3D Terrestrial Laser Scanning Research Articles

Solution for permanent monitoring based on RIEGL 3D terrestrial laser scanning

Solution for permanent monitoring based on RIEGL 3D terrestrial laser scanning

Historical Heritage Maintenance via Scan-to-BIM Approaches: A Case Study of the Lisbon Agricultural Exhibition Pavilion

Building Information Modeling (BIM) has emerged as a revolutionary tool in the domain of architectural conservation and documentation. When combined with terrestrial 3D laser scanning, it presents a powerful method to capture and represent the intricate details and nuances of historic structures. Such buildings, with their unique architectural lineage, often exude a geometric complexity unparalleled by standard designs. Consequently, the transition from scan data to a BIM framework, or the scan-to-BIM process, becomes intricate and time-intensive. Beyond the challenge of digital translation, the true essence of these historic buildings lies not only in their geometric form but also in understanding and preserving their design logic, formal composition rules, and primitive geometry. It then becomes imperative that the resulting model maintains fidelity in terms of proportion, shape, symmetry, and spatial rationale. Considering these challenges and potentials, this article delves into the process of digitalizing and BIM modeling of the Lisbon Agricultural Exhibition Pavilion located in Portugal. Our study proceeds in a tripartite structure: initiating with an in-depth terrestrial 3D laser scanning of the pavilion, followed by a comprehensive registration, processing, and alignment of the acquired scans, and culminating in a detailed BIM model using the industry-standard Revit 2020 software.

A Multimodal Research Approach to Assessing the Karst Structural Conditions of the Ceiling of a Cave with Palaeolithic Cave Art Paintings: Polychrome Hall at Altamira Cave (Spain).

Integrating geomatics remote sensing technologies, including 3D terrestrial laser scanning, unmanned aerial vehicles, and ground penetrating radar enables the generation of comprehensive 2D, 2.5D, and 3D documentation for caves and their surroundings. This study focuses on the Altamira Cave's karst system in Spain, resulting in a thorough 3D mapping encompassing both cave interior and exterior topography along with significant discontinuities and karst features in the vicinity. Crucially, GPR mapping confirms that primary vertical discontinuities extend from the near-surface (Upper Layer) to the base of the Polychrome layer housing prehistoric paintings. This discovery signifies direct interconnections helping with fluid exchange between the cave's interior and exterior, a groundbreaking revelation. Such fluid movement has profound implications for site conservation. The utilization of various GPR antennas corroborates the initial hypothesis regarding fluid exchanges and provides concrete proof of their occurrence. This study underscores the indispensability of integrated 3D mapping and GPR techniques for monitoring fluid dynamics within the cave. These tools are vital for safeguarding Altamira, a site of exceptional significance due to its invaluable prehistoric cave paintings.

Design Improvement for a Maritime Training Polygon using 3D Terrestrial Laser Scanning Technology

In the current geo-strategic context, the North Atlantic Treaty Organization (NATO) and the International Maritime Organization (IMO) impose increasingly high standards for seafarers' preparation in the ship's vitality training centers (elaborate constructions, designed and equipped specifically for training personnel in scenarios involving flooding and fires that may occur on board ships). The buildings housing these training areas experience considerable mechanical and thermal stress, which, over time, affects their structural integrity. Therefore, repairs and modernization work become necessary. This paper provides a case study on the application of technologies for terrestrial laser scanning of buildings, with a focus on the vitality training polygon. The originality of the approach comes from achieving "as-built" documentation for the vitality polygon using 3D laser scanning technology. This includes both three-dimensional modeling based on digital information from the scanning process, as well as structural analysis using finite element techniques for the buildings where crew training takes place. The study also analyzes the distribution of total deformations and stresses in the walls of exercise compartments for flooding and water fight scenarios. Moreover, temperature distribution in the walls and interior atmosphere of these compartments is examined for fire scenarios and firefighting.

The Gralheira lode in the territorium metallorum Tresminas/Jales. A "treasure trove" of ancient mining technology

The little-known Roman gold mining site "Gralheira" is located near the well-explored mine of Tresminas. The 2.5 km long, almost dead straight archaeological monument from the first and second centuries AD is currently under threat from possible mining activities on the one hand and from modern waste disposal in the pits on the other. Since 2019, the Roman mining traces have been investigated by means of intensive field inspections, terrestrial 3d laser scanning and aerial photography. The following article will present first impressions and findings on this structure, as well as questions and preliminary interpretations.

