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1
Kamgar-Parsi, B., e B. Kamgar-Parsi. "Algorithms for matching 3d line sets". IEEE Transactions on Pattern Analysis and Machine Intelligence 26, n. 5 (maggio 2004): 582–93. http://dx.doi.org/10.1109/tpami.2004.1273930.
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Günther, Tobias, Christian Rössl e Holger Theisel. "Hierarchical opacity optimization for sets of 3D line fields". Computer Graphics Forum 33, n. 2 (maggio 2014): 507–16. http://dx.doi.org/10.1111/cgf.12336.
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Kanzler, Mathias, Marc Rautenhaus e Rudiger Westermann. "A Voxel-Based Rendering Pipeline for Large 3D Line Sets". IEEE Transactions on Visualization and Computer Graphics 25, n. 7 (1 luglio 2019): 2378–91. http://dx.doi.org/10.1109/tvcg.2018.2834372.
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Kamgar-Parsi, B., e B. Kamgar-Parsi. "Matching sets of 3D line segments with application to polygonal arc matching". IEEE Transactions on Pattern Analysis and Machine Intelligence 19, n. 10 (1997): 1090–99. http://dx.doi.org/10.1109/34.625109.
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Zhou, M., K. Y. Li, J. H. Wang, C. R. Li, G. E. Teng, L. Ma, H. H. Wu et al. "AUTOMATIC EXTRACTION OF POWER LINES FROM UAV LIDAR POINT CLOUDS USING A NOVEL SPATIAL FEATURE". ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences IV-2/W7 (16 settembre 2019): 227–34. http://dx.doi.org/10.5194/isprs-annals-iv-2-w7-227-2019.
Abstract (sommario):
<p><strong>Abstract.</strong> UAV LiDAR systems have unique advantage in acquiring 3D geo-information of the targets and the expenses are very reasonable; therefore, they are capable of security inspection of high-voltage power lines. There are already several methods for power line extraction from LiDAR point cloud data. However, the existing methods either introduce classification errors during point cloud filtering, or occasionally unable to detect multiple power lines in vertical arrangement. This paper proposes and implements an automatic power line extraction method based on 3D spatial features. Different from the existing power line extraction methods, the proposed method processes the LiDAR point cloud data vertically, therefore, the possible location of the power line in point cloud data can be predicted without filtering. Next, segmentation is conducted on candidates of power line using 3D region growing method. Then, linear point sets are extracted by linear discriminant method in this paper. Finally, power lines are extracted from the candidate linear point sets based on extension and direction features. The effectiveness and feasibility of the proposed method were verified by real data of UAV LiDAR point cloud data in Sichuan, China. The average correct extraction rate of power line points is 98.18%.</p>
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Kurz, Franz, Seyed Azimi, Chun-Yu Sheu e Pablo d’Angelo. "Deep Learning Segmentation and 3D Reconstruction of Road Markings Using Multiview Aerial Imagery". ISPRS International Journal of Geo-Information 8, n. 1 (18 gennaio 2019): 47. http://dx.doi.org/10.3390/ijgi8010047.
Abstract (sommario):
The 3D information of road infrastructures is growing in importance with the development of autonomous driving. In this context, the exact 2D position of road markings as well as height information play an important role in, e.g., lane-accurate self-localization of autonomous vehicles. In this paper, the overall task is divided into an automatic segmentation followed by a refined 3D reconstruction. For the segmentation task, we applied a wavelet-enhanced fully convolutional network on multiview high-resolution aerial imagery. Based on the resulting 2D segments in the original images, we propose a successive workflow for the 3D reconstruction of road markings based on a least-squares line-fitting in multiview imagery. The 3D reconstruction exploits the line character of road markings with the aim to optimize the best 3D line location by minimizing the distance from its back projection to the detected 2D line in all the covering images. Results showed an improved IoU of the automatic road marking segmentation by exploiting the multiview character of the aerial images and a more accurate 3D reconstruction of the road surface compared to the semiglobal matching (SGM) algorithm. Further, the approach avoids the matching problem in non-textured image parts and is not limited to lines of finite length. In this paper, the approach is presented and validated on several aerial image data sets covering different scenarios like motorways and urban regions.
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Du, Xuan, Zong Bin Li e Guo Hui Zhang. "Optimization of Printed Circuit Board Assignment and Component Allocation in Assembly Line". Advanced Materials Research 97-101 (marzo 2010): 2455–58. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.2455.
Abstract (sommario):
The assembly optimization problem of multiple printed circuit board (PCB) tasks is analyzed, and an optimal model is formulated to balance the workload in decoupled PCB assembly line. Combined with polychromatic sets and genetic algorithm (GA), an integrated methodology is developed to solve the PCB assignment and component allocation simultaneously. Based on polychromatic sets theory, a 3D numerical contour matrix is presented to describe the characters of PCB, component and machine and the constraint of machine and process, and a constraint model is formulated. Constraint model guarantees that GA searches in the available solution space and simplify the calculation of fitness value and GA operation. Computational results indicate that the approach presented in this paper is useful and effective.
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Zhao, Weizhao, Myron D. Ginsberg e David W. Smith. "Three-Dimensional Quantitative Autoradiography by Disparity Analysis: Theory and Application to Image Averaging of Local Cerebral Glucose Utilization". Journal of Cerebral Blood Flow & Metabolism 15, n. 4 (luglio 1995): 552–65. http://dx.doi.org/10.1038/jcbfm.1995.69.
Abstract (sommario):
Traditional autoradiographic image analysis has been restricted to the two-dimensional assessment of local cerebral glucose utilization (LCMRglc) or blood flow in individual brains. It is advantageous, however, to generate an entire three-dimensional (3D) data set and to develop the ability to map replicate images derived from multiple studies into the same 3D space, so as to generate average and standard deviation images for the entire series. We have developed a novel method, termed “disparity analysis,” for the alignment and mapping of autoradiographic images. We present the theory of this method, which is based upon a linear affine model, to analyze point-to-point disparities in two images. The method is a direct one that estimates scaling, translation, and rotation parameters simultaneously. Disparity analysis is general and flexible and deals well with damaged or asymmetric sections. We applied this method to study LCMRglc in nine awake male Wistar rats by the [14C]2-deoxyglucose method. Brains were physically aligned in the anteroposterior axis and were sectioned subserially at 100-μm intervals. For each brain, coronal sections were aligned by disparity analysis. The nine brains were then registered in the z-axis with respect to a common coronal reference level (bregma + 0.7 mm). Eight of the nine brains were mapped into the remaining brain, which was designated the “template,” and aggregate 3D data sets were generated of the mean and standard deviation for the entire series. The averaged images retained the major anatomic features apparent in individual brains but with some defocusing. Internal anatomic features of the averaged brain were smooth, continuous, and readily identifiable on sections through the 3D stack. The fidelity of the internal architecture of the averaged brain was compared with that of individual brains by analysis of line scans at four representative levels. Line scan comparisons between corresponding sections and their template showed a high degree of correlation, as did similar comparisons performed on entire sections. Fourier analysis of line scan data showed retention of low-frequency information with the expected attenuation of high-frequency components produced by averaging. Region-of-interest (ROI) analysis of the averaged brain yielded LCMRglc values virtually identical to those derived from measurements and subsequent averaging of data from individual brains. In summary, 3D reconstruction of averaged autoradiographic image data by disparity analysis is a feasible approach, which vastly simplifies ROI analysis, facilitates the assessment of hemodynamic or metabolic patterns in three dimensions, permits the computation of threshold-defined volumes of interest on averaged 3D data sets, makes possible atlas-based ROI strategies, and importantly provides the capability of generating 3D image data sets derived from arithmetic manipulations on two or more primary data sets (e.g., percent difference or ratio images).
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Lin, Li-Chieh J., Ray Y. Chuang, Chih-Heng Lu, Kuo-En Ching e Chien-Liang Chen. "Derivation of 3D Coseismic Displacement Field from Integrated Azimuth and LOS Displacements for the 2018 Hualien Earthquake". Remote Sensing 16, n. 7 (27 marzo 2024): 1159. http://dx.doi.org/10.3390/rs16071159.
Abstract (sommario):
A 3D surface deformation field for an earthquake can aid in understanding fault behaviors and earthquake mechanisms. However, SAR-based 3D surface deformation estimates are often limited by insufficient observations and hampered by various error sources. In this study, we demonstrate the derivation of a 3D coseismic displacement field from different InSAR processing algorithms. The azimuth displacements from Multiple Aperture Interferometry (MAI) and Pixel Offset Tracking (POT) were integrated to ensure reliable displacements at low coherent areas. The 3D displacement field was inverted pixel-by-pixel by Line-of-Sight (LOS) displacement and integrated azimuth displacement. The results showed that MAI and POT could compensate for the weaknesses of each algorithm. Also, pixels with less than three sets of observations showed higher noise levels. Such noisy pixels were removed by a denoising criterion proposed herein. For the vertical direction, the proportion of pixels inverted with two sets of azimuth and one set of LOS displacements was 26.1%. After denoising, the proportion dropped to 2.4% due to the insufficiency of LOS displacements. This shows that the viewing angle influences the overall performance of 3D surface displacement inversion. Implementing various displacement vectors should reduce such limitations.
