Ground Laser Scanning Research Articles

Automated Estimation of Building Heights with ICESat-2 and GEDI LiDAR Altimeter and Building Footprints: The Case of New York City and Los Angeles

Accurate estimation of building height is crucial for urban aesthetics and urban planning as it enables an accurate calculation of the shadow period, the effective management of urban energy consumption, and thorough investigation of regional climatic patterns and human-environment interactions. Although three-dimensional (3D) cadastral data, ground measurements (total station, Global Positioning System (GPS), ground laser scanning) and air-based (such as Unmanned Aerial Vehicle—UAV) measurement methods are used to determine building heights, more comprehensive and advanced techniques need to be used in large-scale studies, such as in cities or countries. Although satellite-based altimetry data, such as Ice, Cloud and land Elevation Satellite (ICESat-2) and Global Ecosystem Dynamics Investigation (GEDI), provide important information on building heights due to their high vertical accuracy, it is often difficult to distinguish between building photons and other objects. To overcome this challenge, a self-adaptive method with minimal data is proposed. Using building photons from ICESat-2 and GEDI data and building footprints from the New York City (NYC) and Los Angeles (LA) open data platform, the heights of 50,654 buildings in NYC and 84,045 buildings in LA were estimated. As a result of the study, root mean square error (RMSE) 8.28 m and mean absolute error (MAE) 6.24 m were obtained for NYC. In addition, 46% of the buildings had an RMSE of less than 5 m and 7% less than 1 m. In LA data, the RMSE and MAE were 6.42 m and 4.66 m, respectively. It was less than 5 m in 67% of the buildings and less than 1 m in 7%. However, ICESat-2 data had a better RMSE than GEDI data. Nevertheless, combining the two data provided the advantage of detecting more building heights. This study highlights the importance of using minimum data for determining urban-scale building heights. Moreover, continuous monitoring of urban alterations using satellite altimetry data would provide more effective energy consumption assessment and management.

Mapping Longitudinal and Transverse Displacements of a Dam Crest Based on the Synergy of High-Precision Remote Sensing

Reservoirs are highly relevant infrastructure assets, and now, more than ever, they play an essential role in society’s welfare and national security. Their importance is related to regional socioeconomic development due to their capacity to store water for different uses, such as human consumption, agricultural irrigation, flood control, and hydroelectric energy production, among other important services. However, many reservoirs are reaching the end of their period of life, and others are showing undesired displacements and cracking. Four 3D surveys were conducted on a reservoir that serves the Metropolitan Area of Monterrey City in Mexico. These surveys were carried out over a period of 5 years using GNSS observation to assist in understanding the actual dam kinematics, i.e., the behavior of its longitudinal and transversal displacements and the possible correlation with the reservoir level. The high-precision leveling and close-range remote sensing data were assessed and then mapped. The high-precision geodetic and leveling techniques allowed us to locate and measure 84 established permanent control points with errors of about ± 0.003 m. The mapping of displacements was made possible by modeling the positive and negative translations. The highest uplifts (11 mm) occurred at the left riverbank, and the highest subsidences (−5 mm) occurred along the downstream piers from the middle of the dam crest to the right riverbank. A ground laser scanner (GLS) produced 3D digital models with geometrical and radiometric characteristics, detecting displacements among the dam crest elements. The synergy of GNSS and high-leveling techniques allows the possibility to measure displacements, while the use of geographical information system (GIS) and geomatic techniques allows a better visualization through 2D and 3D maps validated using traditional topographical methods.

Створення тривимірної моделі культової споруди за даними комбінованих геодезичних знімань

The purpose of the research is to test algorithms for creating a three-dimensional model of an object based on point clouds obtained from combined geodetic surveys (UAV survey and ground laser scanning). The methodology is based on the collection of a cloud of points by ground laser scanning and the acquisition of a cloud of points on the same object by the photogrammetric method based on data taken from a UAV. The formation of the resulting three-dimensional model is performed according to the most reliable data from the point of view of geometric accuracy. The results. Each of the point cloud acquisition methods (UAV or laser scanning) has its advantages for certain parts of the building. Thus, the modeling of the upper part of the building, sloping and complex roofs is best performed based on the data taken from the UAV, vertical walls and the elements placed in them (windows, decoration elements, etc.) – based on point clouds obtained from laser scanning. Scientific novelty and practical significance. The method of processing point clouds obtained from various sources on the basis of free software was tested. The approach discussed in the article has significant potential for use in many branches of the national economy. The performer can combine measurement data from various sources on the basis of free software and prepare them for further export to the necessary software for creating a model.

