Geodetic Coordinate System Research Articles

Mine seismic source location via forward modeling of spherical waves in a multilayered horizontal or inclined medium

Seismic source location is a classic inverse problem in seismology. In mathematical physics, inverse problems have multiple natural solutions. The objective of this study was to develop a generic theory and method of seeking the true solution from multiple solutions for the location of a coal mine seismic source in an idealized velocity structure model of a coal mine with a small scale and complex geological environment. Starting from the simplest velocity structure model, the complexity of the model gradually increased, until it approached the real velocity structure model, i.e., the multilayered horizontal and inclined velocity structure model, in order to find a generic method for solving the multi-solution inverse problem of coal mine seismic source location. Specifically, the wavefront distribution equation in a two-layer horizontal medium was derived and then expanded to any multi-layer horizontal medium. Based on this equation, a positive definite nonlinear equation system was established from the perspective of any observation system. The equation system contained four unknown variables of the spatiotemporal position of the seismic source. To determine the spatiotemporal parameters of the seismic source, nonlinear equations for four stations were required. To solve the nonlinear equation system, an initial iteration value was determined. In order to reduce the difficulty of determining the initial iteration value, the variable substitution method was used to reduce the number of location parameters. By rotating the original geodetic coordinate system of the station to be parallel and orthogonal to the medium interface, the wavefront method was extended to inclined medium. In conclusion, in this study, the problem of coal mine seismic source location in a multi-layer horizontal or inclined medium was effectively solved. The method proposed in this study provides a reference for solving the true solution from multiple solutions for the location of a coal mine seismic source in small-scale coal mines with complex geological environments.

Transformation of initial cartographic materials for the “Main State Topographic Map” to coordinate system UCS-2000

Abstract Initial cartographic materials were determined to create the topographic database of the “Main State Topographic Map”. They require preparation for creating (updating) digital topographic maps at the scale of 1:50,000. One of the stages of preparation of input cartographic materials is their transformation to the coordinate reference system UCS-2000. The goal of the article is to research the problem of transformation of points coordinates by the rigorous mathematical method for referencing cartographic materials from the coordinate systems CS-42/CS-63 to the State Geodetic Coordinate Reference System UCS-2000 (after this – UCS-2000) by geographic information systems (GIS) for creation (updating) digital topographic maps at the scale of 1:50,000 to create the seamless topographic database of the “Main State Topographic Map” on the territory of Ukraine. Authors propose a method of transformation orthophoto at the scale of 1:10,000 to UCS-2000 in Cartesian coordinates of Gauss-Krüger projection in the corresponding 6-degree zone in the adopted state interchart of topographic maps at the scale of 1:50,000. This method consists of cartographic materials transformation using a transformation field in the form of a GRID model based on the triangulation TIN model using the finite element method. The choice of the finite element method and the peculiarities of affine transformation are mathematically substantiated. Also, the authors determined the requirements for the method of coordinates transformation.

Алгоритм траекторной фильтрации источников радиоизлучения в многопозиционных пассивных радиолокационных системах с дополнительным наблюдением высоты полета

This work is devoted to developing an algorithm for trajectory filtering in multi-position passive radar systems. This paper presents an algorithm that uses the flight altitude in the geodetic coordinate system as an additional observation. In practice, this information can be known if the radio radiation source uses an onboard IFF responder in A/C mode. In this case, the flight altitude can be decoded and used as an additional observation. In this paper, a simulation was performed to compare the effectiveness of the proposed algorithm with the standard one based on the Extended Kalman filter without using additional observation. Comparison of the algorithms was also carried out on experimental data. It is shown that the use of a priori information about the geode¬tic altitude of the flight as additional observations of the algorithm allows not only to increase the accuracy of two-dimensional coordinate estimation (up to 2.5 times), but also to increase the stability of trajectory tracking in comparison with the algorithm that does not take this information into account.

