point cloud, analyzes the advantages and disadvantages of several fitting methods, and analyzes the accuracy of the surfaces generated by several fitting methods. This creates conditions for the subsequent utilization of the tunnel 3D laser scanning point cloud.
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Denkena, Berend, Marcel Wichmann, Klaas Maximilian Heide et René Räker. « Laser Scanning Based Object Detection to Realize Digital Blank Shadows for Autonomous Process Planning in Machining ». Journal of Manufacturing and Materials Processing 6, no 1 (22 décembre 2021) : 1. http://dx.doi.org/10.3390/jmmp6010001.
Texte intégralRésumé :
The automated process chain of an unmanned production system is a distinct challenge in the technical state of the art. In particular, accurate and fast raw-part recognition is a current problem in small-batch production. This publication proposes a method for automatic optical raw-part detection to generate a digital blank shadow, which is applied for adapted CAD/CAM (computer-aided design/computer-aided manufacturing) planning. Thereby, a laser-triangulation sensor is integrated into the machine tool. For an automatic raw-part detection and a workpiece origin definition, a dedicated algorithm for creating a digital blank shadow is introduced. The algorithm generates adaptive scan paths, merges laser lines and machine axis data, filters interference signals, and identifies part edges and surfaces according to a point cloud. Furthermore, a dedicated software system is introduced to investigate the created approach. This method is integrated into a CAD/CAM system, with customized software libraries for communication with the CNC (computer numerical control) machine. The results of this study show that the applied method can identify the positions, dimensions, and shapes of different raw parts autonomously, with deviations less than 1 mm, in 2.5 min. Moreover, the measurement and process data can be transferred without errors to different hardware and software systems. It was found that the proposed approach can be applied for rough raw-part detection, and in combination with a touch probe for accurate detection.