10
An, Su-Yong, Lae-Kyoung Lee e Se-Young Oh. "Line segment-based fast 3D plane extraction using nodding 2D laser rangefinder". Robotica 33, n. 08 (1 maggio 2014): 1751–74. http://dx.doi.org/10.1017/s0263574714000927.
Abstract (sommario):
SUMMARYThree-dimensional (3D) data processing has applications in solving complex tasks such as object recognition, environment modeling, and robotic mapping and localization. Because using raw 3D data without preprocessing is very time-consuming, extraction of geometric features that describe the environment concisely is essential. In this sense, a plane can be a suitable geometric feature due to its simplicity of extraction and the abundance in indoor environments. This paper presents an online incremental plane extraction method using line segments for indoor environments. Our data collection system is based on a “nodding” laser scanner, so we exploit the incremental nature of its data acquisition in which physical rotation and 3D data processing are conducted in parallel. Line segments defined by two end points become supporting elements that comprise a plane, so a large proportion of scan points can be ignored once the line segments are extracted from each scan slice. This elimination of points reduces the algorithm complexity and computation time. Experiments with the tens of complete scan data sets which were acquired from a typical indoor environment demonstrated that our method was at least three times faster than the state-of-the-art methods.
11
Mashonkina, Lyudmila. "Review: progress in NLTE calculations and their application to large data-sets". Proceedings of the International Astronomical Union 9, S298 (maggio 2013): 355–65. http://dx.doi.org/10.1017/s174392131300656x.
Abstract (sommario):
AbstractOne of the major tasks in interpretation of data from large-scale stellar surveys is to determine the fundamental atmospheric parameters such as effective temperature, surface gravity, and metallicity. In most on-going and upcoming projects, they are derived spectroscopically, relying on classical one-dimensional (1D) model atmospheres and the assumption of LTE. This review discusses the present achievements and problems of non-local thermodynamic equilibrium (NLTE) line-formation calculations for FGK-type stars. The topics that are addressed include (i) the construction of comprehensive model atoms for the chemical elements with complex term system, (ii) possible systematic errors inherent in classical LTE spectroscopic determinations of stellar parameters and chemical abundances, (iii) the uncertainties in final NLTE results caused by the uncertainties in atomic data, and (iv) applications of the NLTE line-formation calculations coupled to the spatial and temporal average 〈3D〉 models to spectroscopic analyses.
12
JOUVET, N., M. A. BOUNOUAR, S. ECOFFEY, C. NAUENHEIM, A. BEAUMONT, S. MONFRAY, A. RUEDIGER, F. CALMON, A. SOUIFI e D. DROUIN. "RECENT DEVELOPMENTS ON 3D INTEGRATION OF METALLIC SET ONTO CMOS PROCESS FOR MEMORY APPLICATION". International Journal of Nanoscience 11, n. 04 (agosto 2012): 1240024. http://dx.doi.org/10.1142/s0219581x12400248.
Abstract (sommario):
This work presents a nanodamascene process for a CMOS back-end-of-line fabrication of metallic single electron transistor(SET), together with the use of simulation tools for the development of a SET SRAM memory cell. We show room temperature electrical characterizations of SETs fabricated on CMOS with relaxed dimensions, and simulations of a SET SRAM memory cell. Using their physical characteristics achievable through the use of atomic layer deposition, it will be demonstrated that it has the potential to operate at temperature up to 398 K, and that power consumption is less than that of equivalent circuit in advanced CMOS technologies. In order to take advantage of both low power SETs and high CMOS drive efficiency, a hybrid 3D SET CMOS circuit is proposed.
13
Cheng, Jun, Ming Cheng, Yan Bin Lin e Cheng Wang. "A Structure-Based Registration Method for Terrestrial Laser Scanning Data". Applied Mechanics and Materials 734 (febbraio 2015): 608–16. http://dx.doi.org/10.4028/www.scientific.net/amm.734.608.
Abstract (sommario):
This paper presents a novel structure-based registration method for terrestrial laser scanning (TLS) data. The line support region (LSR), which fits the 3D line segment, is adopted to describe the scene structure and reduce geometric complexity. Then we employ an evolution computation method to solve the optimization problem of global registration. Our method can be further enhanced by iterative closest points (ICP) or other local registration methods. We demonstrate the robustness of our algorithm on several point cloud sets with varying extent of overlap and degree of noise.
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Ismail, Rashad, Muhammad Javaid e Hassan Zafar. "Metric-Based Fractional Dimension of Rotationally-Symmetric Line Networks". Symmetry 15, n. 5 (12 maggio 2023): 1069. http://dx.doi.org/10.3390/sym15051069.
Abstract (sommario):
The parameter of distance plays an important role in studying the properties symmetric networks such as connectedness, diameter, vertex centrality and complexity. Particularly different metric-based fractional models are used in diverse fields of computer science such as integer programming, pattern recognition, and in robot navigation. In this manuscript, we have computed all the local resolving neighborhood sets and established sharp bounds of a metric-based fractional dimension called by the local fractional metric dimension of the rotationally symmetric line networks of wheel and prism networks. Furthermore, the bounded and unboundedness of these networks is also checked under local fractional metric dimension when the order of these networks approaches to infinity. The lower and upper bounds of local fractional metric dimension of all the rotationally symmetric line networks is also analyzed by using 3D shapes.
15
Hoegner, L., S. Tuttas, Y. Xu, K. Eder e U. Stilla. "EVALUATION OF METHODS FOR COREGISTRATION AND FUSION OF RPAS-BASED 3D POINT CLOUDS AND THERMAL INFRARED IMAGES". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B3 (9 giugno 2016): 241–46. http://dx.doi.org/10.5194/isprs-archives-xli-b3-241-2016.
Abstract (sommario):
This paper discusses the automatic coregistration and fusion of 3d point clouds generated from aerial image sequences and corresponding thermal infrared (TIR) images. Both RGB and TIR images have been taken from a RPAS platform with a predefined flight path where every RGB image has a corresponding TIR image taken from the same position and with the same orientation with respect to the accuracy of the RPAS system and the inertial measurement unit. To remove remaining differences in the exterior orientation, different strategies for coregistering RGB and TIR images are discussed: (i) coregistration based on 2D line segments for every single TIR image and the corresponding RGB image. This method implies a mainly planar scene to avoid mismatches; (ii) coregistration of both the dense 3D point clouds from RGB images and from TIR images by coregistering 2D image projections of both point clouds; (iii) coregistration based on 2D line segments in every single TIR image and 3D line segments extracted from intersections of planes fitted in the segmented dense 3D point cloud; (iv) coregistration of both the dense 3D point clouds from RGB images and from TIR images using both ICP and an adapted version based on corresponding segmented planes; (v) coregistration of both image sets based on point features. The quality is measured by comparing the differences of the back projection of homologous points in both corrected RGB and TIR images.
16
Hoegner, L., S. Tuttas, Y. Xu, K. Eder e U. Stilla. "EVALUATION OF METHODS FOR COREGISTRATION AND FUSION OF RPAS-BASED 3D POINT CLOUDS AND THERMAL INFRARED IMAGES". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B3 (9 giugno 2016): 241–46. http://dx.doi.org/10.5194/isprsarchives-xli-b3-241-2016.
Abstract (sommario):
This paper discusses the automatic coregistration and fusion of 3d point clouds generated from aerial image sequences and corresponding thermal infrared (TIR) images. Both RGB and TIR images have been taken from a RPAS platform with a predefined flight path where every RGB image has a corresponding TIR image taken from the same position and with the same orientation with respect to the accuracy of the RPAS system and the inertial measurement unit. To remove remaining differences in the exterior orientation, different strategies for coregistering RGB and TIR images are discussed: (i) coregistration based on 2D line segments for every single TIR image and the corresponding RGB image. This method implies a mainly planar scene to avoid mismatches; (ii) coregistration of both the dense 3D point clouds from RGB images and from TIR images by coregistering 2D image projections of both point clouds; (iii) coregistration based on 2D line segments in every single TIR image and 3D line segments extracted from intersections of planes fitted in the segmented dense 3D point cloud; (iv) coregistration of both the dense 3D point clouds from RGB images and from TIR images using both ICP and an adapted version based on corresponding segmented planes; (v) coregistration of both image sets based on point features. The quality is measured by comparing the differences of the back projection of homologous points in both corrected RGB and TIR images.
17
Hammad Mian, Syed, Mohammed Abdul Mannan e Abdulrahman M. Al-Ahmari. "The influence of surface topology on the quality of the point cloud data acquired with laser line scanning probe". Sensor Review 34, n. 3 (10 giugno 2014): 255–65. http://dx.doi.org/10.1108/sr-01-2013-611.
