Three-dimensional Laser Scanning Technology Research Articles

Full-Section Deformation Monitoring of High-Altitude Fault Tunnels Based on Three-Dimensional Laser Scanning Technology.

In traditional tunnel monitoring, the characteristic points of an object within a tunnel are measured to obtain information about the object. Considering the limitations of the traditional method in measuring the complex surface structure of tunnels, such as limited monitoring points, a long measurement period, and low precision, this study introduces an approach that uses three-dimensional (3D) laser scanning for monitoring tunnel cross-section deformation. Using this approach, the soft surrounding rock of a high-altitude ultralong tunnel was taken as the monitoring object. The test tunnel was first scanned using a 3D laser scanner, and the collected data were processed. The internal structural data of the tunnel were subsequently compared with its actual contour lines and the data of its primary branch and secondary lining on different dates. The results indicate that the arch roof of the tunnel tended to be stable within a certain time range when the positions of the primary branch and secondary lining were at different measuring points with different pile numbers. The deformation of the pile number on the left and right sides did not generally exceed 0.02 m, except at a few measuring points. A comparison between the actual cross section of the initial branch and that of the designed section showed that the actual elevation of the arch of the initial branch of the tunnel was greater than its designed elevation by no more than 0.3 m. Hence, through this study, a convenient and practical method is presented for monitoring deformation in complex curved tunnel structures.

Modelling and protection of grotto temples based on iterative closest point and Poisson

As a non-renewable cultural heritage, grotto temples face many value threats and the crises of rapid extinction. Due to the unique environment, diverse volume and complex geometric structure of grotto temples, cultural relic protection faces huge challenges. Digitisation has become the most important and effective preventive protection method. This study proposes a comprehensive modeling method, which uses three-dimensional (3D) laser scanning technology to obtain the point cloud data of grotto ruins, close range photogrammetry to obtain multi-angle and high-resolution two-dimensional (2D) image data, and through the fusion modelling of the laser point cloud and image dense matching point cloud, a complete geometric model of grotto is obtained. The registration method of the improved algorithm is based on Euclidean distance residual. The performance is better, with residuals mainly distributed in the range of 0.02 to 0.03 mm. In terms of texture mapping, the accuracy of model mapping is adjusted by adjusting the constraints of control points. The gray values of 50 pixels around the control points show significant gradient changes in the X direction, while the changes in the Y direction are relatively small. These methods and technologies provide practical and effective means for the protection and preservation of cultural relics in grotto temples.

A Coal Mine Tunnel Deformation Detection Method Using Point Cloud Data.

In recent years, the deformation detection technology for underground tunnels has played a crucial role in coal mine safety management. Currently, traditional methods such as the cross method and those employing the roof abscission layer monitoring instrument are primarily used for tunnel deformation detection in coal mines. With the advancement of photogrammetric methods, three-dimensional laser scanners have gradually become the primary method for deformation detection of coal mine tunnels. However, due to the high-risk confined spaces and distant distribution of coal mine tunnels, stationary three-dimensional laser scanning technology requires a significant amount of labor and time, posing certain operational risks. Currently, mobile laser scanning has become a popular method for coal mine tunnel deformation detection. This paper proposes a method for detecting point cloud deformation of underground coal mine tunnels based on a handheld three-dimensional laser scanner. This method utilizes SLAM laser radar to obtain complete point cloud information of the entire tunnel, while projecting the three-dimensional point cloud onto different planes to obtain the coordinates of the tunnel centerline. By using the calculated tunnel centerline, the three-dimensional point cloud data collected at different times are matched to the same coordinate system, and then the tunnel deformation parameters are analyzed separately from the global and cross-sectional perspectives. Through on-site collection of tunnel data, this paper verifies the feasibility of the algorithm and compares it with other centerline fitting and point cloud registration algorithms, demonstrating higher accuracy and meeting practical needs.

Transmission line tower inclination measurement method based on three-dimensional laser scanning and inter frame difference

Abstract The purpose of this study is to propose a method based on three-dimensional laser scanning and frame difference technology to measure the inclination of transmission line towers, so as to realize accurate monitoring of transmission line structure. Firstly, the multi-scale Retinex algorithm is used to enhance and preprocess the transmission line tower image to improve the image quality. Secondly, the method of frame difference and background difference is combined to detect and identify the inclined tower. Finally, the point cloud data of inclined tower is obtained by using three-dimensional laser scanning technology, and the inclination of transmission line tower is calculated by coordinates. The experimental results show that this method has high accuracy and reliability, with an error of less than 0.15 × 10−5 and an inclination of less than 0.17°. It is proved that this method can improve the monitoring efficiency of transmission lines, has good effects in engineering practice, and can provide effective means for the safe operation of transmission line structures.