Ground laser scanning of the flyover through the railway for the purposes of its reconstruction

The article presents the possibility of obtaining geometric parameters of an flyover passing through a railway using ground–based laser scanning technology using modern equipment Leica Scan Station C10. The practical significance of using the chosen method lies in the fastest and most convenient scanning of the object, reducing production costs and, of course, high accuracy of the spatial data obtained necessary for the reconstruction of the flyover. A study of the use of ground-based laser scanning technology to obtain spatial data of the flyover was conducted, as a result of which the advantages of the chosen method were revealed. Also, based on the data obtained, a comprehensive three-dimensional model and two-dimensional drawings were prepared, such as the facade of the flyover, its plan and drawings of transverse profiles. Thanks to the compiled drawings and models of the bridge structure passing through the railway, the design work on the reconstruction of the facility has become much easier and more efficient. The presented experience confirms the need to introduce modern technologies, namely ground-based laser scanning in survey activities in order to develop and detail design solutions for the reconstruction of flyovers.

Estimating Riparian Vegetation Volume in the River by 3D Point Cloud from UAV Imagery and Alpha Shape

This study employs technology that has many different applications, including flood management, flood level control, and identification of vegetation type by patch size. Recent climate change, characterized by severe droughts and floods, intensifies riparian vegetation growth, demanding accurate environmental data. Traditional methods for analyzing vegetation in rivers involve on-site measurements or estimating the growth phase of the vegetation; however, these methods have limitations. Unmanned aerial vehicles (UAVs) and ground laser scanning, meanwhile, offer cost-effective, versatile solutions. This study uses UAVs to generate 3D riparian vegetation point clouds, employing the alpha shape technique. Performance was evaluated by analyzing the estimated volume results, considering the influence of the alpha radius. Results are most significant with an alpha radius of 0.75. This technology benefits river management by addressing vegetation volume, scale, flood control, and identification of vegetation type.

Innovative approach for surveying slope stability in road infrastructure rehabilitation

The objectives of the repair, maintenance and rehabilitation of the road network in mountainous terrains focus on the study of the structural condition of the rock slopes. An innovative approach to structural mapping and analysis was implemented within the framework of a survey project for a road section of road II-35 Troyan-Karnare, known as “BEKLEMETO”. This section begins with a long and steep descent from the Beklemeto saddle (at 1,525.5 m above sea level), passes through numerous bends on the southern rocky slope of the mountain and after 22.7 km descends into the northwestern part of the Karlovska valley, to the village of Karnare (at 562 m above sea level). The study of the structural disturbance provides an opportunity to present the groups of joints that have developed intensively on the rock slopes passing near the Republic Road II-35 in the section between Beklemeto and Karnare. Over the years, these slopes have been subjected to weathering, erosion and collapse processes, which have led to changes in the physical and mechanical properties of the rocks forming the slopes. The technology of mobile ground laser scanning, which is a suitable method for covering the complex characteristics of the terrain, was chosen for the research. The implementation of this technology was carried out through an integrated complex. Using this method, a total of 18 representative sections within the road II-35 “BEKLEMETO” were studied, and the number of measured cracks exceeded 13,000. The total length of the researched sections is over 10,770 m. In processing, short cracks with a length of less than 0.8 m, which do not affect the structural disturbance of the rock formations, are excluded. These data and studies are essential for the planning of effective measures to maintain and rehabilitate road infrastructure in complex mountain conditions.