Fast Solution of Scattering and Micro-Doppler Features from Moving Target Using a Tailored Shooting and Bouncing Ray Method

In this paper, we present a tailored shooting and bouncing ray (SBR) method for the fast solution of electromagnetic (EM) scattering from a moving target. And, the micro-Doppler features of the moving target are investigated using a time-frequency analysis technique. In our method, a dynamic spatial division technique is employed to accelerate facet information processing and ray-tracing progress of the moving target. At first, the two coordinate systems are established, which are the geodetic coordinate system (GCS) and the local coordinate system (LCS). In GCS, the target is moving with translation and rotation. The dynamic spatial division is established in LCS to store the facet information and remain relatively stationary to the target. In comparison with the traditional SBR method, this technique avoids repetitive spatial division at each moment in the GCS. Then, ray tracing is performed to find the illuminated facets in the LCS. Finally, the scattering field and the phase compensation are computed in the GCS. In numerical simulations, the verification and computation efficiency comparison are provided using our method and other solutions (MLFMM, RL-GO, and traditional SBR). Moreover, the micro-Doppler features are extracted and analyzed using the time-frequency analysis technique, which includes the precession and spin of the missile, and the rotation of the aircraft. Meanwhile, the micro-Doppler spectra of the target is also compared with the theoretical Doppler of equivalent strong scattering points, which are obtained using the instantaneous high-resolution range profile (HRRP).

Multisensor and Multiscale Data Integration Method of TLS and GPR for Three-Dimensional Detailed Virtual Reconstruction.

Integrated TLS and GPR data can provide multisensor and multiscale spatial data for the comprehensive identification and analysis of surficial and subsurface information, but a reliable systematic methodology associated with data integration of TLS and GPR is still scarce. The aim of this research is to develop a methodology for the data integration of TLS and GPR for detailed, three-dimensional (3D) virtual reconstruction. GPR data and high-precision geographical coordinates at the centimeter level were simultaneously gathered using the GPR system and the Global Navigation Satellite System (GNSS) signal receiver. A time synchronization algorithm was proposed to combine each trace of the GPR data with its position information. In view of the improved propagation model of electromagnetic waves, the GPR data were transformed into dense point clouds in the geodetic coordinate system. Finally, the TLS-based and GPR-derived point clouds were merged into a single point cloud dataset using coordinate transformation. In addition, TLS and GPR (250 MHz and 500 MHz antenna) surveys were conducted in the Litang fault to assess the feasibility and overall accuracy of the proposed methodology. The 3D realistic surface and subsurface geometry of the fault scarp were displayed using the integration data of TLS and GPR. A total of 40 common points between the TLS-based and GPR-derived point clouds were implemented to assess the data fusion accuracy. The difference values in the x and y directions were relatively stable within 2 cm, while the difference values in the z direction had an abrupt fluctuation and the maximum values could be up to 5 cm. The standard deviations (STD) of the common points between the TLS-based and GPR-derived point clouds were 0.9 cm, 0.8 cm, and 2.9 cm. Based on the difference values and the STD in the x, y, and z directions, the field experimental results demonstrate that the GPR-derived point clouds exhibit good consistency with the TLS-based point clouds. Furthermore, this study offers a good future prospect for the integration method of TLS and GPR for comprehensive interpretation and analysis of the surficial and subsurface information in many fields, such as archaeology, urban infrastructure detection, geological investigation, and other fields.

INDOOR POSITIONING AND NAVIGATION BASED ON QR CODE MAP

Abstract. Solving the indoor positioning problem can effectively improve work and life efficiency. Outdoors, navigation and positioning mainly rely on satellites to provide global positioning and road network topology to constrain the direction of travel. Therefore, to achieve good indoor navigation and positioning, two things are needed: 1) continuous position acquisition and 2) an indoor road network. Since the indoor environment is relatively stable, the geodetic coordinates of key indoor nodes can be obtained in advance through measurement methods and control points can be set up. Inertial navigation is stable and autonomous, and when combined with control points, it can achieve stable position acquisition. QR codes are rich in information, low in cost, and easy to deploy. They can be used as nodes to construct an indoor road network or as control points. This study proposes an indoor road network map construction method that can achieve local accuracy and global consistency in large indoor scenes. In this indoor road network map, node information includes the position and posture of the QR code. When a machine passes through a node position, it can obtain its absolute position and direction in the geodetic coordinate system by taking a picture of the node’s QR code and combining it with IMU fusion positioning. Through map edge information, indoor navigation and path planning can be achieved.

