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Evaluation of Factors, Influencing the Accuracy of the Digital Model, Obtained by Laser Scanning
摘要： Measurements in terrestrial laser scanning (TLS) are not perfect and are subject to errors caused by various factors affecting the quality of the capture process and the resulting final product. Careful consideration of all these factors and errors provides a good basis for assessing the quality of the data and the information received. The accuracy of the 3D model obtained from laser scanning is influenced by the density of the measurements and the modelling methods. 3D modelling algorithms allow accuracy to be improved, but modelling software cannot solve all the problems, and it is impossible to achieve high quality 3D modelling without taking into account the factors that affect the accuracy of the measurements. The investigation of error sources in TLS measurements is rather complicated due to the large number of influencing factors that are interconnected. In addition to angular and longitudinal measurements, most scanning systems also offer a measure of the intensity of the reflected signal. Because the TLS is a non-reflective geodetic technology, it means that the measurement results are highly dependent on the reflectivity of the materials. The energy of the reflected signal depends on the following physical factors: object material properties, surface colour of the object, surface temperature, surface humidity, illumination. From the experimental studies it has been confirmed that the illumination and humidity of the scanned surfaces have a significant impact on their reflecting ability and the density of the received point cloud. Evaluation of digital model accuracy is made with а plane approximation and comparison with control points. Areas with different point densities were created in order to analyse the accuracy of 3D model and to determine the optimum scanning density.
关键词： accuracy,illumination,humidity,terrestrial laser scanning,TLS,point cloud,3D model,reflectivity
更新于2025-09-16 10:30:52
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A Case Study of UAS Borne Laser Scanning for Measurement of Tree Stem Diameter
摘要： Diameter at breast height (DBH) is one of the most important parameter in forestry. With increasing use of terrestrial and airborne laser scanning in forestry, new exceeding possibilities to directly derive DBH emerge. In particular, high resolution point clouds from laser scanners on board unmanned aerial systems (UAS) are becoming available over forest areas. In this case study, DBH estimation from a UAS point cloud based on modeling the relevant part of the tree stem with a cylinder, is analyzed with respect to accuracy and completeness. As reference, manually measured DBHs and DBHs from terrestrial laser scanning point clouds are used for comparison. We demonstrate that accuracy and completeness of the cylinder fit are depending on the stem diameter. Stems with DBH > 20 cm feature almost 100% successful reconstruction with relative differences to the reference DBH of 9% (DBH 20–30 cm) down to 1.8% for DBH > 40 cm.
关键词： forest inventory,cylinder,diameter at breast height,forestry,point cloud,Unmanned Aerial Systems,LiDAR,DBH
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE International Conference on Mechatronics and Automation (ICMA) - Tianjin, China (2019.8.4-2019.8.7)] 2019 IEEE International Conference on Mechatronics and Automation (ICMA) - Research on 3D Reconstruction Method Based on Laser Rotation Scanning
摘要： A three-dimensional reconstruction algorithm based on line laser rotation scanning is proposed. The rotating platform vision measurement system is designed. The system calibration method consisting of laser, camera and turntable is studied. The axis-eye calibration algorithm is introduced to register the point cloud in the same coordinate. In the system, the camera driven by the turntable is rotated to scan the target object for three-dimensional measurement. The method can obtain the point cloud information of the object by linear laser rotation scanning, and further recover the geometric shape of the three-dimensional visible surface of the object, which not only meets the requirements of the three-dimensional reconstruction target, but also verifies the feasibility and effectiveness of the system.
关键词： rotating platform,camera calibration,feature point extraction,point cloud reconstruction,3d reconstruction
更新于2025-09-12 10:27:22
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[IEEE 2018 Signal Processing: Algorithms, Architectures, Arrangements, and Applications (SPA) - Poznan (2018.9.19-2018.9.21)] 2018 Signal Processing: Algorithms, Architectures, Arrangements, and Applications (SPA) - Programmatic Simulation of Laser Scanning Products
摘要： The technology of laser scanning is widely used for producing three-dimensional digital representations of geographic features. The measurement results are usually available in the form of 3D point clouds, which are often used as a transitional data model in various remote sensing applications. Unfortunately, while the costs of Light Detection And Ranging scanners have dropped significantly in recent years, they are still considered to be quite expensive for smaller institutions. In consequence, the process of 3D point cloud acquisition remains a difficult one, requiring investment not only in scanning equipment, but also time to operate it and process the obtained results. However, if the goal does not involve the 3D digitalization of a particular object, but instead the point clouds are required e.g. for testing reconstruction algorithms, in many cases such input data can be successfully substituted with the results of a simulated scanning process, which is far easier to accomplish. This paper presents a programmatic simulator which generates artificial scanning results from solid meshes provided by the user and saves them in the form of point cloud datasets.