Inspection of flatness and levelness of construction surface using terrestrial laser scanner according to ASTM E1155 standard

The flatness of the surface is one of the important indicators to access the quality of the concrete surface during and after the construction process. The terrestrial laser scanner with many outstanding advantages in accuracy, high point density and high data rate acquisition has become an effective tool for construction quality inspection. The most advantage of the ground laser scanner for assessment of floor flatness compared to traditional methods is so quickly data acquisition and able to measure when the concrete floor is still wet. This allows the contractor to identify and fix the errors without waiting for the floor to dry so it can reduce both costs and time for construction. However, in Vietnam today, there is still a lack of standards as well as technical guide to apply this technology in evaluating the flatness of the surface construction effectively. The article proposes a four-step procedure to access the flatness using a laser scanner based on the ASTM E1155 standard. The field work is carried out by using GLS 2200 scanner and uses the four-step procedure to evaluate the surface flatness of the construction. From experimental results, it can be confirmed that the above four-step proposed procedure is suitable to evaluate the flatness of the surface construction by laser scanner in Vietnam conditions. The article is an initial study from theoretical analysis, development of procedure and field work. Therefore, the article can be used as a technical guide for geodetic engineers in the quality control constructionas well as a reference for state management agencies in making standard for the assessment of surface flatness using terrestrial laser scanner.

Tools and methods of 3d scanning for creating phantom models of architectural objects

The article describes the latest innovative 3D technologies in the architectural activity of fixing and preserving architectural objects. The basic principles and methods of obtaining physical data about a certain object using 3D scanning, photogrammetry, thermal imaging and other means are given. Processing, analysis and integration in BIM and GIS systems. Method of using data from Point Cloud, BIM & GIS systems during architectural design. This article also provides an example of the use of equipment from the developer Leica, namely the ground laser scanning devices Leica RTC 360 and BLK 360. The process of obtaining data of an existing building, data processing in specialized software tools, outputting data for further use in BIM/CAD programs is described. , creating a 3D model in BIM/CAD programs (Revit/Sketchup), creating photorealistic images, as well as creating an interactive virtual model based on 3D, with the possibility of connecting VR equipment. BIM scanning plays a special role in restoration processes and related types of work, when it is necessary to investigate and record a historical building for preventive purposes, later - to create a BIM model, to investigate structures and energy efficiency after restoration. The creation of several BIM options for reconstruction or fixation, conservation or revitalization of a certain object allows you to choose the best option and subsequently speed up the process of creating technical documentation. Implementation of 3D scanning methods is a promising direction of digitalization of architectural objects. It provides opportunities to create a preventive database of phantom models of objects for their reproduction after the end of hostilities and a promising direction for the development of new technologies for performing repair and restoration works.

Application of 3-D Ground Laser Scanning Technology to Measure The Scenic Spot of The Best Spring in the World

This paper introduces the main types of 3-D ground laser scanners in the field of surveying and mapping, provides a technical scheme of applying 3-D laser scanning technology to measure ancient buildings in scenic spots, and uses the pulsed 3-D laser scanner which can transmit and receive infinite echoes to solve the problem that vegetation in the surveying area seriously blocks buildings. As an example, the feasibility of the proposed technical scheme is confirmed and the reliability of the proposed technical scheme is demonstrated by precision verification experiments at the scenic spot of the best spring in the world.

INVESTIGATION OF THE EFFECT OF CLAPS ON THE STRESS-STRAIN STATE OF TANK STRUCTURES

The need to study the problems of reliable operation of the reservoir system is relevant. Special attention should be paid to the specifics of the operation of oil storage tanks and their equipment. The Russian tank farm was formed in the 1970s, a significant part of it has a service life of more than 50 years. The experience of examining such structures with a long service life indicates the presence, in most cases, of the physical aging of their structural elements.
 The article presents the results of processing a cloud of points created using a ground laser scanner to determine the actual geometric deviations of the reservoir and their combined effect on the reliability of the reservoir.
 During the survey, a method of work was used that differs from the standard. In the field, a laser scanner was used instead of a theodolite; in office processing, software systems were used that simplify the tasks.
 In the process of research in the 3DR software package, a triangulation mesh model was created from a cloud of points from a set of finite elements to identify defects located on the wall. The data obtained can be compared with previous and future survey results. Also, the model can be used to create a calculation scheme in PC LIRA 10.
 We set the actual characteristics of the tank wall to the finite elements (the thickness of the first belt is 12 mm, the next ones 10 mm). The main load combinations were applied to the tank. The calculations were carried out for a combination of loads, including the own weight of the structures, the pressure of the stored product and the overpressure in the gas space. Circular and equivalent stresses according to the 4 (energy) theory of strength were analyzed.
 The use of a laser scanner and software systems reduces labor costs for tank inspection, improves the quality of work performed, makes it possible to see the real surface of the tank and take into account defects in the aggregate.
 This method is of practical importance and is currently used by the Department of Inspection of Buildings and Structures.