Contribution of Lasergrammetry, Photogrammetry and Electrical Tomography for the Survey and 3D Representation of Caves: Case Study of the Cave of Kef El Baroud, Province of Benslimane, Morocco

The modeling of caves is constantly evolving and the classic modeling tools are giving way to new techniques that are more precise and more practical, indeed scientists are increasingly using 3D modeling to improve the representations of caves, in this study we have used lasergrammetry and photogrammetry which occupy an increasing place in the 3D representation of caves. Their simplicity favors their use for recording and modeling the parietal morphology of caves and the detailed representation of the complexity of Endokarst. As part of the geomorphological study of the Kef El Baroud Cave which is located in the province of Benslimane in Morocco, two modeling methods were carried out, it is a digital survey by lasergrammetry and by photogrammetry of the cave. and its parietal morphologies. The study was completed by a topographical survey with a DistoX rangefinder. The geophysical contribution by electrical tomography was also carried out. The 3D terrestrial laser scanning technique was performed by a LEICA RTC 345 scanner. These measurements made it possible to reconstruct the evolutionary stages of the paragenetic morphologies, and their relationships with the local geomorphology, and the structural elements. The field measurements were integrated into the morphometric analyzes of the digital models, which allowed a large number of observations.The surveys also made it possible to compare the results with those of the photogrammetry carried out by a reflex camera and a wide-angle lens with appropriate editing software.Lasergrammetry and its application have enabled us to precisely position within the point cloud all the details of the covered wall, and thus constitutes, alongside photogrammetry, an interesting means for the geomorphological study of the Caves. An electrical tomography study was coupled with the other measurements and made it possible not only to delimit the walls of the Cave according to the resistivity gradients but also to detect the very probable presence of fractured zones under the Cave which could constitute an aquifer.

FAST OR EXTENSIVE? COMPARING WORKFLOWS FOR THE GEOMETRICAL ANALYSIS OF THE BUILT HERITAGE

Abstract. Three-dimensional digitization has been widely used for the documentation of built heritage. This paper presents two different approaches to the three-dimensional documentation of historic buildings using active 3D Terrestrial Laser Scanning (TLS) devices and data integration from other heterogeneous sources. Both methods aim to produce accurate and complete 3D surveys by integrating data from other sources, such as historical photographs, conservation reports, and traditional drawings, to enable a geometric analysis of the buildings. The first approach aims for completeness and redundancy of geometric information. The second method focuses on rapidness and is suitable for situations where the building is not easily accessible. The two approaches are applied to the case studies of Diotti Palace in Milan and Uzbekistan Hotel in Tashkent, demonstrating the efficiency of the two different datasets for analyzing the built heritage. The paper compares these two approaches and highlights their advantages and drawbacks in terms of the reliability of the resulting data. The study shows how two different methodologies can be adopted in different scenarios to obtain a comprehensive database for reliable and in-depth analysis of historic buildings.

Investigation of Actual In-Plane Geometric Imperfections of Steel Tied-Arch Bridges

The complex global analysis of the steel tied-arch bridges may require specific data in some cases, e.g., residual stress or real geometrical imperfections. The presented research is focused on the investigation of the actual in-plane shape of the steel tied-arch bridges. To obtain the actual shapes of the arches of existing bridges, 3D terrestrial laser scanning was applied. Data were then investigated as a group in order to find the relationship within the tied-arch bridges’ vertical imperfections. Firstly, the detailed surveyed points in the selected position were mathematically determined to estimate the measured data. The next step included the creation of curves presenting the real shape of the bridges’ arches course using numerical modelling. After the pre-programming, the calculations and related numerical modelling were performed in the Matlab environment. These modelled arch-bridges courses were approximated by using regression analysis. The approximating curves from the regression analysis represent the theoretical course of the arches. The difference between the theoretical shape and the processed measured values may be presented as the examined in-plane imperfections. Subsequently, the paper presents comparisons from the evaluation of the individual imperfections on the investigated bridges and a comparison of the measurement with the standardised shape of the imperfections.