Abstract (sommario):
Purpose – The purpose of this paper is to investigate the influence of surface topology on the performance of laser line scanning probe and to suggest methodology for 3D digitization of specular surfaces. Design/methodology/approach – Two different molds, one having milled surface and the other with polished surface, were used to identify effect of surface characteristics on the performance of laser line scanning probe mounted on bridge-type coordinate measuring machine. The point cloud data acquisition of two surfaces was carried out using different combinations of laser scanning parameters. The point cloud sets thus obtained were analyzed in terms of completeness, noise and accuracy. The polished mold which exhibited specular reflection was digitized at different scanning angles of laser line scanning probe using the best combination of scanning parameters. Findings – Results confirmed that surface characteristics play important role to determine quality of the reverse engineering (RE) process. The results in terms of completeness, accuracy and noise for point cloud sets have successfully been obtained for milled and polished surfaces. Three-dimensional (3D) comparison analysis suggested larger deviation in cases of polished surface as compared to milled surface. The point cloud set acquired with proposed approach was better in terms of both completeness and noise reduction. Originality/value – There has been an increased demand for measurement of metallic, polished and shiny surfaces in automotive, aerospace and medical industries. These surfaces are very difficult to scan because they exhibit specular reflection instead of diffuse reflection. Laser line scanning probe which is a non-contact method is in great demand for RE. This is due to the fact that it possesses very high data acquisition speed. However, laser scanning is hugely affected by surface characteristics which in turn govern specular reflection.In this paper, it has been shown that a surface that exhibits various degrees of specular reflection can be digitized efficiently if appropriate combination of scanning parameters and positions of laser line scanning probe are used. Also, this paper has attempted to offer a procedure to overcome incompleteness and noise in 3D data as obtained by the laser line scanning probe.
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Li, Lin, Kelvin C. P. Wang, Qiang Li, Wenting Luo e Jiangang Guo. "Impacts of Sample Size on Calculation of Pavement Texture Indicators with 1mm 3D Surface Data". Periodica Polytechnica Transportation Engineering 46, n. 1 (4 settembre 2017): 42. http://dx.doi.org/10.3311/pptr.9587.
Abstract (sommario):
The emerging 1mm resolution 3D data collection technology is capable of covering the entire pavement surface, and provides more data sets than traditional line-of-sight data collection systems. As a result, quantifying the impact of sample size including sample width and sample length on the calculation of pavement texture indicators is becoming possible. In this study, 1mm 3D texture data are collected and processed at seven test sites using the PaveVision3D Ultra system. Analysis of Variance (ANOVA) test and linear regression models are developed to investigate various sample length and width on the calculation of three widely used texture indicators: Mean Profile Depth (MPD), Mean Texture Depth (MTD) and Power Spectra Density (PSD). Since the current ASTM standards and other procedures cannot be directly applied to 3D surface for production due to a lack of definitions, the results from this research are beneficial in the process to standardize texture indicators’ computations with 1mm 3D surface data of pavements.
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Li, Luping, Jian Chen, Xing Su e Ahsan Nawaz. "Advanced-Technological UAVs-Based Enhanced Reconstruction of Edges for Building Models". Buildings 12, n. 8 (15 agosto 2022): 1248. http://dx.doi.org/10.3390/buildings12081248.
Abstract (sommario):
Accurate building models are widely used in the construction industry in the digital era. UAV cameras combined with image-based reconstruction provide a low-cost technology for building modeling. Most existing reconstruction methods operate on point clouds, while massive points reduce computational efficiency, and the accumulated error of point position often distorts building edges. This paper introduces an innovative 3D reconstruction method, Edge3D, that recovers building edges in the form of 3D lines. It employs geometry constraints and progressive screening technology to improve the robustness and precision of line segment matching. An innovative bundle adjustment strategy based on endpoints is designed to reduce the global reprojection error. Edges were tested on challenging real-world image sets, and matching precisions of 96% and 94% were achieved on the two image sets, respectively, with good reconstruction results. The proposed approach reconstructs building edges using a small number of lines instead of massive points, which contributes to the rapid reconstruction of building contour construction and obtaining accurate models, serving as an important foundation for the promotion of construction advancement.
20
Li, Shengpu, e Yize Sun. "Predicting Ink Transfer Rate of 3D Additive Printing Using EGBO Optimized Least Squares Support Vector Machine Model". Mathematical Problems in Engineering 2020 (25 settembre 2020): 1–12. http://dx.doi.org/10.1155/2020/8642430.
Abstract (sommario):
Ink transfer rate (ITR) is a reference index to measure the quality of 3D additive printing. In this study, an ink transfer rate prediction model is proposed by applying the least squares support vector machine (LSSVM). In addition, enhanced garden balsam optimization (EGBO) is used for selection and optimization of hyperparameters that are embedded in the LSSVM model. 102 sets of experimental sample data have been collected from the production line to train and test the hybrid prediction model. Experimental results show that the coefficient of determination (R2) for the introduced model is equal to 0.8476, the root-mean-square error (RMSE) is 6.6 × 10 (−3), and the mean absolute percentage error (MAPE) is 1.6502 × 10 (−3) for the ink transfer rate of 3D additive printing.
21
Bentley, Laurence R., e Mehran Gharibi. "Two‐ and three‐dimensional electrical resistivity imaging at a heterogeneous remediation site". GEOPHYSICS 69, n. 3 (maggio 2004): 674–80. http://dx.doi.org/10.1190/1.1759453.
Abstract (sommario):
Geometrically complex heterogeneities at a decommissioned sour gas plant could not be adequately characterized with drilling and 2D electrical resistivity surveys alone. In addition, 2D electrical resistivity imaging profiles produced misleading images as a result of out‐of‐plane resistivity anomalies and violation of the 2D assumption. Accurate amplitude and positioning of electrical conductivity anomalies associated with the subsurface geochemical distribution were required to effectively analyze remediation alternatives. Forward and inverse modeling and field examples demonstrated that 3D resistivity images were needed to properly reconstruct the amplitude and geometry of the complex resistivity anomalies. Problematic 3D artifacts in 2D images led to poor inversion fits and spurious conductivity values in the images at depths close to the horizontal offset of the off‐line anomaly. Three‐dimensional surveys were conducted with orthogonal sets of Wenner and dipole–dipole 2D resistivity survey lines. The 3D inversions were used to locate source zones and zones of elevated ammonium. Thus, conducting 3D electrical resistivity imaging (ERI) surveys early in the site characterization process will improve cost effectiveness at many remediation sites.
22
Jia, Xin, Qing Zhu, Xuming Ge, Ruifeng Ma, Daiwei Zhang e Tao Liu. "Robust Guardrail Instantiation and Trajectory Optimization of Complex Highways Based on Mobile Laser Scanning Point Clouds". Photogrammetric Engineering & Remote Sensing 89, n. 3 (1 marzo 2023): 151–61. http://dx.doi.org/10.14358/pers.22-00100r2.
Abstract (sommario):
As a basic asset of highways, guardrails are essential objects in the digital modeling of highways. Therefore, generating the vectorial 3D trajectory of a guardrail from mobile laser scanning (MLS) point clouds is required for real digital modeling. However, most methods limit straight-line guardrails without considering the continuity and accuracy of the guardrails in turnoff and bend areas; thus, a completed 3D trajectory of a guardrail is not available. We use RANDLA-Net for extracting guardrails as preprocessing of MLS point clouds. We perform a region growth strategy based on linear constraints to obtain correct instantiations and a forward direction. The improved Douglas– Puke algorithm is used to simplify the center points of guardrail, and the 3D trajectory of every guardrail can be vectorized using cubic spline curve fitting. The proposed approach is validated on two 3-km case data sets that can completely instantiate MLS point clouds with remarkable effects. Quantitative evaluations demonstrate that the proposed guardrail instantiation algorithm achieves an overall precision and recall of 98.80% and 97.5%, respectively. The generated 3D trajectory can provide a high-precision design standard for the 3D modeling of the guardrail and has been applied to a long highway scene.
23
Roberge, Danny, Alain Beauchamp e Serge Lévesque. "Objective Identification of Bullets Based on 3D Pattern Matching and Line Counting Scores". International Journal of Pattern Recognition and Artificial Intelligence 33, n. 11 (ottobre 2019): 1940021. http://dx.doi.org/10.1142/s0218001419400214.
Abstract (sommario):
In firearm identification, a firearm examiner looks at a pair of fired bullets or cartridge cases using a comparison microscope and determines from this visual analysis if they were both fired from the same firearm. In the particular case of fired bullets, the individual firearm signature takes the form of a striated pattern. Over the time, the firearm examiner’s community developed two distinct approaches for bullet identification: pattern matching and line counting. More recently, the emergence of technology enabling the capture of surface topographies down to a submicron depth resolution has been a catalyst for the field of computerized objective ballistic identification. Objectiveness is achieved through the statistical analysis of various scores of known matches and known nonmatches exhibit pair comparison, which in turn implies the capture of large quantities of bullets and cartridge cases topographies. The main goal of this study was to develop an objective identification method for bullets fired from conventionally rifled barrels, and to test this method on public and proprietary bullet 3D image datasets captured at different lateral resolutions. Two newly developed bullet identification scores, the Line Counting Score (LCS) and the Pattern Matching Score, computed on 3D topographies yielded perfect match versus nonmatch separation for three different sets used in the standard Hamby–Brundage Test. A similar analysis performed using a larger, more-realistic set, enabled us to define a discriminative line at a false match rate of 1/10[Formula: see text]000 on a 2D plot that shows both identification scores for matches and nonmatches. The LCS is shown to produce a better sensitivity than the standard consecutive matching striae criteria for the more-realistic dataset. A likelihood function was also computed from a linear combination of both scores, and a conservative approach based on extreme value theory is proposed to extrapolate this function in the score domain where nonmatch data are not available. This study also provides a better understanding of the limitations of studies that involve very few firearms.