Corrosion characteristics and evaluation of galvanized high-strength steel wire for bridge cables based on 3D laser scanning and image recognition

The study investigates the corrosion behavior of galvanized high-strength steel wire, which significantly affects the bearing capacity and residual fatigue life of cables in cable-supported bridges. Through standardized salt spray accelerated corrosion tests, steel wires with varying corrosion degrees are obtained. Three-dimensional laser scanning technology reconstructs the corroded wire surface, while image recognition techniques extract geometric characteristics of corrosion pits. Fitting expressions are established to correlate the minimum cross-sectional area, maximum pit depth and dip angle, and mass loss ratio of the wire. Statistical analysis reveals log-normal distributions for the lengths of major and minor axes of corrosion pits over time. Fitting curves for elongation after fracture, nominal yield strength, and nominal ultimate strength, along with elastic modulus distribution, are derived for different mass loss ratios. Comparing corrosion grading criteria, the study quantitatively describes corrosion characteristic parameters for distinct corrosion grades. These insights enhance understanding of corrosion behavior and mechanical property degradation in high-strength steel wires, offering a quantitative framework for assessing and classifying corrosion extent based on measurable parameters.

Combined Filtering Method for Offshore Oil and Gas Platform Point Cloud Data Based on KNN_PCF and Hy_WHF and Its Application in 3D Reconstruction.

With the increasing scale of deep-sea oil exploration and drilling platforms, the assessment, maintenance, and optimization of marine structures have become crucial. Traditional detection and manual measurement methods are inadequate for meeting these demands, but three-dimensional laser scanning technology offers a promising solution. However, the complexity of the marine environment, including waves and wind, often leads to problematic point cloud data characterized by noise points and redundancy. To address this challenge, this paper proposes a method that combines K-Nearest-Neighborhood filtering with a hyperbolic function-based weighted hybrid filtering. The experimental results demonstrate the exceptional performance of the algorithm in processing point cloud data from offshore oil and gas platforms. The method improves noise point filtering efficiency by approximately 11% and decreases the total error by 0.6 percentage points compared to existing technologies. Not only does this method accurately process anomalies in high-density areas-it also removes noise while preserving important details. Furthermore, the research method presented in this paper is particularly suited for processing large point cloud data in complex marine environments. It enhances data accuracy and optimizes the three-dimensional reconstruction of offshore oil and gas platforms, providing reliable dimensional information for land-based prefabrication of these platforms.

Characteristics and Applications of Non-destructive Testing Technology in Bridge Engineering

The construction of bridge projects can promote economic exchanges between different regions and provide convenient transportation for people. The application of non-destructive testing technology has effectively improved the overall quality of bridge inspection work, providing a reliable guarantee for the development of the transportation industry. This paper elaborates on the specific principles, characteristics, and research status of ultrasonic testing technology, three-dimensional laser scanning technology, and radiographic testing technology in practical operations, and comprehensively compares the advantages and disadvantages of the three non-destructive testing technologies in bridge engineering. Ultrasonic testing technology has simple operation and low cost, but the detection results are not intuitive enough; three-dimensional laser scanning technology has high accuracy and good digital compatibility, but its cost is relatively high; Radiographic testing technology has a wide range of applications, and the detection results are relatively intuitive, but the detection efficiency is low. Finally, it is discussed that the current difficulties in using non-destructive testing technology in bridge engineering lie in high costs and inadequate integration. It is proposed to incorporate non-destructive testing technology into bridge design planning to form a more complete system.

Reconstruction and Intelligent Evaluation of Three-Dimensional Texture of Stone Matrix Asphalt-13 Pavement for Skid Resistance

To examine the three-dimensional texture structure of SMA-13 asphalt pavement and assess its anti-skid performance, a light gradient-boosting machine evaluation model was developed using non-contact three-dimensional laser-scanning technology. The study focused on collecting three-dimensional texture data from newly laid SMA-13 asphalt pavement. Subsequently, wavelet transform was employed to reconstruct the pavement’s three-dimensional texture, and discrete Fourier transform was utilized to separate macro- and microtextures, enabling the calculation of their characteristics. The macro- and micro-characteristics of the three-dimensional texture and friction coefficient were input into the model. A comparative analysis with linear regression and a random forest model revealed superior accuracy and efficiency in the model. The training set R2 is 0.948, and the testing set R2 is 0.842, effectively enabling the evaluation of pavement anti-skid performance. An analysis of parameter importance indicated that Rku and MPD are still effective indicators for evaluating skid resistance. Furthermore, diverse texture indexes exhibited varying effects on the anti-skid performance. The established asphalt pavement anti-skid evaluation model serves as a theoretical foundation for understanding the actual influence on pavement anti-skid performance.