Integration of Remote-Sensing Techniques for the Preventive Conservation of Paleolithic Cave Art in the Karst of the Altamira Cave

Rock art offers traces of our most remote past and was made with mineral and organic substances in shelters, walls, or the ceilings of caves. As it is notably fragile, it is fortunate that some instances remain intact—but a variety of natural and anthropogenic factors can lead to its disappearance. Therefore, as a valuable cultural heritage, rock art requires special conservation and protection measures. Geomatic remote-sensing technologies such as 3D terrestrial laser scanning (3DTLS), drone flight, and ground-penetrating radar (GPR) allow us to generate exhaustive documentation of caves and their environment in 2D, 2.5D, and 3D. However, only its combined use with 3D geographic information systems (GIS) lets us generate new cave maps with details such as overlying layer thickness, sinkholes, fractures, joints, and detachments that also more precisely reveal interior–exterior interconnections and gaseous exchange; i.e., the state of senescence of the karst that houses the cave. Information of this kind is of great value for the research, management, conservation, monitoring, and dissemination of cave art.

Slope gradient impacts on rill morphological characteristics: Using indoor simulation experiment on loamy clay under certain rainfall intensity

In the present study, the rill morphological parameters and their spatial distributions were investigated using indoor rainfall simulation experiments in combination with 3D terrestrial laser scanning technique. Moreover, the optimal rill morphological indicators for rill erosion evaluation were selected based on the relationship of rill morphological parameters and erosion amount. The results showed that total rill length (L), rill density (ρ), maximum width (Wmax), the degree of contour line departure (μ) and shape ratio (η) increased with the increase of slope gradient, whilst the mean rill depth (Dmean), mean rill width (Wmean) and width/depth ratio (W/D) decreased with the increase of slope gradient. The spatial distribution pattern of each rill morphology parameter was also changed with slope gradient, showing differences in upper slope, central slope and lower slope. Most of rill morphological parameters were highly correlated with rill erosion amount, except the mean rill width (Wmean), degree of contour line departure (μ), and rill density (ρ). The plane area of rill (Parea) or the degree of rill dissection (δ) was selected as the optimal morphological parameter to predict rill erosion amount, followed by the maximum area of cross section (CSmax), the maximum rill depth (Dmax), and the mean rill depth (Dmean). In particular, the parameters of CSmax and Dmax are recommended for rill erosion estimation based on the convenience and ease of data acquisition.

3D model-based terrestrial laser scanning (TLS) observation network planning for large-scale building facades

Planning a terrestrial laser scanning (TLS) observation network is vital for capturing large-scale building facade point clouds with high time efficiency and high quality. However, existing planning methods are susceptible to low reliability, computational burden and lack of robust registrability assessment solutions, especially for a large-scale task. Therefore, this paper proposes a 3D model-based TLS observation network planning method for large-scale building facades. Firstly, a simple 3D model is quickly obtained by low-cost unmanned aerial vehicle (UAV) photogrammetry. Secondly, a fast scanning simulation of TLS candidate scan positions is performed. Finally, the TLS network is generated by a weighted greedy algorithm and a registration assessment method. Comprehensive experiments based on simulation and real scanning were conducted for validating the proposed method. Results demonstrated that the planned TLS network was efficient in various complex scenes. Moreover, the proposed method outperformed the 2D model-based method in terms of reliability.

Comparative Study of the Representative Algorithms for Fitting Spherical Target Based on Point Cloud

Spherical target fitting (STF) is a challenging problem in terrestrial 3D laser scanning applications, and many algorithms have been developed for this task. This paper aims to address the issues, including how to find the proper algorithm for the specific requirements from the existing algorithms, what influencing factors should be considered when utilizing those algorithms, and how to improve them further, etc. We classify the existing STF algorithms into least squares (LS) and numerical optimization (NO) categories and select seven representative algorithms as major research objectives. Based on the dissection of their fundamental principles, we comprehensively verify the selected seven algorithms using simulated and field data, respectively. The experimental findings reveal that the linear least squares (LLS), orthogonal non-linear least squares (ONLS), and gradient descent (GD) have high computational efficiency; however, they are sensitive to noise and coverage. General total least squares (GTLS) has a certain degree of noise immunity but suffers from low efficiency and the constructed stochastic model. By introducing specific constraint rules, M-estimate sample consensus (MSAC) and feature-constrained random search (FCRS) may provide higher-precision fitting results, but indicate obvious instability and unreliability. Feature-constrained grid search (FCGS) can achieve good results in most cases in the usage of feature constraints and uniform sampling, but still presents drawbacks under the severely ill-conditioned situation. Additionally, comprehensive analysis indicates that the accuracy and robustness of the STF algorithms are influenced by noise and coverage, whereas computational efficiency is primarily affected by the number of measurement points.