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Manzi, Musa S. D., Mark A. S. Gibson, Kim A. A. Hein, Nick King e Raymond J. Durrheim. "Application of 3D seismic techniques to evaluate ore resources in the West Wits Line goldfield and portions of the West Rand goldfield, South Africa". GEOPHYSICS 77, n. 5 (1 settembre 2012): WC163—WC171. http://dx.doi.org/10.1190/geo2012-0133.1.
Abstract (sommario):
As expensive as 3D seismic reflection surveys are, their high cost is justified by improved imaging of certain ore horizons in some of the Witwatersrand basin gold mines. The merged historical 3D seismic reflection data acquired for Kloof and South Deep mines forms an integral part of their Ventersdorp Contact Reef mine planning and development programme. The recent advances in 3D seismic technology have motivated the reprocessing and reinterpretation of the old data sets using the latest algorithms, therefore significantly increasing the signal-to-noise ratio of the data. In particular, the prestack time migration technique has provided better stratigraphic and structural imaging in complex faulted areas, such as the Witwatersrand basin, relative to older poststack migration methods. Interpretation tools such as seismic attributes have been used to identify a number of subtle geologic structures that have direct impact on ore resource evaluation. Other improvements include more accurate mapping of the depths, dip, and strike of the key seismic horizons and auriferous reefs, yielding a better understanding of the interrelationship between fault activity and reef distribution, and the relative chronology of tectonic events. The 3D seismic data, when integrated with underground mapping and borehole data, provide better imaging and modeling of critical major fault systems and zones of reef loss. Many faults resolve as multifault segments that bound unmined blocks leading to the discovery and delineation of resources in faulted areas of the mines.
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Tomás, R., A. Riquelme, M. Cano, J. L. Pastor, J. I. Pagán, J. L. Asensio e M. Ruffo. "Evaluación de la estabilidad de taludes rocosos a partir de nubes de puntos 3D obtenidas con un vehículo aéreo no tripulado". Revista de Teledetección, n. 55 (23 giugno 2020): 1. http://dx.doi.org/10.4995/raet.2020.13168.
Abstract (sommario):
<p>In this work, a methodology proposed for the semiautomatic identification of discontinuities and the later kinematic and stability analyses is described through its application to a rocky railway line cutting. Image acquisition has been performed using a six-rotors unmanned aerial vehicle for their subsequent photogrammetric restitution by means of the digital technique Structure from Motion (SfM) by means of the software Agisoft Metashape that provides a 3D point cloud. From this 3D point cloud, four discontinuity sets (J<sub>1</sub>, J<sub>2</sub>, J<sub>3</sub> and J<sub>4</sub>) affecting the cutting have been identified using the open source software Discontinuity Set Extractor (DSE). Finally, kinematic and stability analyses of the potential block failures controlled by the discontinuities identified in the cutting. The results show three potential wedge and planar failures that have been qualitatively validated trough the geometric analysis of the 3D point cloud.<em></em></p>
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Hua, Lisa L., e Takashi Mikawa. "Mitotic antipairing of homologous and sex chromosomes via spatial restriction of two haploid sets". Proceedings of the National Academy of Sciences 115, n. 52 (10 dicembre 2018): E12235—E12244. http://dx.doi.org/10.1073/pnas.1809583115.
Abstract (sommario):
Pairing homologous chromosomes is required for recombination. However, in nonmeiotic stages it can lead to detrimental consequences, such as allelic misregulation and genome instability, and is rare in human somatic cells. How mitotic recombination is prevented—and how genetic stability is maintained across daughter cells—is a fundamental, unanswered question. Here, we report that both human and mouse cells impede homologous chromosome pairing by keeping two haploid chromosome sets apart throughout mitosis. Four-dimensional analysis of chromosomes during cell division revealed that a haploid chromosome set resides on either side of a meridional plane, crossing two centrosomes. Simultaneous tracking of chromosome oscillation and the spindle axis, using fluorescent CENP-A and centrin1, respectively, demonstrates collective genome behavior/segregation of two haploid sets throughout mitosis. Using 3D chromosome imaging of a translocation mouse with a supernumerary chromosome, we found that this maternally derived chromosome is positioned by parental origin. These data, taken together, support the identity of haploid sets by parental origin. This haploid set-based antipairing motif is shared by multiple cell types, doubles in tetraploid cells, and is lost in a carcinoma cell line. The data support a mechanism of nuclear polarity that sequesters two haploid sets along a subcellular axis. This topological segregation of haploid sets revisits an old model/paradigm and provides implications for maintaining mitotic fidelity.
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Wang, Zhiheng, Rui Zhang e Yuxin Liu. "3D Coseismic Deformation Field and Source Parameters of the 2017 Iran-Iraq Mw7.3 Earthquake Inferred from DInSAR and MAI Measurements". Remote Sensing 11, n. 19 (27 settembre 2019): 2248. http://dx.doi.org/10.3390/rs11192248.
Abstract (sommario):
The coseismic slip on the main fault related to the 2017 Iran-Iraq Mw7.3 earthquake has been investigated by previous studies using DInSAR (differential interferometric synthetic aperture radar) ground deformation measurements. However, DInSAR observation is not sensitive to the ground deformation in the along-track (AT) direction. Therefore, only the one-dimensional (1D) DInSAR coseismic deformation field measurements, derived in the LOS (line-of-sight) direction of radar, was applied in source parameters estimation. To further improve the accuracy of the fault slip inversion, the 3D (three-dimensional) coseismic deformation fields were reconstructed in the first place, by a combined use of the DInSAR and MAI (multiple aperture InSAR) measurements. Subsequently, the LOS and 3D deformation data sets were used as the constraint respectively, to perform a two-step inversion scheme to find an optimal geometry and slip distribution on the main fault. The comparative analysis indicated that the 3D coseismic deformation data sets improved the inversion-accuracy by 30%. Besides, the fault invention results revealed a deep dislocation on a NNW trending fault (the strike is 352.63°) extending about 60 km, along the fault dips 14.76° to the ENE. The estimated seismic moment is 8.44 × 1019 Nm (Mw7.3), which is close to the solution provided by USGS (United States Geological Survey). The slip distributed at the depth between 12 and 18 km, and the peak slip of 6.53 m appears at the depth of 14.5 km left near the epicenter. Considering the geological structure in the earthquake region and fault source-parameters, it comes to a preliminary conclusion that the ZMFF (the Zagros Mountain Front fault) should be responsible for the earthquake. In general, this paper demonstrated the superiority of using the 3D coseismic deformation fields on source parameters estimation.
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Han, Tian, Davood Shojaei, Paul Fitzpatrick, Taka Sakurai e Jamie Evans. "Urban 5G MmWave Networks: Line-of-Sight Probabilities and Optimal Site Locations". Journal of Telecommunications and the Digital Economy 11, n. 1 (31 marzo 2023): 107–30. http://dx.doi.org/10.18080/jtde.v11n1.640.
Abstract (sommario):
In this work, we implemented line-of-sight (LoS) ray tracing functionality to investigate problems in millimetre-wave propagation modelling and network planning in 3D city model environments. First, we validated an existing LoS propagation probability model expressed as an exponential rule with the link distance. By fitting ray tracing simulation results under different scenarios to the model, the relationships between key parameters in the model and factors including the building density and the transmitter height were qualitatively analysed. Next, we developed a network planning framework for a multi-hop outdoor urban network by formulating a mixed-integer linear programming problem which minimises the overall deployment cost through optimal site selection. Taking the sets of potential site locations and potential links as inputs, we selected a subset of the sites that comprise a tree-structured network that satisfies all the user demands at a minimum deployment cost. We also analysed the time required for solving this optimisation problem in order to provide a prediction of the execution time for larger-sized problems.
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Martorana, Raffaele, e Patrizia Capizzi. "Evaluation of Artifacts and Misinterpretation in 2D Electrical Resistivity Tomography Caused by Three-Dimensional Resistive Structures of Regular or Irregular Shapes". Applied Sciences 13, n. 3 (3 febbraio 2023): 2015. http://dx.doi.org/10.3390/app13032015.