A Method for Convergent Deformation Analysis of a Shield Tunnel Incorporating B-Spline Fitting and ICP Alignment

The application of three-dimensional laser scanning technology in the field of tunnel deformation monitoring has changed the traditional measurement method. It provides an automated and intelligent solution for monitoring the geometric deformation of tunnel sections due to its high efficiency and independence from environmental influences. In this paper, based on B-spline fitting and iterative nearest point (ICP) alignment, the calculation of the difference between the radial distance and the design radius of a tunnel is transformed into a curve transformation that iterates over the nearest-neighbor points and calculates the difference in the distance between the corresponding points. The innovation of this paper is that the high-precision tunnel deformation monitoring method integrating B-spline fitting and ICP alignment can automatically compensate for the missing point clouds, is not affected by the point clouds of the tunnel inner and outer liner appendages, is more sensitive in the local deformation feedback and can be applied to a variety of tunnel shapes. The results indicate that our method maximally improves the accuracy of the horizontal convergence calculation by 28.6 mm and the accuracy of the vault settlement by 27.8 mm in comparison with the least squares circle fitting algorithm.

Experimental study of fluid-particle flow characteristics in a rough fracture

Rough fractures can significantly affect particle-fluid flow in a stratum, but particle transport characteristics are still not fully understood. This paper proposes a novel method to combine three-dimensional laser scanning and casting technology for making rough transparent panels based on rock fractures. A large model with two-sided rough surfaces is constructed, and the inner sizes are 2 m × 0.3 m × 3 mm. The particle image velocimetry method is used to analyze slurry flow. The experimental results show that distorted irregular streamlines, vortexes, sand settling, and dispersion are primary characteristics of particles transported by low-viscosity fluid. Shear flow can induce prominent vortexes around the inlet and the fracture top. With the increase in fluid viscosity, sand-fluid flow along preferential flow paths, and particle clusters are easily formed due to sand aggregation in tortuous pathways. Increasing the fluid velocity avoids particles plugging around the inlet, and there is a threshold velocity. The vortex number has a negative relationship with fluid viscosity. With the dune accumulation, the vorticity intensity is significantly increased, and discrete vortexes are connected into a large vorticity region, which collapses sand aggregation along the whole fracture. Increasing fluid velocity and viscosity and reducing particle diameter are more effective ways to improve particle distribution than increasing particle concentration. The combination of multiple factors can enhance the more even distribution of particles in rough fractures. The investigation provides a fundamental understanding of slurry flow behaviors in fractured media and is a valuable reference for the simulation of particle-fluid flow.

Effects of Hydraulic Erosion on the Spatial Redistribution Characteristics of Soil Aggregates and SOC on Pisha Sandstone Slope

Under the long-term effects of hydraulic erosion, soil particles and nutrients are continuously lost and enriched in the process of runoff and sediment movement, leading to a change in soil organic carbon (SOC) in different spatial positions on the slope, which is closely related to the carbon balance of the ecosystem. Therefore, the changes in slope erosion intensity and the spatial redistribution characteristics of soil aggregates and SOC under water erosion conditions were quantitatively analyzed by combining field runoff plots with three-dimensional (3D) laser scanning technology. The results showed that: (1) After rainfall, the slope erosion intensity successively declined from the upper to the lower parts of the slope, and the content of soil aggregates in each soil layer changed obviously. The loss of 1–2 mm soil aggregates was the largest in the sedimentary area of the 2–4 cm soil layer, at 0.38 g/kg. The concentration of 0.5–1 mm soil aggregates was the largest in the micro-erosion area of the 2–4 cm soil layer, at 0.36 g/kg. (2) After rainfall, the overall SOC on the slope showed a loss state in the 0–2 cm soil layer and an enrichment state in the 2–4 cm soil layer. Among them, the loss of SOC in the medium erosion area of the 0–1 cm soil layer was the largest, and its content decreased by 57.58%. The enrichment in the 2–4 cm soil layer was the maximum in the micro-eroded area, with a content increase of 79.23%. (3) Before and after rainfall, the SOC of each soil layer was positively correlated with small aggregates, and the correlation gradually tended to be negative with the increase in the particle size of soil aggregates, and the SOC showed a negative correlation with large aggregates (>2 mm).