Automatic Pairwise Coarse Registration of Terrestrial Point Clouds Using 3D Line Features

The fully automatic registration of 3D terrestrial laser scanning (TLS) point clouds, which is the first step in the usage of point clouds, is a highly challenging task in Light Detection and Ranging (LiDAR) remote sensing applications. Here, an automatic algorithm for pairwise coarse registration of TLS point clouds using 3D line features is proposed. First, the 3D line sets were extracted from the original pair of point clouds respectively, and two arbitrary lines from a point cloud were used to construct a 2-line base; Then, a pair of conjugate 2-line bases were identified from the source and target 3D line sets at a time, based on which a 3D rotation matrix together with its corresponding overlap between the pairwise 3D line sets was calculated; Third, a series of 3D rotation matrixes together with their overlaps were obtained using the traversing strategy to identify conjugate 2-line base pairs, and the 3D rotation matrix with the highest overlap was outputted as the final 3D rotation matrix, which was further used to compute the corresponding lines set from the pairwise 3D line sets; Next, based on the set of common perpendicular midpoints between the line correspondences, the 3D translation vector was computed; Finally, the 3D transformation matrix between pairwise point clouds was obtained by combining the 3D rotation matrix and the 3D translation vector. The proposed method was tested on three different TLS datasets, with experimental results demonstrating that the proposed algorithm could perform well on registering pairwise TLS point clouds. The rotation and translation errors of aligning the nine experimental pairwise point clouds were all less than 0.50° and 0.55m, respectively. This registration framework was also shown to be superior to state-of-the-art methods in terms of registration accuracy.

Assessment of a Rock Pillar Failure by Using Change Detection Analysis and FEM Modelling

In this paper, various methods have been used to control and evaluate engineering difficulties in mining accurately. Different unstable scenarios occurring at the surfaces of underground mine walls, have been identified by comparing 3D terrestrial laser scanning surveys and subsequent point cloud 3D analysis. These techniques, combined with a change detection analysis approach and the integration of rock mechanics’ modelling, represent an asset for the assessment and management of the risk in mining. The change detection analysis can be used as control of mining and industrial processes as well as to identify valid model scenarios for establishing possible failure causes. A pillar spalling failure has been identified in an Italian underground marble quarry and this topic represents the basis of the present paper. A Finite-Element Method was used to verify the occurrence of relatively high-stress concentrations in the pillar. The FEM modelling revealed that stresses in the proximity of the pillar may have sufficient magnitude to induce cracks growth and spalling failure.

A Survey of Scan-to-BIM Practices in the AEC Industry—A Quantitative Analysis

Architectural survey methods using terrestrial 3D laser scanning and digital photogrammetry prove capable of registering a building with a level of accuracy far superior to traditional methods, minimizing errors, and reducing fieldwork. Current developments in the construction industry, and new requirements emerging worldwide, have increased the demand for building information modeling (BIM) models as the end product of these surveys. Still, because BIM is a new paradigm, many professionals find the transition challenging, especially when dealing with old and heritage buildings. The new ways of the market demand solutions to optimize processes and make architectural reconstruction from point clouds even more efficient. An online questionnaire survey was carried out with 208 industry professionals working in 78 countries to assess the scope of these demands. As a result, the article presents an overview of current scan-to-BIM practices worldwide with data regarding the architectural survey and BIM modeling derived from point clouds. The implemented survey also identifies in which countries BIM adherence is most accelerated for conventional buildings and for listed buildings and non-listed old buildings, the main benefits and difficulties encountered by professionals, tools and workflows used, and the role of different professionals in collaborative work.

APPLICATIONS OF TERRESTRIAL LASER SCANNING (TLS) IN MINING: A REVIEW

This study investigates in depth Terrestrial Laser Scanning technology (TLS), its working and measurement principle, 3D Terrestrial Laser Scanning softwares and the advantages of this scanning method. This paper also stresses the advantages of adopting this technology in quarries and mines and provides examples of researches that have demonstrated the superiority of TLS systems over the traditional scanning methods in terms of practicability, reliability and accuracy in numerous mining engineering applications such as deformation measurements, rock fall and landslide control, volume calculations and detection of discontinuities.