Borehole TV Imaging Technology for Horizontal Directional Drilling Based on an Optimization Algorithm for Structural Planes

The horizontal directional drilling technology combined with the borehole TV imaging technology can be used to obtain most of the geological information in conventional adit exploration. This combination has little impact on the environment and is free from topographic constraints, thus contributing to green exploration. However, conventional algorithms for structural planes fail to accurately extract information on the attitudes of incomplete structural planes in boreholes of any azimuth. Moreover, existing borehole TV devices are mostly cable-based and, thus, difficult to put in place in horizontal drilling. They are prone to get stuck in the collapse section of boreholes, thus damaging the devices. Given these challenges, this study develops an optimization algorithm for structural planes: (1) first, information on multiple points in the 2D unfolded view is fitted using a sinusoidal function curve, three arbitrary points are constructed using the fitted curve, and the normal vector of the plane determined by the three points is calculated; (2) the normal vector in the geodetic coordinate system is obtained after two rotations of the spatial coordinate system based on the theory of transformation of Cartesian coordinate system; (3) finally, the dip angle and dip direction of a structural plane are calculated using the normal vector in the geodetic coordinate system. By making the best use of the information on multiple points in the 2D unfolded view, the optimization algorithm can overcome the defect that is difficult for conventional two-point methods to locate the highest and lowest points of discontinuous structural planes. Therefore, the optimization algorithm applies to calculating the attitudes of structural planes in boreholes of any azimuth. Based on this optimization algorithm, this study successfully develops a cable-free, storage-based TV device for boreholes of any azimuth. This device was employed for laboratory experiments on 20 complete structural planes and 32 incomplete structural planes. As indicated by the experiment results, the optimization algorithm proposed in this study is applicable to many types of structural planes, with a dip direction error of less than 10° and a dip angle error of less than 5°, thus meeting the production requirements.

IMPROVING THE USE OF GEODETIC, GEOCENTRIC, AND TOPOCENTRIC COORDINATE SYSTEMS IN METEOR ASTRONOMY AND RELATED TASKS

The problem of using the geodetic, geocentric, and topocentric coordinate systems in video observations’ processing of meteors and other dynamical objects in Earth’s atmosphere is considered. For meteor heights in a range of 0…200 km and arbitrary Earth’s ellipsoid latitudes, the following values are calculated: the difference between geodetic and geocentric latitudes, the meridian arc length corresponding to this shift, and the difference between geocentric and geodetic altitudes above the Earth’s ellipsoid. The carried-out calculations allowed us to conclude that the geocentric coordinate system is optimal for the calcula- tion of kinematic parameters of meteors and trajectory measurements of ballistic objects at all-range altitudes and long distances between observation points without using horizontal coordinate systems as intermediate ones. This coordinate system is also used in the computation of heliocentric orbit elements of meteoroids. It is noted that the transition from the geocentric to the geodetic coordinate system is necessary for mapping the projections of the meteor trajectory to search for their remnants — meteorites. The reason is related to the difference between them, which can reach 11 arcmin for objects located at an altitude of 100 km above the level of the Earth’s ellipsoid, which corresponds to the shift of 21 km. The difference between geocentric and geodetic altitudes is inessential and amounts to half a meter at an altitude of 100 km and slightly more than one meter at 200 km and can be neglected in meteor calculations and most ballistic tasks. These considerations formed the basis for our proposed alternative vector method for the inverse transition from geocentric to geodetic coordinates and the numerical solution of the corresponding equation. In order to decrease the calculation time for mass processing, it is recommended to change the numerical processing of the inverse task by fitting it with elementary functions. An example of fitting is given. It brings to the maximal deviation in latitude near one arcmin, which corresponds to approximately 35 meters. It is noted that such precision is satisfactory for meteor measurements, but for ballistic problems, the accuracy of fitting must be improved.