Порівняння 3D-моделей об’єктів, побудованих за матеріалами наземного лазерного сканування

The purpose of the work was to assess the accuracy and functionality of the 3D model obtained as a result of the 3D scanning and post-processing. The article discusses 3D modeling methods and their characteristics. The procedure for working with a 3D scanner is studied and its principle of operation is given. Scan data was post-processed to create 3D models of varying accuracy. The equipment used for the scanning is a FARO Focus Laser S150 terrestrial laser scanner. SCENE was used for post-processing. The object for scanning with a ground laser scanner was six identical logs of wood. The functionality and accuracy of the models are determined. Three-dimensional scanning of the research objects was carried out from six stations to obtain a full-fledged point cloud. At each station, the device was installed in the working position on the horizontal level using the inclinometer readings. Scanning was performed after selecting the appropriate shooting mode. It was taken into account that during scanning, no object can touch the mirror unit, because during operation, the scanner rotates clockwise by 180 degrees. Scanning in this study was carried out in color, so the scanner rotated 360 degrees. Based on ground laser scanning data, 3D models of cut tree trunks of the same size were built. All models are built with different accuracy for comparison and determination of the optimal one in terms of reliability and load. The obtained research results, as well as the technique itself, can be used in forestry by forestry and various structures related to wood analysis. Also, if we consider only our industry, the research data can be useful for the cadastre of park territories, etc. In the course of the conducted research, 3D models with different accuracies and memory volumes were obtained, which can be used to solve the relevant tasks. The functionality of using models consists in choosing the number of polygons that will affect the amount of memory. It should be noted that the functionality of the models lies in the convenience of their use on any device, compared to point clouds, which are demanding on the hardware component of a computer. The accuracy of the models is high in all cases. This makes it possible to use them to solve many problems, taking into account the needs. So, we can conclude that the use of models is relevant due to high accuracy and functionality.

Методика геодезического мониторинга за насыпными гидротехническими сооружениями

Bulk hydraulic structures, such as dams and dams of tailings and ash dumps are very widespread and are hazardous production facilities. The article analyzes the existing methods of geodetic monitoring of bulk hydraulic structures, their advantages and disadvantages are considered. For monitoring bulk hydraulic structures, a new technique is proposed, in which the main type of geodetic monitoring is ground laser scanning, which allows the determination of both displacement vectors for individual points and areal deformations that can be analyzed using map algebra. To highlight the surface of the dam, filtering is used according to the molding method, which allows us to clear the cloud of points of laser reflections from vegetation. Since the enclosing dams are long, it is proposed to localize the scanning sites using geotomographic studies, which make it possible to identify areas of structural het-erogeneities in the body of the dam, voids and areas of highly moistened rocks. For visual inspection of hydraulic structures, it is proposed to use unmanned aerial photography, with which you can get a three-dimensional model of the body of the dam. The dam body model can be used for finite element modeling of stresses and filtration processes in the dam body. The article provides a database diagram of the "Dam deformation" software package, which allows you to store complex information about a hydraulic structure and use it to make decisions about the state of the object.

Оперативный геодезический контроль деформаций призабойной зоны при инновационных технологиях проходки туннелей

Purpose: To consider the issue on performance of operational control of deformations of tunnel bottomhole zone with the use of ground-based laser scanning technology when tunneling with New Austrian tunneling method which is the most progressive one and feasible in economics terms for underground building construction by mining. The essence of this method is in that as a support for tunnel bottom-hole zone, a self-supporting shell made of sprayed concrete without traditional fastening method usage is applied that allows to save time for tunneling significantly, especially of those tunnels which have complex geometry and non-standard dimensions. At the same, the conceptual basis for this method is the necessity to identify operatively bottomhole zone soil mass deformations that’s justified by the need to provide job realization safety. Methods: As a major method for to determine tunnel bottomhole zone geospatial position it is proposed to consider ground-based laser scanning technology. Scanning result processing was implemented in specialized software package Leica Cyclone 3DR. Results: Existing experience of geodetic check of deformations in tunneling by New Austrian method is considered. Processing results for data on ground laser scanning of a tunnel separate fragment are presented, a tunnel mathematical three-dimensional model is obtained and assessment of deviations of tunnel actual surface from obtained theoretical one is fulfilled. Practical significance: The obtained threedimensional model can be further used for geodetic monitoring of deformations. Theoretical bases for estimation required accuracy for deformation characteristics definition are substantiated which are based on the transition from construction tolerances to average quadratic errors of deformation characteristics definition and then to average quadratic errors of coordinates for laser scanning points. The enlarged stages of scanning are defined with view of tunneling technology of New Austrian method.

