Geodetic Control Network Research Articles

Assessment of Passive Geodetic Control Network in Anambra State, Nigeria

Anambra State is facing a number of environmental challenges that require geodetic infrastructure for effective solutions. Unfortunately, much remains to be done in this area as many control stations have been removed from their original locations, leaving some of their pillars in disrepair. To address this issue, a study was conducted to assess the reliability of the geodetic control network in Anambra for various applications. The study involved identifying the location of control stations within the state, assessing the status of the geodetic control network, and confirming the status of individual control stations. Using a handheld GNSS receiver, the control stations were located and critically assessed for their physical condition. In addition, in situ checks were carried out to determine if they were still maintaining their original positions. The results of the study showed that 36% of the visited and located control stations are still intact in their original positions, while 56% have been removed and 8% require maintenance. There should be continuous sensitization of the public on the importance of geodetic controls and the dangers of their destruction.

Influence of reference stations on the stability of the geodetic control network during deformation determination in the area of Kadzielnia in Kielce

Abstract Observations of land surface deformation are one of the important tasks of surveying, especially in landslide areas. They concern the determination in time of the magnitude of the deformation, on the basis of a stable reference system based on a geodetic control points. The whole measurement process can be divided into two parts. One part concerns the observation of reference points (geodetic control points) and the other the observation of the object itself. In the first, in addition to classical methods, GNSS (Global Navigation Satellite System) techniques based on reference stations are used. In the second, common observation methods such as laser scanning or photogrammetric methods using Unmanned Aerial Vehicles (UAV) are used. These observations are carried out in a specific time period in relation to the aforementioned geodetic control points. An area such as Kadzielnia in Kielce is covered by a long-term observation programme. A key element is the survey of the constancy of the geodetic control points, which are located in the epicentre of the survey. The survey of the constancy of the control points at Kadzielnia was based on a static method using SmartNet stations. Taking into account the fact that reference stations are treated as error-free reference points and that they operate 24 hours a day, it was decided to study the variability of their position over a longer period of time, as well as to determine the influence on the geodetic control points and to observe the deformation of the object during the measurement cycles.

The actual state of the geodetic and cartographic resources and legislation in Poland

Abstract Official data, including national geodetic and cartographic resources, are integrated in a spatial reference system. This study outlines national resources in Poland as an important part of the spatial information infrastructure in the European Community. They also provide reference data, including: geodetic control networks, base map, and topographic maps, for other resources of spatial data infrastructure. The study presents changes in the methods of sharing geo-data and technical standards for their collecting in the last few years, and additionally also presents some aspects of progressing geodetic and cartographic resources and legislation in Poland. It was noted that modern national geoportal or regional and district resources and progress, especially in the form of their standardization of presentation, enable to promote the use of spatial data in Poland and their popularization among the international community.

Positioning performance with dual-frequency low-cost GNSS receivers

Abstract In this study, positioning quality is tested with the use of low-cost in-house developed receivers. The analyzes consider the practical use of low-cost devices in surveying works. In the network solution, the accuracy of the GNSS positioning based on low-cost receivers can be characterized by the repeatability of the baseline length of 1 and 6 mm in 24 h and 10 min observation sessions, respectively. The field experiment of 4 GNSS receivers and 3 GNSS low-cost receivers allowed for establishing a precise geodetic control network. The accuracy of the control point coordinates determined with low-cost GNSS receivers equals a maximum of 17 and 40 mm for the horizontal and height components, respectively. Therefore, low-cost GNSS receivers can provide positioning accuracy at the some centimeter level and can support land surveying and geodetic monitoring activities.

CRBeDaSet: A Benchmark Dataset for High Accuracy Close Range 3D Object Reconstruction