Improving maritime traffic surveillance in inland waterways using the robust fusion of AIS and visual data

To guarantee vessel traffic safety in inland waterways, the automatic identification system (AIS) and shore-based cameras have been widely adopted to monitor moving vessels. The AIS data could provide the unique maritime mobile service identity (MMSI), position coordinates (i.e., latitude and longitude), course over ground, and speed over ground for the vessels of interest. In contrast, the cameras could directly display the visual appearance of vessels but fail to accurately grasp the vessels’ identity information and motion parameters. In this paper, we propose to improve the maritime traffic surveillance in inland waterways using the robust fusion of AIS and visual data. It is able to obtain more accurate vessel tracking results and kinematic characteristics. In particular, to robustly track the visual vessels under complex scenarios, we first propose an anti-occlusion vessel tracking method based on the simple online and real-time tracking with a deep association metric (DeepSORT) method. We then preprocess and predict the vessel positions to obtain synchronous AIS and visual data. Before the implementation of AIS and visual data fusion, the AIS position coordinates in the geodetic coordinate system will be projected into the image coordinate system via the coordinate transformation. A multi-feature similarity measurement-based Hungarian algorithm is finally proposed to robustly and accurately fuse the AIS and visual data in the image coordinate system. For the sake of repeating fusion experiments, we have also presented a new multi-sensor dataset containing AIS data and shore-based camera imagery. The quantitative and qualitative experiments show that our fusion method is capable of improving the maritime traffic surveillance in inland waterways. It can overcome the vessel occlusion problem and fully utilizes the advantages of multi-source data to promote the maritime surveillance, resulting in enhanced vessel traffic safety and efficiency. In this work, the presented multi-sensor dataset and source code are available at https://github.com/QuJX/AIS-Visual-Fusion.

A Method for Calculating the Band Change of Gauss Projection Coordinates

In geodesy, many surveying projects are carried out on the plane, which requires the transformation of geodetic coordinates, the element on the ellipsoid, into plane coordinates, and each independent coordinate system has new contradictions due to zoning. Based on the basic geometric parameters and the mathematical description of the earth ellipsoid, this paper introduces the principle of Gauss projection method. Since Gauss Krueger projection is currently used in China, this paper introduces the principle and method of Gauss projection, and deduces the correlation between the Gauss plane coordinates (x, y) and the geodetic coordinates (L, (B)), that is, the forward and reverse calculation formulas of Gauss projection. With the help of Gauss projection as a communication "bridge", the coordinate transformation calculation is studied from geodetic coordinate transformation, and its advantages and disadvantages are compared with other methods. Based on the 1954 Beijing coordinate system and 1980 Xi'an coordinate system commonly used in China, a geodetic coordinate conversion system is compiled using C # language, and the forward and inverse calculation of Gaussian projection is realized.

Accuracy comparison of rock discontinuity geometric parameters in photogrammetry based on two georeferencing methods: Control points and geotagged photos

During the reconstruction of the digital outcrop models (DOM) by photogrammetry, the geodetic coordinate systems of the models can be calibrated through the camera positions or the control points. This paper developed a procedure for constructing virtual digital outcrop model (VDOM) and proposed a numerical simulation procedure of photogrammetry to compare the measurement accuracy of the mentioned-above two methods. A physical model test indicated the validation of the proposed procedure. In addition, many numerical experiments about the accuracy of the camera positions and the control points are designed. The experiment results show that when the control points are used to georeference the DOMs, it is recommended to measure the coordinates of the control points by the device with high positioning accuracy, such as the total station or RTK equipment. If the device with high positioning accuracy is unavailable, better measurement accuracy can be obtained using the camera positions.