关键词： 3D,Laser scanning,Point cloud,Simulation,LiDAR
更新于2025-09-12 10:27:22
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Deriving Individual-Tree Biomass from Effective Crown Data Generated by Terrestrial Laser Scanning
摘要： Biomass reflects the state of forest management and is critical for assessing forest benefits and carbon storage. The effective crown is the region above the lower limit of the forest crown that includes the maximum vertical distribution density of branches and leaves; this component plays an important role in tree growth. Adding the effective crown to biomass equations can enhance the accuracy of the derived biomass. Six sample plots in a larch plantation (ranging in area from 0.06 ha to 0.12 ha and in number of trees from 63 to 96) at the Mengjiagang forest farm in Huanan County, Jiamusi City, Heilongjiang Province, China, were analyzed in this study. Terrestrial laser scanning (TLS) was used to obtain three-dimensional point cloud data on the trees, from which crown parameters at different heights were extracted. These parameters were used to determine the position of the effective crown. Moreover, effective crown parameters were added to biomass equations with tree height as the sole variable to improve the accuracy of the derived individual-tree biomass estimates. The results showed that the minimum crown contact height was very similar to the effective crown height, and an increase in model accuracy was apparent (with R2 a increasing from 0.846 to 0.910 and root-mean-square error (RMSE) decreasing from 0.372 kg to 0.286 kg). The optimal model for deriving biomass included tree height, crown length from minimum contact height, crown height from minimum contact height, and crown surface area from minimum contact height. The novelty of the article is that it improves the fit of individual-tree biomass models by adding crown-related variables and investigates how the accuracy of biomass estimation can be enhanced by using remote sensing methods without obtaining diameter at breast height.
关键词： point cloud data,TLS,effective crown,biomass,crown parameters
更新于2025-09-12 10:27:22
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Three-dimensional point cloud data subtle feature extraction algorithm for laser scanning measurement of large-scale irregular surface in reverse engineering
摘要： In reverse engineering, feature extraction of point cloud data is a key process for the precision machining of the large-sacle complex workpieces. Because of the large numbers of the point cloud data and the difficult recognition of the complex feature, incomplete feature recognition will have a serious impact on the accuracy of the machining. Thus, this paper proposes a subtle feature extraction algorithm, which can be used for the laser scanning measurement of the large-scale irregular surface. First, the L1-median point is calculated as the center point of the neighborhood. Second, the k+1 neighbors are introduced to compute the feature description of the point cloud. Then, the feature is extracted by multi-threshold based on Poisson region growth algorithm. Last, the proposed algorithm is applied to feature extraction experiment of point cloud data for the large spherical crown workpiece. Compared with the traditional algorithms, the proposed algorithm not only can identify the subtle feature information quickly, but also can locate the weld position more accurately.
关键词： Point cloud data,Subtle feature extraction,L1-median,Reverse engineering
更新于2025-09-12 10:27:22
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Extrinsic calibration and kinematic modelling of a laser line triangulation sensor integrated in an intelligent fixture with 3 degrees of freedom
摘要： This article presents the kinematic modelling for the extrinsic calibration of a laser line profile sensor integrated in an intelligent fixture. It aims to characterize the real 3D shape of flexible parts when they are clamped to ensure suitable stiffness for machining processes, aiding to define the machining path to improve the precision of the process. This tool consists of two linear axes and a rotary axis (3 DOF) which enables scanning the area of the part to be processed automatically. In order to carry out the accuracy evaluation of the intelligent fixture, some methods present in the state of the art have been considered and compared. Moreover, in order to design and identify the most suitable calibration procedure a previous simulation process is carried out based on sensitivity analysis. To complete the study, a test piece has been scanned with the intelligent fixture and compared with an external metrological frame employed as a ground truth. In addition, a characterization of the geometric performance of the fixture's linear actuators is carried out to check the geometric performance and its influence on the extrinsic calibration process accuracy. The results of this article show the importance of performing simulation processes in order to define the best measurement scenario for extrinsic calibration. Besides, it demonstrates the influence of the method used to perform extrinsic calibration in order to obtain good precision in the measures, where the geometric performance of the drives have a decisive influence.