Possibility of convergence measurement of gates in coal mining using terrestrial 3D laser scanner

Possibility of convergence measurement of gates in coal mining using terrestrial 3D laser scanner

A Comparison Method for 3D Laser Point Clouds in Displacement Change Detection for Arch Dams

Dam deformation monitoring can directly identify the safe operation state of a dam in advance, which plays an important role in dam safety management. Three-dimensional (3D) terrestrial laser scanning technology is widely used in the field of deformation monitoring due to its fast, complete, and high-density 3D data acquisition capabilities. However, 3D point clouds are characterized by rough surfaces, discrete distributions, which affect the accuracy of deformation analysis of two states data. In addition, it is impossible to directly extract the correspondence points from an irregularly distributed point cloud to unify the coordinates of the two states’ data, and the correspondence lines and planes are often difficult to obtain in the natural environment. To solve the above problems, this paper studies a displacement change detection method for arch dams based on two-step point cloud registration and contour model comparison method. In the environment around a dam, the stable rock is used as the correspondence element to improve the registration accuracy, and a two-step registration method from rough to fine using the iterative closest point algorithm is present to describe the coordinate unification of the two states’ data without control network and target. Then, to analyze the displacement variation of an arch dam surface in two states and improve the accuracy of comparing the two surfaces without being affected by the roughness of the point cloud, the contour model fitting the point clouds is used to compare the change in distance between models. Finally, the method of this paper is applied to the Xiahuikeng Arch Dam, and the displacement changes of the entire dam in different periods are visualized by comparing with the existing methods. The results show that the displacement change in the middle area of the dam is generally greater than that of the two banks, increasing with the increase in elevation, which is consistent with the displacement change behavior of the arch dam during operation and can reach millimeter-level accuracy.

Multi-temporal estimation of vegetable crop biophysical parameters with varied nitrogen fertilization using terrestrial laser scanning

Estimation of biophysical parameters at various crop growth stages is vital for precision agricultural crop production. Spatial delineation of crops’ responses to various levels of nutrients helps optimise resources and reduce nutrient leaching. This paper explores the potential of 3D terrestrial laser scanning (TLS) for the estimation of plant height, crown area, and biomass of vegetable crops at various N levels. Experimental setup of growing three vegetable crops: tomato (Solanumlycopersicum L.), eggplant (Solanummelongena L.) and cabbage (Brassica oleracea L.) with three levels of N fertilization was laid out at the University of Agricultural Sciences, Bengaluru, India in 2017. LiDAR point clouds using a terrestrial laser scanner were collected at different growth stages. A methodology which included, among other processing steps, adaptive spatial filtering, canopy height modelling, watershed segmentation, and support vector regression has been adapted for the estimation of plant height, crown area, and biomass. Validation with ground measurements show high prediction accuracies for plant height (lowest coefficient of determination (R2), 0.96; highest symmetric mean absolute percentage error (SMAPE) of 3.18), and crown area (lowest R2, 0.82; highest SMAPE, 8.82) for all the three crops across growth stages. The combined use of plant height and the crown area has enabled accurate and consistent estimation of biomass (lowest R2, 0.92; highest SMAPE, 7.53) throughout the growing season. However, the mapping of a specific range of biomass to a specific N level is ambiguous due to wider variations in the crop growth due to rainfall, and wind interferences.

Research on Building Measurement Accuracy Verification Based on Terrestrial 3D Laser Scanner

The accuracy of terrestrial 3D laser scanners is mainly determined by the accuracy of ranging and angle measurement. Therefore, the research of horizontal angle accuracy is very important. The current construction industry can develop at the fastest speed because of the advent of many advanced science and technology research and development. The rational application of these science and technology to the construction industry can intuitively display the internal structure and external shape of the building. In front of people, it effectively guarantees the country's economic benefits and the people's property safety. The article studies the influence of distance, incident angle and target color on the accuracy of the scanner during measurement. Using the plane fitting method to analyse the accuracy, a qualitative analysis conclusion is drawn that as t he distance increases, the angle of incidence increases, which will cause the measurement accuracy of the ground 3D laser scanner to decrease.