A Novel All-Weather Method to Determine Deflection of the Vertical by Combining 3D Laser Tracking Free-Fall and Multi-GNSS Baselines

The bright stars in the clear night sky with weak background lights should be observed in the traditional deflection of the vertical (DOV) measurement so that the DOV cannot be observed under all-weather conditions, which limits its wide applications. An all-weather DOV measurement method combining three-dimensional (3D) laser tracking free-fall and multi-GNSS baselines is proposed in this paper. In a vacuum environment, the 3D laser tracking technique is used to continuously track and observe the motion of free-fall with high frequency and precision for obtaining 3D coordinate series. The plumb line vector equation is established to solve the gravity direction vector in the coordinate system of the laser tracker at the measuring point using least squares fitting coordinate series. Multi-GNSS observations are solved for obtaining the precise geodetic cartesian coordinates of the measuring point and GNSS baseline information. A direction transformation method based on the baseline information proposed in this paper is used to convert the gravitational direction vector in the laser tracker coordinate system into the geodetic cartesian coordinate system. The geodetic cartesian coordinates of the measuring point are used to calculate the ellipsoid normal vector, and the angle between this and the gravity direction vector in the geodetic cartesian coordinate system is estimated to obtain the astrogeodetic DOV. The DOV is projected to the meridian and prime vertical planes to obtain the meridian and prime vertical components of the DOV, respectively. The astronomical latitude and longitude of the measuring point are calculated from these two components. The simulation experiments were carried out using the proposed method, and it was found that the theoretical precision of the DOV measured by the method could reach 0.2″, which could realise all-weather observation.

FEATURES OF CREATION AND RESTORATION OF SUPPORTING GEODESIC NETWORK IN ROAD CONSTRUCTION MEASUREMENTS

The success of the implementation of projects of capital repairs, reconstruction or new construction of roads and man-made structures depends on the quality of geodetic support. Geodetic marking works must accompany the process of construction or repair work. Particular attention should be paid to the peculiarities of the creation and restoration of the geodetic support network in road construction, as these issues have a primary impact on the success of development and implementation of repair and construction projects and therefore affect the entire life cycle of the highway. The laying of points of the geodetic reference network is performed in order to ensure topographic survey at the stage of surveys and to ensure further marking works at the stage of overhaul, reconstruction or new construction of the highway. The project of creating a geodetic reference network must be included in the main work program or compiled separately and agreed with the customer. The project of creating a geodetic reference network must display information on the type of network points, density and location of points, methods of geodetic measurements, coordinate systems and heights, basic requirements for the accuracy of the position of geodetic reference points and requirements for reporting materials in the technical report. The location, type of fastening, construction and external design of the points of the basic geodetic network must ensure the preservation of the spatial position, protection from damage and loss of points. Metal structures of geodetic signs and design elements must be protected from corrosion by a special anti-corrosion coating. The location of the points is determined after the reconnaissance work, study of the initial data and the needs of design, construction and operation. The proposed features of creation and restoration of the basic geodetic network in road construction are reflected in DSTU 9154:2021 «Guidance on performance of geodesic works in road building».

Tuz Mağaralarında Sırt Çantası LiDAR Sisteminin 3B Model Üretiminde Kullanılması; Tuzluca, Iğdır Örneği

Caves have an important place in world history. In addition to the protective and flavoring properties of salt, the conclusion that it can be an alternative treatment for various diseases has increased the importance of salt caves. In this study, a 3D model of the salt cave located in the Tuzluca District of Iğdır Province, which was opened for the purpose of health tourism, was created using the backpack LiDAR system. The fact that the backpack LiDAR system is supported by a fast, flexible use and SLAM algorithm has increased its use in confined spaces such as caves. The created model has been converted into a geodetic coordinate system. It is observed that the location and transformation accuracy of the model are within the usable accuracy in geodetic studies. With this study, it was determined that the backpack LiDAR system can be used in cave studies.