关键词： Point cloud processing,Kinematic modelling,Kinematic calibration,Inverse problem,Triangulation sensor
更新于2025-09-12 10:27:22
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A Novel Method for Digitalisation of Test Fields by Laser Scanning
摘要： In this article, a novel, media undisruptive method for the measurement of photogrammetric test fields using a laser tracker is presented. The new approach is precise and versatile in its application. It relies on image processing on the quasi continuous measurements of a hand-held laser scanner and laser tracker combination. The field of useful applications is large. In this article, we show the benefit in the field of camera calibration. Essential for highly accurate photogrammetric measurements is a careful calibration, since all cameras have optical distortions due to manufacturing processes of the lens. The calibration can be done by e.g. using a test field. In some cases, 3D coordinates of the control points are necessary. These coordinates are often determined by photogrammetry itself and tacheometric angle measurements in advance. A scale, e.g. a subtense bar, usually needs to be included which increases the measuring efforts. The method bases on the measured 3D point cloud of a test field. With this technique, not only the centers of all control points are accessible. Other geometric features can be chosen too. Since the point cloud consist of many single point measurements, every control point determination has already a high statistical redundancy. The 3D coordinates of every single control point are extracted from the point cloud, making an additional scale obsolete. Presently, the position accuracy is ≤ 50 μm (MPE), which is mainly limited by the laser scanner used in this article. The here-presented technique can be applied to all kinds of shapes, dimensions, materials, numbers and arrangements of control points. Furthermore, it is a lot faster and easier to handle than the angle measurements of the tacheometer.
关键词： Laser scanning,Photogrammetric calibration,Test field,Geometric calibration,3D point cloud
更新于2025-09-12 10:27:22
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Metro gauge inspection system based on mobile laser scanning technology
摘要： Detecting metro gauge is very important for the safe operation of the subway. In this study, we design a low-cost metro tunnel mobile scanning system (MDS-TJ-1), which integrates a laser profile scanner with an inertial measure unit and an odometer to provide positioning and attitude parameters of the trajectory. The Lagrange interpolation is used to accomplish the time unification of different sensors. A dynamic alignment scheme for profile scanner is proposed based on the designed plane reflector target with high reflectivity. The error accumulation of the odometer is corrected by recognising the tunnel longitudinal joints, and finish the multi-source data fusion. The horizontal ray method is developed to process the metro gauge inspection. The experiment results show that the alignment accuracy of scanner is within 8 mm, the inner coincidence of the point cloud is within 3 cm, and the average error of the gauge inspection is 7.8 mm.
关键词： Alignment,Data fusion,Gauge inspection,Point cloud,Mobile laser scanning,Metro tunnel,Multi-sensors
更新于2025-09-12 10:27:22
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AdTree: Accurate, Detailed, and Automatic Modelling of Laser-Scanned Trees
摘要： Laser scanning is an effective tool for acquiring geometric attributes of trees and vegetation, which lays a solid foundation for 3-dimensional tree modelling. Existing studies on tree modelling from laser scanning data are vast. However, some works cannot guarantee sufficient modelling accuracy, while some other works are mainly rule-based and therefore highly depend on user inputs. In this paper, we propose a novel method to accurately and automatically reconstruct detailed 3D tree models from laser scans. We first extract an initial tree skeleton from the input point cloud by establishing a minimum spanning tree using the Dijkstra shortest-path algorithm. Then, the initial tree skeleton is pruned by iteratively removing redundant components. After that, an optimization-based approach is performed to fit a sequence of cylinders to approximate the geometry of the tree branches. Experiments on various types of trees from different data sources demonstrate the effectiveness and robustness of our method. The overall fitting error (i.e., the distance between the input points and the output model) is less than 10 cm. The reconstructed tree models can be further applied in the precise estimation of tree attributes, urban landscape visualization, etc. The source code of this work is freely available at https://github.com/tudelft3d/adtree.
关键词： point cloud,precision forestry,laser scanning,tree modelling
更新于2025-09-11 14:15:04