This paper presents the CRBeDaSet—a new benchmark dataset designed for evaluating close range, image-based 3D modeling and reconstruction techniques, and the first empirical experiences of its use. The test object is a medium-sized building. Diverse textures characterize the surface of elevations. The dataset contains: the geodetic spatial control network (12 stabilized ground points determined using iterative multi-observation parametric adjustment) and the photogrammetric network (32 artificial signalized and 18 defined natural control points), measured using Leica TS30 total station and 36 terrestrial, mainly convergent photos, acquired from elevated camera standpoints with non-metric digital single-lens reflex Nikon D5100 camera (ground sample distance approx. 3 mm), the complex results of the bundle block adjustment with simultaneous camera calibration performed in the Pictran software package, and the colored point clouds (ca. 250 million points) from terrestrial laser scanning acquired using the Leica ScanStation C10 and post-processed in the Leica Cyclone™ SCAN software (ver. 2022.1.1) which were denoized, filtered, and classified using LoD3 standard (ca. 62 million points). The existing datasets and benchmarks were also described and evaluated in the paper. The proposed photogrammetric dataset was experimentally tested in the open-source application GRAPHOS and the commercial suites ContextCapture, Metashape, PhotoScan, Pix4Dmapper, and RealityCapture. As the first experience in its evaluation, the difficulties and errors that occurred in the software used during dataset digital processing were shown and discussed. The proposed CRBeDaSet benchmark dataset allows obtaining high accuracy (“mm” range) of the photogrammetric 3D object reconstruction in close range, based on a multi-image view uncalibrated imagery, dense image matching techniques, and generated dense point clouds.

Metrica – An application for collecting and navigating to geodetic control network points. Part II: Practical verification

Abstract To prepare the mobile application for the ongoing update of the control network, it is necessary to define detailed procedures for dealing with the points database. These procedures concern the determination of the methodology of making an inventory of the existing database and then the determination of the rules for updating the control network using the developed application. This part describes a practical verification of Metrica for collecting control points data and showing specific cases in the collection and sharing of such data. There were created field inspections using nine different criteria on the set of selected points. Analysis shows that a large part of the points need to be reviewed once again, and its description needs to be updated.

Геодезическое обеспечение выверки формы отражающей поверхности главного зеркала радиотелескопа с применением лазерных трекеров

The article discusses the possibilities of coordinate-determining technology using high-precision geodetic instruments for alignment of reflecting surface shape of the radio telescope main mirror. It’s important for adjustment of reflecting surface shape and consequently performance of radio astronomy observations. The article provides general information about radio telescopes and consideres the existing classical geodesic and non-geodesic methods used in the process of solving the problem of shape alignment. The text describes the method of geodetic work on the form alignment using high-precision laser trackers. The methodology includes several stages from designing the geodetic control network and tracker location stations and processing and interpreting the measurement results. The conditions for performing high-precision measurements are given in the thesis. Mathematical processing of measurement results is performed in the Spatial Analyzer and based on coordinate systems transformation.

Metrica – an application for collecting and navigating geodetic control network points. Part I: Motivation, assumptions, and issues

Abstract The result of surveys largely depends on the accuracy and measurement technique of the control network. This research work presents the application Metrica, dedicated for collection and navigation of geodetic control network points. The main goal of this study is to present the motivation, methodology, and issues with analysis of the database of vertical control points. Such analysis covers south part of Poland territory for the update of the existing set of points of the vertical control network on an ongoing basis. The application has been developed with the use of a test database of points. The status of the points was checked by means of a multi-stage analysis. The prepared database of points was verified taking into account the criteria defined by the authors. In order to optimise the scoring analysis process, two groups of criteria were distinguished: independent of each other and those whose analysis was justified only under the condition of prior verification of other criteria. Based on the analysis of the collected data, the main conclusion was the ongoing need to update the data on the matrix points. It was found that information on points is often incomplete and inaccurate, especially in terms of their horizontal position, which often prevents efficient localisation of points. One of the most significant findings was that only 55.6% of the points available in the database were identified in the field. It should be noted that despite the analysis of the state of the matrix carried out in 2019 on behalf of the GUGiK, there are still many points about which information is not fully up-to-date. It is now possible to extend the application with new attributes and validation rules and conduct updates for several types of geodetic networks. Due to the extensive character of the discussed subject, the study has been divided into two parts. The continuation of this study is the second research work, which presents the development of a mobile application for the update of the geodetic control network. It will present in detail the procedures and IT application development processes.

The Review and Development of the Nigerian Geodetic Control Network

The Nigeria Geodetic Networks were established using primarily triangulation, traversing, trilateration, doppler and levelling networks for numerous control requirements in both surveying and national spatial reference networks. These networks have a number of inherent negative failings that affect its reliability of usage. Various investigations have identified many weaknesses in the network, starting with the origin and other subsequent observational and adjustment defects. Thus, the need to obtain accurate and consistent sets of coordinates with the available space technology and equipment to update and strengthen the network has now become necessary. This work reviews the status of the existing Nigeria Geodetic Networks, and possible ways to improve them are highlighted. The work further proposes a strategy to obtain the most accurate and consistent set of coordinates to serve Geodesy and Geodynamics research, spatial referencing and other mapping activities in the country. The proposed programme of action for improving these networks includes: re-observing the existing network, new set of computations and adjustment of the entire network of controls, and the selection of a suitably chosen system to meet the present and future geodetic needs of positioning.