Generating Topologically Consistent BIM Models of Utility Tunnels from Point Clouds.

The development and utilization of urban underground space is an important way to solve the "great urban disease". As one of the most important types of urban underground foundations, utility tunnels have become increasingly popular in municipal construction. The investigation of utility tunnels is a general task and three-dimensional laser scanning technology has played a significant role in surveying and data acquisition. However, three-dimensional laser scanning technology suffers from noise and occlusion in narrow congested utility tunnel spaces, and the acquired point clouds are imperfect; hence, errors and redundancies are introduced in the extracted geometric elements. The topology of reconstructed BIM objects cannot be ensured. Therefore, in this study, a hierarchical segmentation method for point clouds and a topology reconstruction method for building information model (BIM) objects in utility tunnels are proposed. The point cloud is segmented into facades, planes, and pipelines hierarchically. An improved mean-shift algorithm is proposed to extract wall line features and a local symmetry-based medial axis extraction algorithm is proposed to extract pipelines from point clouds. A topology reconstruction method that searches for the neighbor information of wall and pipeline centerlines and establishes collinear, perpendicular, and intersecting situations is used to reconstruct a topologically consistent 3D model of a utility tunnel. An experiment on the Guangzhou's Nansha District dataset successfully reconstructed 24 BIM wall objects and 12 pipelines within the utility tunnel, verifying the efficiency of the method.

Intelligent Construction Monitoring Method for Large and Complex Steel Structures Based on Laser Point Cloud

Large and complex steel structures play a vital role in building construction. However, deviations between the design model and the actual construction state are inevitable, which seriously affects the quality and safety of building construction. In our study, an intelligent construction monitoring method for large and complex steel structures based on laser point cloud is proposed. Firstly, three-dimensional laser scanning technology is introduced to capture accurate and complete spatial information on steel structures. Then, considering the inconsistency of the coordinate system between the design model and the laser point cloud, the building information model (BIM) is converted into the point cloud model, and the datum unification of the two types of the point cloud is achieved by adopting a coarse-to-fine registration strategy. Finally, the spatial information of steel structures is extracted from the laser point cloud based on the as-designed model, and the distance deviation between the two models is analyzed to reflect the actual construction state. To demonstrate the applicability of the proposed method, the steel structures’ point cloud of the stadium and the high-speed railway station is captured by the terrestrial three-dimensional laser scanner. The experimental results demonstrate that the method can extract the deviation between the design model and the actual construction, to provide accurate data sources for the intelligent fine construction of steel structures.

The Research on Obtaining the Geometric Dimension of Cable-Stayed Bridges Based on 3D Laser Scanning

The traditional manual measurement methods are time-consuming and error-prone when they are used for cable-stayed bridges’ geometric dimensions acquisition. They are always limited by various adverse conditions such as large bridge spans, the high height of bridge towers, more risk of manual operation, and many other unpredictable factors. In contrast, three-dimensional (3D) laser scanning technology is extremely useful for solving the above problems. After obtaining plenty of point cloud data and point cloud models, precise and accurate geometric dimensions of cable-stayed bridges can be obtained accurately and conveniently. Taking a cable-stayed bridge named XingLinBao as an example, the accuracy and convenience of 3D laser scanning are verified.

Evaluation of Concrete Abrasion Using Traditional and High-Speed Underwater Methods

With the increasing height of new dams, the number of high-water-head and high-flow spillway buildings is gradually increasing, and concretes are required to have better abrasion resistance. Current standards offer a method for evaluating the abrasion resistance of concrete, but when evaluating the abrasion resistance of high-performance concretes, it is necessary to extend the test time to more than 120 h. In this study, an improved way of the current code-specified underwater method was proposed to shorten the testing time, called the high-speed underwater method (HSUM), and the test results of the two methods were evaluated using three-dimensional (3D) laser-scanning technology. It was found that the abrasion efficiency of the HSUM was about twice as much as that of the code-specified method. HSUM resulted in a significant acceleration of the concrete coarse aggregate abrasion process. The average abrasion depth of concrete was between 0 and 6.5 mm (HSUM after 15 h and code method after 30 h), and the abrasion mainly occurred on the surface of slurry, when the abrasion resistance of concrete was obviously affected by the strength and volume of slurry. When the average abrasion depth of concrete exceeded 6.5 mm, it entered the aggregate abrasion stage, and its abrasion resistance was influenced by the aggregate hardness and aggregate content, and the correlation with the slurry strength decreases. The surface roughness parameters Sq and Sa of HSUM concrete increase significantly compared with the code method. HSUM allows for a reduction in experimental time and high performance in evaluating the abrasion resistance of high-performance concretes or concretes with special aggregates (high-strength granite aggregates and cast stone aggregates).