Abstract (sommario):
Electrical resistivity tomography (ERT) is a well-known geophysical method applied to geological, hydrogeological and geoenvironmental research. To date, 2D ERT is still used much more than 3D ERT, thanks to its greater immediacy, survey speed and lower complexity in processing and inversion. However, the assumption of two-dimensionality of the underground structures can mean that the effects of 3D structures on the 2D ERT can sometimes lead to gross errors in interpretation. This work aims to evaluate these effects by testing synthetic and experimental models. Numerical simulations are performed starting from different resistivity models, and from the results, 2D data sets are derived to study and quantify the effects of 2D inversion on 3D structures. Tests simulating prismatic resistive blocks with a vertical square section are presented. Prisms extend orthogonally to the survey line. Depending on their length, they range from a minimum equal to the length of the section (cubic resistive block) to infinity (2D prism). On these models, 2D and 3D electrical resistivity tomography (ERT) surveys are simulated. The results show that resistive blocks with a limited extension orthogonal to the profile are not effectively resolved by 2D ERT. Additionally, resistivity values obtained from a 2D ERT inversion on a 3D resistive prism are underestimated more than those obtained on the corresponding 2D prism when compared with the true value. This underestimation increases with the three-dimensional characteristics. Furthermore, resistive blocks located near the survey line but not crossed by it create artifacts that can lead to erroneous interpretations. A field test performed on a calcarenite quarry, of which the three-dimensional geophysical model was reconstructed, confirmed the results obtained by the synthetic tests, highlighting that the effects of three-dimensionality can lead to the identification of artifacts in the vertical section or produce strong errors in the estimation of depth and size, thus causing misleading statements.
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Ahmed, Naseer, Sankar Venkataraman, Kate Johnson, Keith Sutherland e Shaun K. Loewen. "Does Motion Assessment With 4-Dimensional Computed Tomographic Imaging for Non–Small Cell Lung Cancer Radiotherapy Improve Target Volume Coverage?" Clinical Medicine Insights: Oncology 11 (1 gennaio 2017): 117955491769846. http://dx.doi.org/10.1177/1179554917698461.
Abstract (sommario):
Introduction: Modern radiotherapy with 4-dimensional computed tomographic (4D-CT) image acquisition for non–small cell lung cancer (NSCLC) captures respiratory-mediated tumor motion to provide more accurate target delineation. This study compares conventional 3-dimensional (3D) conformal radiotherapy (3DCRT) plans generated with standard helical free-breathing CT (FBCT) with plans generated on 4D-CT contoured volumes to determine whether target volume coverage is affected. Materials and methods: Fifteen patients with stage I to IV NSCLC were enrolled in the study. Free-breathing CT and 4D-CT data sets were acquired at the same simulation session and with the same immobilization. Gross tumor volume (GTV) for primary and/or nodal disease was contoured on FBCT (GTV_3D). The 3DCRT plans were obtained, and the patients were treated according to our institution’s standard protocol using FBCT imaging. Gross tumor volume was contoured on 4D-CT for primary and/or nodal disease on all 10 respiratory phases and merged to create internal gross tumor volume (IGTV)_4D. Clinical target volume margin was 5 mm in both plans, whereas planning tumor volume (PTV) expansion was 1 cm axially and 1.5 cm superior/inferior for FBCT-based plans to incorporate setup errors and an estimate of respiratory-mediated tumor motion vs 8 mm isotropic margin for setup error only in all 4D-CT plans. The 3DCRT plans generated from the FBCT scan were copied on the 4D-CT data set with the same beam parameters. GTV_3D, IGTV_4D, PTV, and dose volume histogram from both data sets were analyzed and compared. Dice coefficient evaluated PTV similarity between FBCT and 4D-CT data sets. Results: In total, 14 of the 15 patients were analyzed. One patient was excluded as there was no measurable GTV. Mean GTV_3D was 115.3 cm3 and mean IGTV_4D was 152.5 cm3 ( P = .001). Mean PTV_3D was 530.0 cm3 and PTV_4D was 499.8 cm3 ( P = .40). Both gross primary and nodal disease analyzed separately were larger on 4D compared with FBCT. D95 (95% isodose line) covered 98% of PTV_3D and 88% of PTV_4D ( P = .003). Mean dice coefficient of PTV_3D and PTV_4D was 84%. Mean lung V20 was 24.0% for the 3D-based plans and 22.7% for the 4D-based plans ( P = .057). Mean heart V40 was 12.1% for the 3D-based plans and 12.7% for the 4D-based plans ( P = .53). Mean spinal cord Dmax was 2517 and 2435 cGy for 3D-based and 4D-based plans, respectively ( P = .019). Mean esophageal dose was 1580 and 1435 cGy for 3D and 4D plans, respectively ( P = .13). Conclusions: IGTV_4D was significantly larger than GTV_3D for both primary and nodal disease combined or separately. Mean PTV_3D was larger than PTV_4D, but the difference was not statistically significant. The PTV_4D coverage with 95% isodose line was inferior, indicating the importance of incorporating the true size and shape of the target volume. Relatively less dose was delivered to spinal cord and esophagus with plans based on 4D data set. Dice coefficient analysis for degree of similarity revealed that 16% of PTVs from both data sets did not overlap, indicating different anatomical positions of the PTV due to tumor/nodal motion during a respiratory cycle. All patients with lung cancer planned for radical radiotherapy should have 4D-CT simulation to ensure accurate coverage of the target volumes.
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Ammer, Regina, Ulrich Rüde, Matthias Markl, Vera Jüchter e Carolin Körner. "Validation experiments for LBM simulations of electron beam melting". International Journal of Modern Physics C 25, n. 12 (dicembre 2014): 1441009. http://dx.doi.org/10.1142/s0129183114410095.
Abstract (sommario):
This paper validates three-dimensional (3D) simulation results of electron beam melting (EBM) processes by comparing experimental and numerical data. The physical setup is presented which is discretized by a 3D thermal lattice Boltzmann method (LBM). An experimental process window is used for the validation depending on the line energy injected into the metal powder bed and the scan velocity of the electron beam. In the process window, the EBM products are classified into the categories, porous, good and swelling, depending on the quality of the surface. The same parameter sets are used to generate a numerical process window. A comparison of numerical and experimental process windows shows a good agreement. This validates the EBM model and justifies simulations for future improvements of the EBM processes. In particular, numerical simulations can be used to explain future process window scenarios and find the best parameter set for a good surface quality and dense products.
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Zhou, Xiang, Hai Wang e Zhong You. "Design of three-dimensional origami structures based on a vertex approach". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 471, n. 2181 (settembre 2015): 20150407. http://dx.doi.org/10.1098/rspa.2015.0407.
Abstract (sommario):
Origami geometric design is fundamental to many engineering applications of origami structures. This paper presents a new method for the design of three-dimensional (3D) origami structures suitable for engineering use. Using input point sets specified, respectively, in the x − z and y − z planes of a Cartesian coordinate system, the proposed method generates the coordinates of the vertices of a folded origami structure, whose fold lines are then defined by straight line segments each connecting two adjacent vertices. It is mathematically guaranteed that the origami structures obtained by this method are developable. Moreover, an algorithm to simulate the unfolding process from designed 3D configurations to planar crease patterns is provided. The validity and versatility of the proposed method are demonstrated through several numerical examples ranging from Miura-Ori to cylinder and curved-crease designs. Furthermore, it is shown that the proposed method can be used to design origami structures to support two given surfaces.
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Finn, Anthony, Stefan Peters, Pankaj Kumar e Jim O’Hehir. "Automated Georectification, Mosaicking and 3D Point Cloud Generation Using UAV-Based Hyperspectral Imagery Observed by Line Scanner Imaging Sensors". Remote Sensing 15, n. 18 (20 settembre 2023): 4624. http://dx.doi.org/10.3390/rs15184624.
Abstract (sommario):
Hyperspectral sensors mounted on unmanned aerial vehicles (UAV) offer the prospect of high-resolution multi-temporal spectral analysis for a range of remote-sensing applications. However, although accurate onboard navigation sensors track the moment-to-moment pose of the UAV in flight, geometric distortions are introduced into the scanned data sets. Consequently, considerable time-consuming (user/manual) post-processing rectification effort is generally required to retrieve geometrically accurate mosaics of the hyperspectral data cubes. Moreover, due to the line-scan nature of many hyperspectral sensors and their intrinsic inability to exploit structure from motion (SfM), only 2D mosaics are generally created. To address this, we propose a fast, automated and computationally robust georectification and mosaicking technique that generates 3D hyperspectral point clouds. The technique first morphologically and geometrically examines (and, if possible, repairs) poorly constructed individual hyperspectral cubes before aligning these cubes into swaths. The luminance of each individual cube is estimated and normalised, prior to being integrated into a swath of images. The hyperspectral swaths are co-registered to a targeted element of a luminance-normalised orthomosaic obtained using a standard red–green–blue (RGB) camera and SfM. To avoid computationally intensive image processing operations such as 2D convolutions, key elements of the orthomosaic are identified using pixel masks, pixel index manipulation and nearest neighbour searches. Maximally stable extremal regions (MSER) and speeded-up robust feature (SURF) extraction are then combined with maximum likelihood sample consensus (MLESAC) feature matching to generate the best geometric transformation model for each swath. This geometrically transforms and merges individual pushbroom scanlines into a single spatially continuous hyperspectral mosaic; and this georectified 2D hyperspectral mosaic is then converted into a 3D hyperspectral point cloud by aligning the hyperspectral mosaic with the RGB point cloud used to create the orthomosaic obtained using SfM. A high spatial accuracy is demonstrated. Hyperspectral mosaics with a 5 cm spatial resolution were mosaicked with root mean square positional accuracies of 0.42 m. The technique was tested on five scenes comprising two types of landscape. The entire process, which is coded in MATLAB, takes around twenty minutes to process data sets covering around 30 Ha at a 5 cm resolution on a laptop with 32 GB RAM and an Intel® Core i7-8850H CPU running at 2.60 GHz.