Establishment of a suitable reference system for the geodetic horizontal control network in hydroelectric construction in Viet Nam

Purpose. To propose an approach that can be applied efficiently when selecting the coordinate system used in hydroelectric construction in Viet Nam. Methodology. The efficiency of the proposed approach is first demonstrated by comparing the relative reduction of distances between the Gauss-Krger and 3-degree and 6-degree UTM projections. It is then proved with an experiment at a hydroelectric power in Viet Nam by comparing the reductions of distances estimated by the proposed approach and those computed from using the VN-2000 coordinate system that is frequently applied. Findings. The experimental results indicated that the proposed approach is more efficient in establishing the geodetic horizontal network in hydroelectric construction in Viet Nam with much smaller distortion in the geometrical size and shape of the network. Originality. This work is the first study on selection of the geodetic horizontal network in hydroelectric construction in Viet Nam based on the average height and the longitude of the center of the construction area. Practical value. The approach proposed in this work can be applied easily and efficiently in practical applications of hydroelectric power construction in Viet Nam, particularly in the areas with high altitude with reference to the ellipsoid as well as the areas located far away from the central meridians of the Viet Nams VN-2000 reference system.

МЕТОДИКА ПРОЕКТИРОВАНИЯ И ПОСТРОЕНИЯ ГЕОДЕЗИЧЕСКОЙ СЕТИ ПРИ НАЗЕМНОМ ЛАЗЕРНОМ СКАНИРОВАНИИ КРУПНЫХ ПРОМЫШЛЕННЫХ ОБЪЕКТОВ

When performing terrestrial laser scanning of large industrial facilities, it must give special atten-tion to designing and establishing a geodetic network to datum transformation measurements into a coordinate system. However, the design of geodetic networks by traditional geodesy methods does not consider all the features of the technique of terrestrial laser scanning. Also worth taking into account is the specifics of laser scanning data processing. Therefore, it is necessary to develop a methodology for designing and establishing a geodetic network in the context of terrestrial laser scanning. For this, the article analyzes the features of terrestrial laser scanning of large industrial facilities and methods for measurement results processing. Based on the analysis and practical experience, developing a flow chart for establishing a geodetic network was on the condition that registration of point cloud perform-ing used iterative closest points algorithm and datum transformation coordinate system performing us-ing HDS targets. Also, based on practical experience, the dependence of the values of the root-mean-square error of registration point cloud and the root-mean-square error of laser scanning station posi-tioning on the distance between the stations. As a result, a methodology for designing and establishing the geodetic network has been substantiated, including two stages. The first stage is the design and ac-curacy assessment of the geodetic control network, the coordinates of which are determined from the datum points by traditional geodesy methods. The second stage is the design and accuracy assessment of the laser scanning station positioning, the coordinates of which are determined from the geodetic control network.

Network-Aided Reduction of Slope Distances in Small-Scale Geodetic Control Networks

AbstractMost of the human-made infrastructures (e.g., dams) need very precise geodetic networks and constant monitoring to detect risks of failure and to plan civil engineering maintenance works. T...

Gauss-Markov model with random parameters to adjust results of surveys of geodetic control networks

Abstract Alignment of an engineering object project in the field is always conducted at the points of the geodetic control network, the coordinates of which are determined on the basis of the results of its elements survey and with connection to the national spatial reference system. The points of the national spatial reference system determined on the basis of previous surveys have specified coordinates with adequate accuracy, which is included in their covariance matrix. The coordinates of the geodetic control network points are determined more accurately than the points of the national spatial reference system and this means that the results of surveys of the geodetic control network have to be adequately incorporated into the coordinates of the reference points. In order to perform this incorporation, it may be assumed that the coordinates of the reference points are random, that is, they have a covariance matrix, which should be used in the process of adjusting the results of the geodetic control network observation. This research paper presents the principles for the estimation of the Gauss-Markov model parameters applied in case of those geodetic control networks in which the coordinates of the reference points have random character. On the basis of the observation equations δ + AX = L for the geodetic control network and using the weighting matrix P and the matrix of conditional covariances (P −1 + AC X A T ) for the observation vector L, the parameter vector X is estimated in the form of the derived formula X ^ = ( C X − 1 + A T PA ) − 1 A T P ⋅ L {\bf{\hat X}} = {\left( {{\bf{C}}_X^{ - 1} + {{\bf{A}}^T}{\bf{PA}}} \right)^{ - 1}}{{\bf{A}}^T}{\bf{P}} \cdot {\bf{L}} . The verification of these estimation principles has been illustrated by the example of a fragment of a levelling geodetic control network consisting of three geodetic control points and two reference points of the national spatial reference system. The novel feature of the proposed solution is the application of covariance matrices of the reference point coordinates to adjust the results of the survey of geodetic control networks and to determine limit standard deviations for the estimated coordinates of geodetic control network points.