Data-driven online traffic reconstructions: Interactively optimizing in virtual reality

It is important to realize three-dimensional (3D) online traffic reconstructions based on the video data. Existing methods always use structured data to generate 3D traffic reconstructions and do not process unstructured pixel data. In this paper, we propose a 3D online traffic reconstruction method driven by video data and virtual traffic simulations. There are mainly two steps in our method. The first step is data preprocessing. We extract vehicles’ trajectories from video data and transform them into the geodetic coordinate system. The transformation parameters are optimally solved in multiple human–computer interactions. The second step is trajectory reconstructions. We use the traffic simulation method to predict vehicles’ trajectories and use the Kalman filter to optimize vehicles’ trajectories according to the extracted trajectories and the predicted trajectories. We also optimize the traffic simulation parameters iteratively according to the optimized trajectories when needed. The experimental results show that our method can provide realistic and smooth traffic reconstructions. It has nearly the same efficiency as that of existing online multiple object tracking methods.

О СОХРАНЕНИИ ФОНДОВ ПРОСТРАНСТВЕННЫХ ДАННЫХ, СОЗДАННЫХ В СК-95, ПРИ ПЕРЕХОДЕ К ГСК-2011

The article gives an assessment of the measures taken in the constituent entities of the Russian Federation for the transition from CS-42 to CS-95 as one of the stages in preparation for the introduc-tion of a new state geodetic coordinate system SCS-2011. It is noted, that those subjects of the Russian Federation, where the work on the transition in the creation of spatial data necessary for the socio-economic development of the regions, from a variety of local coordinate systems (LCS) based on CS-42, to a single local coordinate system of the region, created on the basis of CS-95, has already been implemented, have advantages in the transition to SCS-2011. Such regions have the opportunity to move to SCS-2011 by establishing a connection between the unified local coordinate system of the region, based on CS-95, and SCS-2011 in the form of unified regional parameters of the orthogonal transformation.The problem of preserving the spatial data funds created in CS-95 during the transition to SCS-2011 is also considered. It is noted that for the participants of the geospatial market, law-abiding and timely (after the abolition of CS-42 and the introduction of CS-95) who converted their geodetic materials and data from CS-42 to CS-95, the problem of their preserva-tion during transition to SCS-2011 without the need for recalculation in SCS-2011. As a solution to this problem, the author proposed a new type of local coordinate system based on SCS-2011.

Updating of digital topographic maps in the new national spatial coordinate system: case Fergana valley in Uzbekistan

Abstract. The classical geodetic coordinate system (CS42) in Uzbekistan uses the Krasovsky ellipsoid. The implementation of new information technologies, such as the Global Navigation Satellite System, became the basis for the development of a new national open geocentric coordinate system. This paper describes the development of a distortion grid for transforming horizontal spatial data from the local geodetic datum CS42 to a geocentric datum WGS84 for 1:100000 scale maps of the Fergana Valley in Uzbekistan. A first version of the distortion grid file has been created for transforming between CS42 and WGS84 for the whole territory of the country. The significant influence of the longitudinal drift of the region has been confirmed. The grid was used to transform topographic maps at a scale of 1:100000 for the Fergana Valley. Changing the map datum has shifted the grid of coordinate systems by 70 m in the East and 7 m in the North.

Uzbekistan's coordinate system transformation from CS42 to WGS84 using distortion grid model