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Yan, Jiang, Li Qiang, Wang Guanyao, Wang Ben e Deng Wei. "Monitoring Method of Transmission Line Breaking Prevention Based on Deep Learning". E3S Web of Conferences 252 (2021): 01024. http://dx.doi.org/10.1051/e3sconf/202125201024.
Abstract (sommario):
With the rapid development of the national economy, the national power consumption level continues to increase, which puts forward higher requirements on the power supply guarantee capacity of the power grid system. The distribution range of the transmission line is wide and densely, most lines are exposed to the unguarded field without any shielding or protective measures, which are vulnerable to man-made destruction or natural disasters. Therefore, it is very important for the early monitoring and prevention of the external force breaking of the transmission lines. The method for preventing external breakage of transmission lines based on deep learning proposed in this paper utilizes the video data collected by the cameras erected on the transmission line roads to perform feature extraction and learning through 3D CNN and LSTM networks, and obtains a monitoring model for external breakage prevention of transmission lines. The model was tested on public data sets and verified that it has a good performance in the field of transmission lines against external damage. The method in this paper makes full use of the existing video acquisition equipment, and the process does not require human intervention, which greatly reduces the cost of line monitoring and the hidden dangers of accidents.
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Huang, Zhaoguo, Junlan Chen, Xiucheng Guo e Changxi Ma. "Optimization Method of Transfer Streamlines in Integrated Passenger Hubs Based on 3D Spatial Perspective". Sustainability 15, n. 10 (19 maggio 2023): 8296. http://dx.doi.org/10.3390/su15108296.
Abstract (sommario):
To optimize the functional space layout of various transportation modes of the integrated passenger transport hub, and improve the transfer efficiency and service quality of the hub, a quantitative analysis of the transfer flow lines of the integrated passenger hub is carried out. The research clarifies the layout factors of the functional areas of the “get on and drop off areas” for each mode of transportation, generates a candidate set of the placement of each functional area, and determines the priority ranking of the candidate sets and the transfer starting and end locations. Based on the analysis of passenger route selection factors, the basic transfer streamline network is generated. The basic network is distributed according to the improved shortest path allocation algorithm, and the relevant parameters are calculated to simplify the initial transfer streamline network, generate and compare the initial network plan of the transfer streamline. Take Wuxi Integrated Passenger Transport Hub as an example to verify: when the weight coefficient λ = 0.65 and the number of allocations n = 207, the optimal solution T = 2,738,027 s is obtained. As the calculation is based on the 15,000 passenger transfer flow at Wuxi Station, the optimized average transfer time per person is 3 min 2 s. Compared with the current average transfer time per person at Wuxi Station of 4.5 min, the optimization effect of this paper is significant. The initial network generation and comparison method of the transfer flow line enables the space layout of the transportation modes of the hub to be coordinated with the transfer flow line design, and solves the problem of the transfer flow line design when the hub building space layout is determined. The hub is designed to meet the requirements of functional space layout, passenger transfer needs and interchange efficiency at the initial stage of architectural design.
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Wu, Jin Liang, e Ji He. "Determination of Volumetric Joint Count Based on 3D Fracture Network and its Application in Engineering". Applied Mechanics and Materials 580-583 (luglio 2014): 907–11. http://dx.doi.org/10.4028/www.scientific.net/amm.580-583.907.
Abstract (sommario):
Volumetric joint countis an important parameter to evaluate the development of fractures. It is a fundamental representative for the strength and permeability of rock masses. However, cannot be directly measured in field. In this study, an indirect method is applied for its estimation. The main procedures are as follows: firstly, the volumetric joint frequencyis assumed for th fracture set, and then a series of 3D stochastic discrete fracture networks (DFNs) are generated using the Monte Carlo method according to; secondly, a survey line is drawn perpendicular to the fracture set in the each fracture network generated, the fracture spacing is measured along the survey line, then the average fracture spacing and its variance coefficient are calculated from all the DFNs; thirdly, by repeating the above two steps for differentassumed, the relevant average fracture spacing and its variance coefficient are obtained, and two relation curves are built up between and the average fracture spacing (or its variance coefficient); fourth, the exactis estimated through this relation curve between and the average fracture spacing according to the exact fracture spacing measured in situ; finally,is calculated by summing the exactof all fracture sets up. In this study, this indirect method is applied in the rock masses of Xiaowan Hydropower Station. The result shows that the fracture spacing will reduce and its variation coefficient becomes stable asincreases.
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Jolly, Jean-Baptiste, Kirsten K. Knudsen e Flora Stanley. "linestacker: a spectral line stacking tool for interferometric data". Monthly Notices of the Royal Astronomical Society 499, n. 3 (25 settembre 2020): 3992–4010. http://dx.doi.org/10.1093/mnras/staa2908.
Abstract (sommario):
ABSTRACT linestacker is a new open access and open source tool for stacking of spectral lines in interferometric data. linestacker is an ensemble of casa tasks, and can stack both 3D cubes or already extracted spectra. The algorithm is tested on increasingly complex simulated data sets, mimicking Atacama Large Millimeter/submillimeter Array, and Karl G. Jansky Very Large Array observations of [C ii] and CO(3–2) emission lines, from z ∼ 7 and z ∼ 4 galaxies, respectively. We find that the algorithm is very robust, successfully retrieving the input parameters of the stacked lines in all cases with an accuracy ≳90 per cent. However, we distinguish some specific situations showcasing the intrinsic limitations of the method. Mainly that high uncertainties on the redshifts (Δz > 0.01) can lead to poor signal-to-noise ratio improvement, due to lines being stacked on shifted central frequencies. Additionally, we give an extensive description of the embedded statistical tools included in linestacker: mainly bootstrapping, rebinning, and subsampling. Velocity rebinning is applied on the data before stacking and proves necessary when studying line profiles, in order to avoid artificial spectral features in the stack. Subsampling is useful to sort the stacked sources, allowing to find a subsample maximizing the searched parameters, while bootstrapping allows to detect inhomogeneities in the stacked sample. linestacker is a useful tool for extracting the most from spectral observations of various types.
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Ruiu, Jeremy, Guillaume Caumon e Sophie Viseur. "Semiautomatic interpretation of 3D sedimentological structures on geologic images: An object-based approach". Interpretation 3, n. 3 (1 agosto 2015): SX63—SX74. http://dx.doi.org/10.1190/int-2015-0004.1.
Abstract (sommario):
The characterization of sedimentary structures is an important step in constructing quantitative models of sedimentary deposits from digital images, such as 3D seismic data, satellite images, or digital outcrops. However, the interpretation of these structures generally consists of tedious line pickings followed by surface modeling to define geobodies. Automatic geobody extraction is an alternative, but it is sensitive to image noise, and it does not account for prior sedimentary knowledge. We decided to combine minimal picking by an interpreter with object-guided image processing and optimization to achieve fast and semiautomatic geobody interpretation. Our approach used a realistic volumetric geobody representation based on nonuniform rational basis splines, which can easily be deformed by the interpreter and numerical optimization. Custom edge detection guided by some initial rough interpretations was performed to strengthen the most relevant edges in the picture. Automatic optimization was then computed to fit the initial geobody to these highlighted edges. This approach was applied on satellite pictures showing alluvial channels, and some preliminary results on 3D seismic time slices were also presented. The interpreted channels were then used in a retrodeformation process to automatically reconstruct the point bars. This semiautomatic method opens new perspectives to help interpreters rapidly come up with 3D models of sedimentary structures from subsurface and analog surface data sets.
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Incrapera, Angela K., Chung How Kau, Jeryl D. English, Kathleen McGrory e David M. Sarver. "Soft Tissue Images from Cephalograms Compared With Those from a 3D Surface Acquisition System". Angle Orthodontist 80, n. 1 (1 gennaio 2010): 58–64. http://dx.doi.org/10.2319/111408-583.1.
Abstract (sommario):
Abstract Objective: To assess whether 2D cephalometrics is comparable with 3D imaging devices and whether 3D technology could replace traditional 2D image capture in posttreatment evaluation. Materials and Methods: The study is a prospective evaluation of superimposition techniques obtained from a cohort of 40 patients who underwent orthognathic surgery in a private practice environment. Surgical records were obtained from lateral cephalometric radiographs taken by a Kodak 8000C machine, and the 3D images were obtained from the 3dMD stereo photogrammetric camera capture system. Pre- and postlateral cephalometric records were superimposed on the cranial base (SN line) while pre- and post-3D surgical records were superimposed on the regional best-fit method. A mathematical algorithm, or best-fit calculation, was carried out on the selected surfaces. Each set of superimposed records was analyzed, and five soft tissue landmarks were plotted. The differences between the five surface points were analyzed for each set of records. Results: The final sample consisted of 34 subjects with full records. A total of 680 surface landmarks were plotted and analyzed. The mean differences of the soft tissue landmarks were analyzed for each pair of data sets and were found to range between 1.06 and 8.07 mm and 1.26 and 7.34 mm for lateral cephalometric and 3D readings, respectively. Paired t-tests were carried out using the SPSS 15.0 software, and they showed that the results were not statistically significant between the superimposition techniques on the image capture systems (P > .05). Conclusions: The types of superimposition techniques used in the imaging modalities studied were comparable with one another.