Investigation of Vertical Deformation around Trabzon Tide Gauge Station

Nowadays, with the rapid development of technology, the importance of deformation measurement is increasing. Measuring the shape and position changes of natural or artificial structures as a result of external factors are called deformation measurements. In order to determine deformations, geodetic control networks are generally established and measurements are made at various periods in these networks. Deformation analysis is performed using the point coordinates obtained by evaluating the measurements made. GPS is generally used for horizontal and vertical directions and precision levelling method is generally used for vertical direction only in determining deformation in geodetic control networks. Measurements made in different periods are tested with deformation models and it is investigated whether there is deformation in the passing time. In this study, we aimed to examine the vertical crust movements in and around the tide gauge station in Trabzon harbour area. For this purpose, in a leveling network established in the study area, precision levelling measurements were made in two periods, June 2020 (1st period) and October 2020 (2nd period). The measured height differences were adjusted according to the free network method. In both periods, the t-distributed inconsistent test was applied and an inconsistent measure was found for a single route. Adjustment was made by removing the inconsistent measurements found. We investigated whether there has been any movement in the network between two periods by using the θ2-criterion method, one of the static deformation model methods. The vertical movements that may occur between different periods have been determined and we investigated whether there is a vertical deformation around the tide gauge station. The calculations regarding the methods applied within the scope of the study were made using MATLAB program codes written by us. Keywords: Adjustment; Deformation; Precise Levelling; Tide gauge; θ2-Criteria Method

Application of the method of robust estimation by posterior variance in detecting the raw error of geodetic control network

If the raw error appears in set of measuring data, it affects significantly on adjustment results and displacement values of monitoring points, thus conclusion about displacement of works is incorrect. The method of robust estimation by posterior variance for detecting the raw error bases on principle of choosing weight of robust estimation, this is the other type that belong to the least square statistical estimation, which is used to process the measuring data with raw error when they were given into random model of the adjustment problem. Through processing data of Son La hydroelectricity construction network, the obtained result proved that the method good efficiency, it not only finds the measuring value that contains the raw error, but also determines the value of the raw error nearly accurately, moreover, it is able to detect many raw error in the set of data.

Thành lập lưới khống chế trắc địa khu vực trường Đại học Quy Nhơn

Geodetic control network of Quy Nhon University (QNU) is established based on GNSS technology and electronic total station technology in combination with the middle geometrical elevation surveying method, bench mark of network built with firm concrete installed with a centralized insulator cap. The network consists of 11 points, of which 2 points are traversed from the cadastral point of class I, used as the starting points for the traverse. The network is built based on total station method with 2 turns of forward and backward surveying. The network’s leveling height is measured by the middle geometrical elevation surveying method, ensuring compliance with the procedures and rules of the Ministry of Natural Resources and Environment. The research result includes a system of stable and solid network points, together with the coordinates and the leveling height that are closely adjusted by specialized software, control network diagram. Geodetic control network of the QNU is important in setting up map, general plan, planning, construction and serving for teaching and scientific research of the university.