Інвентаризація об’єктів садово-паркового господарства скверу Т. Масарика м. Ужгород із використанням НЛС

Goal. The aim of the work was to show the main stages and prospects of analysis of the obtained data of ground laser scanning of small groups of green areas of cities on the example of T. Masaryk Square in Uzhgorod, as well as to compare this technology with the classical method of inventory of green areas..Method. The paper highlights the features of the inventory of garden and park facilities using ground-based laser scanning (NLS). The method of not only determination of existence of objects of green economy but also their characteristics is offered. The inventory of green plantations and the results of its application are described on the example of T. Masaryk Square in Uzhhorod. A comparison of inventory data collected by analog methods in 2017 and NLS data in 2021. Inventory of green plantations is carried out in accordance with the Instruction on technical inventory of green plantations in cities and towns of Ukraine every five years from April to October and provides: determination of the total area occupied by green facilities, including trees, shrubs , flower beds, lawns, trails, etc .; determination of the number of trees and shrubs by types of plantings, species, age, diameter at a height of 1.3 m of tree trunks and the state of their content; determining the value of the object as a whole and its individual areas; timely introduction of changes that have taken place in green areas, in drawings, passports of green facilities and summary data on green areas of the settlement. During the inventory, the following was carried out: determination of the total area occupied by green facilities, including trees, shrubs, flower beds, lawns, paths, etc .; determination of the number of trees and shrubs by type of plantings, species, age, diameter at a height of 1.3 m of tree trunks and the state of their maintenance; determining the value of the object as a whole and its individual areas; timely introduction of changes that have taken place in green areas, in the drawings, passports of green facilities and summary data on greenery of the settlement. Results. As a result of the research, a laser scan of T. Masaryk Square in Uzhhorod was performed and the obtained data were processed. A detailed inventory of greenery on the Independence Embankment, namely on the territory of the memorial square. Masaryk. After sub-tree accounting, 106 tree species of different species were studied. Conifers – 3 species, deciduous – 12. During the inventory of sanitary conditions, the following number of trees in each category: I category -49; II category – 33; III category – 1; IV category – 27; V category – 1. The general sanitary assessment of plantings is satisfactory with insignificant drought and emergency plantations of white poplar that need to be replaced.. Practical value. The obtained results can be used by the municipal authorities to tidy up and take care of T. Masaryk Square in Uzhhorod.

STUDY ON THE CORRELATION BETWEEN EMERGENCY MONITORING AND GUIDANCE OF POST DISASTER LANDSLIDE AND POST DISASTER ANXIETY BASED ON REMOTE GROUND LASER SCANNING