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Abdullah, S. M., M. Awrangjeb e G. Lu. "LiDAR Segmentation using Suitable Seed Points for 3D Building Extraction". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-3 (11 agosto 2014): 1–8. http://dx.doi.org/10.5194/isprsarchives-xl-3-1-2014.
Abstract (sommario):
Effective building detection and roof reconstruction has an influential demand over the remote sensing research community. In this paper, we present a new automatic LiDAR point cloud segmentation method using suitable seed points for building detection and roof plane extraction. Firstly, the LiDAR point cloud is separated into "ground" and "non-ground" points based on the analysis of DEM with a height threshold. Each of the non-ground point is marked as coplanar or non-coplanar based on a coplanarity analysis. Commencing from the maximum LiDAR point height towards the minimum, all the LiDAR points on each height level are extracted and separated into several groups based on 2D distance. From each group, lines are extracted and a coplanar point which is the nearest to the midpoint of each line is considered as a seed point. This seed point and its neighbouring points are utilised to generate the plane equation. The plane is grown in a region growing fashion until no new points can be added. A robust rule-based tree removal method is applied subsequently to remove planar segments on trees. Four different rules are applied in this method. Finally, the boundary of each object is extracted from the segmented LiDAR point cloud. The method is evaluated with six different data sets consisting hilly and densely vegetated areas. The experimental results indicate that the proposed method offers a high building detection and roof plane extraction rates while compared to a recently proposed method.
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Purusothaman, Abimanyu, Abderrahmane Baïri e Nagarajan Nithyadevi. "3D natural convection on a horizontal and vertical thermally active plate in a closed cubical cavity". International Journal of Numerical Methods for Heat & Fluid Flow 26, n. 8 (7 novembre 2016): 2528–42. http://dx.doi.org/10.1108/hff-08-2015-0341.
Abstract (sommario):
Purpose The purpose of this paper is to examine numerically the natural convection heat transfer in a cubical cavity induced by a thermally active plate. Effects of the plate size and its orientation with respect to the gravity vector on the convective heat transfer and the flow structures inside the cavity are studied and highlighted. Design/methodology/approach The numerical code is based on the finite volume method with semi-implicit method for pressure-linked equation algorithm. The convective and diffusive terms in momentum equations are handled by adopting the power law scheme. Finally, the discretized sets of algebraic equations are solved by the line-by-line tri-diagonal matrix algorithm. Findings The results show that plate orientation and size plays a significant role on heat transfer. Also, the heat transfer rate is an increasing function of Rayleigh number for both orientations of the heated plate. Depending on the thermal management of the plate and its application (as in electronics), the heat transfer rate is maximized or minimized by selecting appropriate parameters. Research limitations/implications The flow is assumed to be 3D, time-dependent, laminar and incompressible with negligible viscous dissipation and radiation. The fluid properties are assumed to be constant, except for the density in the buoyancy term that follows the Boussinesq approximation. Originality/value The present work will give some additional knowledge in designing sealed cavities encountered in some engineering applications as in aeronautics, automobile, metallurgy or electronics.
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Yan, Rui-Jun, Jing Wu, Ji Yeong Lee e Chang-Soo Han. "Representation of 3D Environment Map Using B-Spline Surface with Two Mutually Perpendicular LRFs". Mathematical Problems in Engineering 2015 (2015): 1–14. http://dx.doi.org/10.1155/2015/690310.
Abstract (sommario):
This paper proposes a map representation method of three-dimensional (3D) environment by using B-spline surfaces, which are first used to describe large environment in 3D map construction research. Initially, a 3D point cloud map is constructed based on extracted line segments with two mutually perpendicular 2D laser range finders (LRFs). Then two types of accumulated data sets are separated from the point cloud map according to different types of robot movements, continuous translation and continuous rotation. To express the environment more accurately, B-spline surface with covariance matrix is proposed to be extracted from each data set. Due to the random movements, there must be overlap between extracted B-spline surfaces. However, merging of two overlapping B-spline surfaces with different distribution directions of their control points is a complex problem, which is not well addressed by far. In our proposed method, each surface is divided into overlap and nonoverlap. Then generated sample points with propagated uncertainties from one overlap and their projection points located on the other overlap are merged using the product of Gaussian probability density functions. Based on this merged data set, a new surface is extracted to represent the environment instead of the two overlaps. Finally, proposed methods are validated by using the experimental result of an accurate representation of an indoor environment with B-spline surfaces.
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Bétaille, David, François Peyret e Maxime Voyer. "Applying Standard Digital Map Data in Map-aided, Lane-level GNSS Location". Journal of Navigation 68, n. 5 (31 marzo 2015): 827–47. http://dx.doi.org/10.1017/s0373463315000132.
Abstract (sommario):
Urban positioning using the Global Positioning System (GPS) is challenging because of multipath. Urban canyons limit open sky visibility, and cause signal reflection and diffraction, resulting in significant satellite range measurement errors. The investigations reported here have been carried out in a French project calledInturb(an acronym derived from integrity and urban positioning). So far, the project has had two phases: first, a simple Three-Dimensional (3D) geometrical city modelling, called “Urban Trench”, has been developed and engineered manually from data sets collected in different cities. Positioning improvement in terms of accuracy was quantified where the model could be applied. Second, this modelling has been automated, based on the standard national BD Topo ® map database for France, with promising results. This geometrical modelling makes it possible to distinguish between line-of-sight satellite signals and those from non-line-of-sight. The latter, apparentlybona fide, signals are caused by strong reflections, usually from buildings with a lot of steel and glass in their construction. A correction of the pseudo-range measurements of the latter is also computed and applied in the position estimator. Positioning accuracy is improved, whilst availability is kept at its maximum. In the study both manual and automatic 3D models are used in extensive experimental campaigns. Results are: first, the possibility to cover entirely any urban area in the country; second, the reduction of the median error in 3D by more than 50% on data collected in Nantes, Paris and Toulouse for a total duration of nearly ten hours; third, the compliance with standards used in most embedded maps and geographical information systems, including an assessment of the trade-off between the model simplicity and the positioning improvement.
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Haase, I., P. Gläser e J. Oberst. "BUNDLE ADJUSTMENT OF SPACEBORNE DOUBLE-CAMERA PUSH-BROOM IMAGERS AND ITS APPLICATION TO LROC NAC IMAGERY". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W13 (5 giugno 2019): 1397–404. http://dx.doi.org/10.5194/isprs-archives-xlii-2-w13-1397-2019.
Abstract (sommario):
<p><strong>Abstract.</strong> The TU Berlin group of the Lunar Reconnaissance Orbiter Camera (LROC) team has implemented a Bundle Adjustment (BA) for spaceborne multi-lenses line scan imagers, by rigorously modeling the geometric properties of the image acquisition. The BA was applied to stereo image sets of the LROC Narrow Angle Camera (NAC) and first results show, that the overall geometry of the stereo models were significantly improved. Ray intersection accuracies of initially up to several meters were homogenized within the integrated stereo models and improved to 0.14&thinsp;m on average. The mean point error of the adjusted 3D object points was estimated by the BA to be 0.95&thinsp;m. The inclusion of available Lunar Orbiter Laser Altimeter (LOLA) shots as 3D ground control to the BA, accurately tied to the image space by an aforegoing co-registration, allowed to register the final adjusted NAC DTM to the currently most accurate global lunar reference frame. The BA also provides accuracy assessments of the individual LOLA tracks used for georeference during the adjustment, which will be useful to further assess LOLA derived products.</p>
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Parpala, Radu Constantin, Diana Popescu e Cristina Pupaza. "Infill parameters influence over the natural frequencies of ABS specimens obtained by extrusion-based 3D printing". Rapid Prototyping Journal 27, n. 6 (1 luglio 2021): 1273–85. http://dx.doi.org/10.1108/rpj-05-2020-0110.