A WEB-BASED GIS PORTAL FOR SIMULATING GEODETIC CONTROL NETWORKS IN REPUBLIC OF KENYA

Geodetic networks development begun in Kenya and Africa as a whole at the dawn of 20th century. Consequently, enormous geodetic data has been realized. In Kenya, the data was recorded in form of paper trigonometric cards, paper topographic maps, and paper cadastral map sheets and centrally archived in the ministry of lands and physical planning headquarters in Nairobi. This was to assist locate and visualize suitable survey of Kenya geodetic pillar of interest to user. However, the user still has to commute to the headquarters in order to physically acquire coordinate information of any pillar in the country. This circumstance has fabricated a framework that has triggered accumulation of millions of paper records. The effectiveness and efficiency of serving the users is greatly undermined by the manual process. Therefore, an alternative solution is necessary to alleviate dependence on an outdated manual process. As a result, this study sought to fill this gap by designing a web geoportal for management of geodetic control networks and user access which incorporates making of payments of coordinates in different systems remotely. The geoportal comprises of an integration of a database management system, a server configuration and a website with an automated data access through a payment gateway. Java scripts and python programming languages were used. The final platform has the following capabilities: spatial visualization, co-ordinates system conversion, online payment, and request and access of data remotely. We foresee that the system will aid the ministry of lands and physical planning to disseminate geodetic information to users efficiently and effectively while tracking revenue payments.

Ground Subsidence Triggered by the Overexploitation of Aquifers Affecting Urban Sites: The Case of Athens Coastal Zone along Faliro Bay (Greece)

Land subsidence in the coastal zone of the Neo Faliro, Moschato, and Kallithea municipalities, along the Faliro bay, has been recorded since the mid 1960’s. This phenomenon has caused damage to buildings, pavements, and roads. Aiming to identify the main causes of the observed ground deformations, data referring to the geological, geotechnical, and hydrogeological settings of the study area has been evaluated. Subsidence has been quantified by the use of space-born Synthetic Aperture Radar interferometry (InSAR) techniques. SVD (Singular Value Decomposition) and IPTA (Interferometric Point Target Analysis) techniques have been applied for the production of deformation maps, referring to the time period between 2002 and 2010. Furthermore, aiming to extend the study of the phenomenon further to the past, Persistent Scatterer Interferometry (PSI) data for the time period from 1992 to 2001 were also evaluated. Finally, the results of the InSAR analysis have been crosschecked with measurements acquired by a vertical geodetic control network as well as by ground truth data, referring to damage inventory of the site. The current research presents an interesting case study of an urban site affected for a long-lasting period by the activities of a neighboring industrial zone. The development of an extensive depression cone, mainly due to the overexploitation of the aquifers for industrial use, is the main cause of the land subsidence phenomenon, without excluding a component of motion due to the natural compaction of the compressible soil in the area of interest. The complexity of the geological, hydrogeological, and geotechnical conditions and the interaction of the numerous land use activities make this study far more interesting.

Increasing efficiency of the robust deformation analysis methods using genetic algorithm and generalised particle swarm optimisation

The paper analyses the possibility of increasing efficiency of the Iterative Weighted Similarity Transformation (IWST) method, which is a prototype of classic robust methods, using global optimisation approach instead of classical one, available in the literature. For the purpose of solving the optimisation problem of the IWST method, in addition to the Iterative Reweighted Least Squares (IRLS) method, the Genetic algorithm (GA) and Generalised Particle Swarm Optimisation (GPSO) algorithm were applied, in order to overcome some flaws of IRLS method. Experimental research was performed based on the Monte Carlo simulation using the mean success rate (MSR) on the example of the geodetic control network for monitoring the Šelevrenac dam in the Republic of Serbia. By using the GA and GPSO algorithms, the overall efficiency of the IWST method has been increased by about 18% compared to the IRLS method. Also, it has been determined that the efficiency of the IRLS method significantly reduces with the increase in the number of displaced potential reference points (PRPs), while the GA and GPSO algorithms’ efficiency does not change significantly. The values of overall absolute true errors due to the increased number of displaced PRPs in the GA and GPSO algorithms did not change notably while with the IRLS method their values increased significantly.

КОНЦЕПТУАЛЬНЫЙ ПОДХОД К ГЕОДЕЗИЧЕСКОМУ ОБЕСПЕЧЕНИЮ 3D-КАДАСТРА

The article considers the approach to 3D cadastre geodetic control creation. Within the framework of this approach it is suggested to present the given production process by two technological operations: creation of geodetic control network in cadastral block to coordinate the external contour of capital construction object (CCO) and 3D modeling of its internal elements (premises). To implement these technological procedures, a regulatory framework for performing geodetic measurements and a coordinate system for entering the necessary information in the unified state register of real estate (USRRE) and performing 3D modeling of the structural elements of the CCO is proposed. It is noted that when implementing the proposed technological solutions, the technical plan prepared by the cadastral engineer can be considered not only as a document that allows the state cadastral registration of the ACS and its structural elements, but also as a regulatory document that determines the compliance of the erected building with its design parameters.