BackgroundWith the rapid development of China's national economy, people pay more and more attention to disaster prevention and reduction and the impact of landslide disasters. Before the construction of various projects, disaster investigation, assessment and prediction shall be carried out to avoid in advance as much as possible, or necessary preventive measures shall be taken to prevent and reduce the occurrence of disasters as much as possible. The internal causes and treatment of landslide are studied from the aspects of point-to-point, line surface comprehensive prediction and disaster prevention and control. At the same time, the landslide damaged by high-speed and long-distance is also deeply studied. In particular, the prediction of landslide occurrence time has made a breakthrough, forming a theoretical system from treatment to prevention. However, the landslide geological disaster directly endangers the production and life of the people in the disaster area and causes psychological trauma. Accurate monitoring of micro deformation before landslide is of great significance to landslide early warning system. When using ground laser scanning (TLS) technology for landslide monitoring, the traditional point cloud data processing results, that is, comparing the changes of landslides between different surfaces, have a great deviation from the actual monitoring values.Research Objects and MethodsThis paper proposes a method to compare landslide changes by extracting the surface feature points of the monitoring object, and designs two verification experiments, namely Experiment 1 carton tilt change experiment under different design angles and Experiment 2 landslide physical model experiment. Then, in two experiments, this method is used to extract feature points with the same name. Finally, the change of inclination and the settlement of landslide are calculated. In order to test the impact of emotional behavior, this study selected subjects stimulated after the disaster, and selected 60 subjects, including 30 men and 30 women. We used the anxiety scale designed by Kim as the measurement scale, and evaluated the scale by Likert scoring method. Pearson correlation, standard deviation and statistical significance were used to illustrate the correlation. Independent sample t-test was used to verify the difference between high anxiety group and low anxiety group. According to the statistical value of anxiety, participants were divided into three groups: low, medium and high anxiety groups. The questionnaire includes two kinds of anxiety, namely debilitating anxiety and promoting anxiety. The relationship between anxiety and self-efficacy of subjects with different majors and genders was investigated by t-test, univariate, multivariate analysis of variance and regression analysis.ResultsUsing the method proposed in this paper, the change of carton inclination in Experiment 1 and the settlement of landslide surface in different periods in Experiment 2 are obtained, and the error of the results is analyzed to verify the feasibility of the method proposed in this paper. Test participants can effectively alleviate psychological stress and prevent depression. The data showed that the DASS-21 comprehensive score of subjects participating in the test was 1.7 times that of subjects not participating in the test. In contrast, without participation, they are more likely to show depression, anxiety and stress, and tend to be passive in simple coping styles. The improved method can effectively alleviate the psychological pressure of employees and improve the ability to actively deal with pressure. Through the correlation analysis of emotion regulation ability, the data results show that structural equation model is used to investigate the mediating role of core self-evaluation and emotion regulation self-efficacy between stressful life events and life satisfaction. The maximum likelihood estimation method is used to estimate the intermediary effect. The results show that the fitting indexes of this model are χ 2=314.015, df=218, χ 2/df=1.44, CFI=0.958, TLI=0.94, RMSEA=0.043. All paths in the model are significant. According to the effect decomposition principle of path analysis, the total effect from stressful life events to life satisfaction is equal to direct effect plus indirect effect. The total indirect effect in this study is equal to the sum of three specific mediating effects, which is -0.299. The proportion of indirect effect in the total effect is -0.299 / (-0.469) + (-0.299) = 0.389, that is, 38.9% of the effect of stressful life events on life satisfaction is through core self-evaluation and emotion regulation self-efficacy.ConclusionUsing the method proposed in this paper, the visual expression of the internal cause of landslide is realized. This method can calculate the displacement and inclination of key parts in different periods, and obtain the stable state of the monitoring object through comparative analysis. It is consistent with the traditional analysis method, but it improves the efficiency and accuracy, provides reliable data support for the subsequent landslide prediction, and avoids people's property loss and psychological trauma to the greatest extent.AcknowledgementThis work was financially supported by the Research Foundation of Education Bureau of Jiangxi Province, China (No. GJJ190944) and the National Natural Science Foundation of China Regional Science Fund Project (42162023).

APPLICATION OF CONSUMER–LEVEL UAV PHOTOGRAMMETRY IN DIGITAL SURVEY OF CLIFF-BURIAL CULTURE RELICS: A CASE STUDY OF MOUNT WUYI

Abstract. The cliff-burial was an ancient funerary ritual once popular in the Far East Asia (Figure 1), in which the dead were buried high on the cliffs with log coffins (the “hanging coffins”) left in the natural caves, excavated grottoes or on some wood piles.In view of the fact that the cliff-burial sites are usually located on the escarpments overlooking the rivers and with great slope, where the conventional 3D survey means, such as ground laser scanning and traditional aerial photogrammetry, is out of option. This study explores the possibility of using UAV (consumer–level drone) with substantial improvement in survey accuracy, range and flight control (Figure 2), which aims to lay the foundation for the global cliff-burial culture heritage research. A survey method extendible on other excavated funeral sites would be tested and codified, as a possible follow up of the research on some study cases in Far East Asia and Europe.