Abstract (sommario):
Purpose The mechanical performances of 3D-printed parts are influenced by the manufacturing variables. Many studies experimentally evaluate the impact of the process parameters on specimens’ static and dynamic behavior with the aim of tailoring the mechanical response of the prints. However, this experimental approach is hampered by the very large number of parameters, 3D printers and materials, the development of computer simulation models being thus required. In the context, this study aims to fill a gap by experimentally investigating the influence of infill related parameters over the vibrations of 3D-printed specimens, as well as to propose and validate a parametric finite element (FE) model for the prediction of eigenfrequencies. Design/methodology/approach A generally applicable FE model is not yet available for the 3D printing technology based on the material extrusion process due to the large number of parameters settings that determine a large variability of outcomes. Hence, the idea of developing numerical simulation models that address sets of parameters and assess their impact on a certain mechanical property. For the natural frequency, the influence of the infill density and infill line width is studied in this paper. An FE script that automates the generation of the model geometry by using the considered set of parameters is developed and run. The results of the modal analysis are compared to the experimental values for validating the script. Findings Based on the experimental results, a linear regression between the weight of the part and the first natural frequency is established. The response surfaces indicate that the infill density is the most significant parameter of influence. The weight-frequency function is then used for the prediction of the natural frequency of specimens manufactured with other infill parameters and values, including different infill patterns. Practical implications As the malfunctions or mechanical damages can be caused by the resonant vibration of parts during use, this research develops a FE-parameterized model that evaluates and predicts the eigenfrequencies of 2D printed parts to prevent these undesirable events. The targeted functional applications are those in which 3D-printed polymer parts are used, such as drone arms or drone propellers. Originality/value This research studies the influence of process parameters on the natural frequency of 3D-printed polylactic acid specimens, a topic scarcely addressed in literature. It also proposes a new approach for the development of parameterized FE models for sets of parameters, instead of a general model, to reduce the time and resources allocated to the experimental tests. Such a model is provided in this paper for evaluating the influence of infill parameters on 3D prints eigenfrequency. The numerical model is validated for other infill settings.
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Pu, S., L. Xie, M. Ji, Y. Zhao, W. Liu, L. Wang, Y. Zhao, F. Yang e D. Qiu. "REAL-TIME POWERLINE CORRIDOR INSPECTION BY EDGE COMPUTING OF UAV LIDAR DATA". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W13 (4 giugno 2019): 547–51. http://dx.doi.org/10.5194/isprs-archives-xlii-2-w13-547-2019.
Abstract (sommario):
<p><strong>Abstract.</strong> This paper presents an innovative power line corridor inspection approach using UAV LiDAR edge computing and 4G real real-time transmission. First, sample point clouds of power towers are manually classified and decomposed into components according to five mainstream tower types: T type, V type, n type, I type and owl head type. A deep learning AI agent, named “Tovos Age Agent” internally, is trained by supervised deep learning the sample data sets under a 3D CNN framework. Second, laser points of power line corridors are simultaneously classified into Ground, Vegetation, Tower, Cable, and Building types using semantic feature constraints during the UAV-borne LiDAR acquisition process, and then tower types are further recognized by Tovos Agent for strain span separation. Spatial and topological relations between Cable points and other types are analyzed according to industry standards to identify potential risks at the same time. Finally, all potential risks are organized as industry standard reports and transmitted onto central server via 4G data link, so that maintenance personal can be notified the risks as soon as possible. Tests on LiDAR data of 1000&thinsp;KV power line show the promising results of the proposed method.</p>
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Zhang, Zhuang, Rujin Zhao, Enhai Liu, Kun Yan e Yuebo Ma. "A Convenient Calibration Method for LRF-Camera Combination Systems Based on a Checkerboard". Sensors 19, n. 6 (15 marzo 2019): 1315. http://dx.doi.org/10.3390/s19061315.
Abstract (sommario):
In this paper, a simple and easy high-precision calibration method is proposed for the LRF-camera combined measurement system which is widely used at present. This method can be applied not only to mainstream 2D and 3D LRF-cameras, but also to calibrate newly developed 1D LRF-camera combined systems. It only needs a calibration board to record at least three sets of data. First, the camera parameters and distortion coefficients are decoupled by the distortion center. Then, the spatial coordinates of laser spots are solved using line and plane constraints, and the estimation of LRF-camera extrinsic parameters is realized. In addition, we establish a cost function for optimizing the system. Finally, the calibration accuracy and characteristics of the method are analyzed through simulation experiments, and the validity of the method is verified through the calibration of a real system.
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Gómez, Julián L., Danilo R. Velis e Juan I. Sabbione. "Noise suppression in 2D and 3D seismic data with data-driven sifting algorithms". GEOPHYSICS 85, n. 1 (11 novembre 2019): V1—V10. http://dx.doi.org/10.1190/geo2019-0099.1.
Abstract (sommario):
We have developed an empirical-mode decomposition (EMD) algorithm for effective suppression of random and coherent noise in 2D and 3D seismic amplitude data. Unlike other EMD-based methods for seismic data processing, our approach does not involve the time direction in the computation of the signal envelopes needed for the iterative sifting process. Instead, we apply the sifting algorithm spatially in the inline-crossline plane. At each time slice, we calculate the upper and lower signal envelopes by means of a filter whose length is adapted dynamically at each sifting iteration according to the spatial distribution of the extrema. The denoising of a 3D volume is achieved by removing the most oscillating modes of each time slice from the noisy data. We determine the performance of the algorithm by using three public-domain poststack field data sets: one 2D line of the well-known Alaska 2D data set, available from the US Geological Survey; a subset of the Penobscot 3D volume acquired offshore by the Nova Scotia Department of Energy, Canada; and a subset of the Stratton 3D land data from South Texas, available from the Bureau of Economic Geology at the University of Texas at Austin. The results indicate that random and coherent noise, such as footprint signatures, can be mitigated satisfactorily, enhancing the reflectors with negligible signal leakage in most cases. Our method, called empirical-mode filtering (EMF), yields improved results compared to other 2D and 3D techniques, such as [Formula: see text] EMD filter, [Formula: see text] deconvolution, and [Formula: see text]-[Formula: see text]-[Formula: see text] adaptive prediction filtering. EMF exploits the flexibility of EMD on seismic data and is presented as an efficient and easy-to-apply alternative for denoising seismic data with mild to moderate structural complexity.
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Scholz, Felicitas, Mustafa Cevik, Philipp Hallensleben, Pascal Thome, Gunther Eggeler e Jan Frenzel. "A 3D Analysis of Dendritic Solidification and Mosaicity in Ni-Based Single Crystal Superalloys". Materials 14, n. 17 (28 agosto 2021): 4904. http://dx.doi.org/10.3390/ma14174904.
Abstract (sommario):
Ni-based single crystal superalloys contain microstructural regions that are separated by low-angle grain boundaries. This gives rise to the phenomenon of mosaicity. In the literature, this type of defect has been associated with the deformation of dendrites during Bridgman solidification. The present study introduces a novel serial sectioning method that allows to rationalize mosaicity on the basis of spatial dendrite growth. Optical wide-field micrographs were taken from a series of cross sections and evaluated using quantitative image analysis. This allowed to explore the growth directions of close to 2500 dendrites in a large specimen volume of approximately 450 mm3. The application of tomography in combination with the rotation vector base-line electron back-scatter diffraction method allowed to analyze how small angular differences evolve in the early stages of solidification. It was found that the microstructure consists of dendrites with individual growth directions that deviate up to ≈4° from the average growth direction of all dendrites. Generally, individual dendrite growth directions coincide with crystallographic <001> directions. The quantitative evaluation of the rich data sets obtained with the present method aims at contributing to a better understanding of elementary processes that govern competitive dendrite growth and crystal mosaicity.
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Peng, Qingming, Zhongzheng Wang, Gongwen Wang, Wengao Zhang, Zhengle Chen e Xiaoning Liu. "3D Mineral Prospectivity Mapping from 3D Geological Models Using Return–Risk Analysis and Machine Learning on Imbalance Data". Minerals 13, n. 11 (29 ottobre 2023): 1384. http://dx.doi.org/10.3390/min13111384.
Abstract (sommario):
Three-dimensional Mineral Prospectivity Mapping (3DMPM) is an innovative approach to mineral exploration that combines multiple geological data sources to create a three-dimensional (3D) model of a mineral deposit. It provides an accurate representation of the subsurface that can be used to identify areas with mineral potential. These 3D geological models are the typical data source for 3D prospective modeling. Geological data sets from multiple sources are used to construct 3D geological models. Since in practice there is a significant imbalance in the ratio of mineralized to non-mineralized classes, the classification results will be biased in favor of the more observed classes. Borderline-SMOTE (BLSMOTE) is an oversampling technique used to solve the problem of unbalanced datasets and works by generating synthetic data points along the boundary line between the minority and majority classes. This helps to create a more balanced dataset without introducing too much noise. Non-mineralized samples can be generated by randomly selecting non-mineralized locations, which means that uncertainties are generated. In this paper, we take the shallow-forming low-temperature hydrothermal deposit Guizhou Lannigou gold deposit as an example to extract the ore-controlling elements and establish a 3D geological model. A total of 50 training samples are generated using the sampling method described above, and 50 mineralization prospects are generated using Random Forests. A return–risk analysis was used to explore the uncertainties associated with synthetic positive samples and randomly selected negative samples, and to determine the final mineral potential values. Based on the evaluation metrics G-mean and F-value, the model using BLSMOTE outperforms the model without the synthetic algorithm and the models using SMOTE and KMeansSMOTE. The optimal model BLSMOTE18 has an AUC of 0.9288. The methodology also performs superiorly with different levels of class imbalance datasets. Excluding the predictions where the results highly overlap with known deposits, five target zones were circled for the targets using a P-A plot, all of which have obvious metallogenic geological features. Among them, Target1 and Target2 have good potential for mineralization, which is of great significance for future mineral exploration work.