A State-of-the-Practice Review of Three-Dimensional Laser Scanning Technology for Tunnel Distress Monitoring

A State-of-the-Practice Review of Three-Dimensional Laser Scanning Technology for Tunnel Distress Monitoring

Theoretical and practical bases of application of three-dimensional laser scanning technology in forensic construction and technical expertise

The article deals with the application of 3D laser scanning technologies in forensic construction and technical expertise, as well as the advantages of using this method. The analysis of the main types of laser scanning is carried out taking into account the size, complexity of the object and its technical features. Examples of effective use of 3D laser scanning in forensic construction and technical expertise are considered.

Analysis of Adhesive Distribution over Particles According to Their Size and Potential Savings from Particle Surface Determination

Wood and its processing into particles are, combined, the largest cost factor in the production of particleboard, followed by the cost of adhesive. Thus, reducing their cost is a goal of process optimization. This study investigated whether possible savings could be identified and quantified by determining the particle surface using automated three-dimensional laser-scanning technology (3D Particleview, Fagus-Grecon). The focus was on saving adhesive by sieving out adhesive-consuming fines. It was shown that, currently, with the actual prices for wood (89 €/t), particle preparation (37 €/t), and adhesive (570 €/t), the resulting additional costs for particles are overcompensated by the savings for adhesive with high adhesive content (e.g., 19%). The assumption of uniform distribution of adhesive on the total surface of all particles was checked for correctness using digital reflected light microscopy (VHX-5000, Keyence). Since urea-formaldehyde (UF) adhesive commonly used in particleboard production can only be detected with increased effort, phenol-formaldehyde (PF) adhesive was applied for the tests. Ultraviolet microspectrophotometry (UMSP) was used to rule out excessive penetration of the adhesive into the wooden tissue of the particles. The examination of the distribution of the adhesive over the surface showed that smaller particle sizes tended to be more heavily coated with adhesive. This means that the calculated savings still underestimate the real-life potential or that potential savings exist even with lower adhesive prices or higher prices for wood.

Three-Dimensional Laser Scanning Technology Assisted Investigation and Extraction of Human Bone Information in Archaeological Sites at Shenna Ruins, China

Three-dimensional laser scanning technology can be used to quickly, efficiently, and accurately obtain spatial three-dimensional information of cultural relics without contacting the target during the scanning process. The results of this study showed that the extraction of human bones from the Shenna ruins via the auxiliary application of three-dimensional scanning technology reduced human intervention and destruction on the site compared with the traditional archaeological human bone packaging and extraction work method. When combined with the application of three-dimensional scanning technology, the original data information extracted on the spot were more comprehensive and accurate. Additionally, the technology provided us with important scientific data which can be used to discuss the phylogenetic composition of the ancient Qiang people in the settlement village, as well as a new applications of ideas for three-dimensional laser scanning technology usage in the field extraction of cultural relics. However, a follow-up study is needed to improve the comparisons of its applications, providing a conventional auxiliary means for cultural relic extraction and a technical means for cultural relic protection evaluation.

Geometric Accuracy Evaluation Method for Subway Stations Based on 3D Laser Scanning

The rapid development of three-dimensional (3D) laser scanning technology has provided a new technical means for the geometric accuracy evaluation of subway stations. With high precision and high efficiency, laser scanning technology can present the construction site condition in a panoramic way, which is essential for achieving high precision and all-round geometric accuracy evaluation. However, when the survey coordinate system of the design building information modeling (BIM) predefined in the design stage is not applied during the laser scanning data acquisition or the BIM loses the survey coordinate system during the interaction, the objects will have different coordinate positions in the point cloud and BIM, which will limit the accuracy comparison between the two data sources. Meanwhile, the existing methods mainly focus on the above overground buildings, and the accuracy evaluation of underground structures mainly focuses on the overall deformation monitoring. So far, the existing methods do not constitute a hierarchical index system to assess the geometric accuracy of various objects in the subway station. This study proposes a method to evaluate the geometric accuracy of subway stations based on laser scanning technology. A coarse-to-fine coordinate registration from point cloud to the design BIM is used to unify coordinates in different reference systems; and geometric accuracy evaluation of different structures in subway stations is achieved by developing geometric accuracy evaluation indexes and technical systems. The method is applied to the geometric accuracy monitoring of the Hongqi Road subway station, and the experimental results verify the reliability of the method.