Analysis of the displacements of pipeline overpasses based on geodetic monitoring results

There are many approaches to address geospatial monitoring of pipeline overpasses, among which the most widespread methods are terrestrial laser scanning and total station measurements. However, there is a problem in comparing the geospatial monitoring data collected by different methods in different epochs. The main task of this work is to find the correspondence between points in different epochs. The total station measurements are carried out in specific discrete points of the pipeline overpass. In contrast, terrestrial laser scanning allows the collection of the whole data set without fixing specific point coordinates. In order to compare different data in different epochs, it is necessary to select a relevant presentation of the monitoring results (reference model) and specify appropriate criteria for quality inspection. In general, a pipeline can be presented as a spatial curve. In this study, two types of reference models are considered: cubic splines and Bezier curves. These models are examined for the monitoring of two gas pipeline overpasses. The first measurement epoch is accomplished by the terrestrial laser scanning, and the second measurement epoch is completed by the total station. The reference models are simulated by Matlab coding. The preliminary accuracy of ground laser scanning and total station measurement is selected as the criterion of quality inspection. The simulation and comparison results provide the evidence that the correct selection of reference model is a crucial component of successful geospatial monitoring. The results show that the Hermite splines are effective in the comparison of different data sets. These splines present the interpolation accuracy compatible with measurement accuracy, i.e., 15–20 mm for spatial displacement determination.

Application of ground laser scanner in surveying and mapping field

With the continuous development of measurement demand, the market of single point measurement mode is shrinking, 3D measurement is more and more appearing in the field of surveying and mapping, ground laser scanner as a portable 3D measurement tool, its use is more and more important. This paper takes substation measurement, cadastral measurement, facade measurement and oil tank measurement as typical cases, and introduces the case of oil tank measurement in detail.

Application of Terrestrial Laser Scanning to Determine Deformations - Practical Aspects

When using laser scanning for deformation analysis of a given object, there are no pre-signalled points or identical points to compare between two epochs, so we can judge for whether an object deforms only by modelling the surface of the object. There are a number of challenges in this regard presented in the paper. The first challenge is that for the deformation analysis the configuration of the measurement parameters is no longer set by the surveyor-engineer by the number and position of the observed points, but from the laser scanner. Only the location of the scanner and the scanning density could be controlled. The second challenge is to expand the error model, as the surface modelling is included in the deformation process. This unifies both the metrological and the model errors that arise from the insufficient knowledge of the object and the simplification of its surface. All these challenges are oriented to the created 3D surface model. In addition, the metrological aspects of the use of laser scanners should be considered, especially for applications where the determination of the deformation requires high accuracy. A number of conclusions and recommendations are formulated. The influence of the factors influencing the accuracy of ground laser scanning in the deformation study is summarised, and the influence of the external orientation ang georefering of the point cloud on the accuracy of the digital model is established. Preliminary assessment of the accuracy of the TLS results are given. Justification of the reliability of the determined deformations through TLS is presented. Technological scheme and recommendations for determination of deformations with TLS is shown.

Detection and Measurement of Cracks in Rock Massifs by Means of Ground Laser Scanning

The analysis of the cracking of the rock massifs is an important stage in the process of their characterization, as this largely determines their mechanical behavior. This is the main reason the mining engineers, who are angaged with the analysis of rock massifs, to require a most detailed and reliable study of the cracks that have arisen in them. Metric characteristics, such as the direction and angle of collapse of the cracks, roughness and average distances between the individual cracks, are extremely important for the study of the structural disturbance of the massif. In the process of the metrics forming of these characteristics, a few of methods of measurement and graphical representation, different in nature and technological features, have become necessary. Through these traditional methods, it is very often not possible to obtain adequate quantitative data for the complete geomechanical characteristics of the rock mass and for the analysis of the mechanisms for its instability. Here, the effectiveness of the ground laser scanning in the study of the structural disturbance (direction and angle of decay of the cracks) and the area cracking coefficient of the rock mass has been experimentally proved. Through this technology the research of the structural disturbance of the rock massifs acquires new quantitative and qualitative dimensions. On the basis of an extremely detailed 3D model, even of hard-to-reach sections of the rock massif, a realistic clustering of cracks and prerequisites for adequate determination of the area cracking coefficient of the massif are created. Moreover, ground-based laser scanning data are an indisputable source of valuable information about rock surface roughness. For an object of the experiment, was selected part of a rock massif, which has well-developed, clearly visible cracks. The scan was performed, using a ground-based laser scanner “Scan Station 2” of the company “Leica”.