Currently, a non-geocentric geodetic coordinate system introduced in 1942 (CS42), based on the Krasovsky ellipsoid and the Baltic system of normal heights introduced in 1977, is used for geodetic works in the Republic of Uzbekistan. The development of the GNSS network proposes a task of transition to a new geocentric system based on the World Geodetic System 1984 (WGS84) ellipsoid. Many software products adopt 3- or 7-parameter conversions, which can cause errors up to several meters and are not suitable for many applications. In this case, local transformations using a grid of differences between observation points with known coordinates in both datums would give the best accuracy. In this paper, we discuss various interpolation methods (Kriging, Minimum Curvature, Inverse Distance to a Power and Radial Basis Function) to solve the distortion modeling between CS42 and WGS84 systems for national datum improvement. The results show that the distortion models share a common tendency for all interpolation methods: the maximum horizontal displacements are concentrated along the West Tien Shan lineament, which is the boundary of the relief lowering. The discrepancies between the grid-based (calculated) and GPS-measured coordinates are evaluated. Statistical and spatial analysis has confirmed that for the coordinate transformation from CS42 to WGS84 and vice versa, grid-based transformation with Radial Basis Function interpolation has a high accuracy transformation. Analysis of the available data across the eastern part of the country shows that some positional distortions existed between the CS42 and WGS84 datums. For the best RBF method, the magnitude of these distortions is about 0.019–0.755 m with a standard deviation of 0.015 m.

PERFORMANCE OF ENGINEERING SURVEYS AS AN INTEGRAL PART OF LAND AND CADASTRE WORKS IN PREPARATION OF LAND PLOTS FOR REGISTRATION IN THE BASE OF THE STATE LAND CADASTER

Performing engineering surveys is a mandatory part of the development of technical documentation on land management. Surveys allow to confirm the accuracy of the performed geodetic or topographic survey. In particular, the accuracy of determining the geodetic coordinates of the turning points of the boundaries of the land, to link the turning points of the boundaries of the land to the geodetic points of the State Geodetic Network of Ukraine. The main purpose of the article is to reflect the main components of engineering surveys as part of land cadastral works in preparation of land for registration in the database of the State Land Cadastre. The coordinate basis for land management is the State Geodetic Reference Coordinate System USK-2000, the geodetic basis for land management – points of the State Geodetic Network 1-3 classes, points of geodetic networks of compaction 4 class, 1 and 2 categories, points of the surveying network. The coordinates of the points of the State Geodetic Network of Ukraine, geodetic networks of condensing and turning points of the boundaries of geospatial objects are determined by rectangular coordinates (x, y) in the Gauss-Krueger projection in the USC-2000 coordinate system or local coordinate systems. related to the USC-2000 coordinate system. The control of the differential field of coordinate corrections when working with the use of RTK technologies is carried out at least at the two nearest points of DGM and GMZ, the coordinates of which are obtained from the administrator of the geodetic data bank. The difference in the values of the coordinates of control points should not exceed 0.1 m in cities of regional importance, 0.2 m - in other cities and towns, 0.3 m - in rural areas and 0.5 m - outside the settlements. Keywords: engineering surveys, State Geodetic Network of Ukraine, land cadastral works, coordinate system, State Land Cadastre.

Processing Laser Point Cloud in Fully Mechanized Mining Face Based on DGCNN

Point cloud data can accurately and intuitively reflect the spatial relationship between the coal wall and underground fully mechanized mining equipment. However, the indirect method of point cloud feature extraction based on deep neural networks will lose some of the spatial information of the point cloud, while the direct method will lose some of the local information of the point cloud. Therefore, we propose the use of dynamic graph convolution neural network (DGCNN) to extract the geometric features of the sphere in the point cloud of the fully mechanized mining face (FMMF) in order to obtain the position of the sphere (marker) in the point cloud of the FMMF, thus providing a direct basis for the subsequent transformation of the FMMF coordinates to the national geodetic coordinates with the sphere as the intermediate medium. Firstly, we completed the production of a diversity sphere point cloud (training set) and an FMMF point cloud (test set). Secondly, we further improved the DGCNN to enhance the effect of extracting the geometric features of the sphere in the FMMF. Finally, we compared the effect of the improved DGCNN with that of PointNet and PointNet++. The results show the correctness and feasibility of using DGCNN to extract the geometric features of point clouds in the FMMF and provide a new method for the feature extraction of point clouds in the FMMF. At the same time, the results provide a direct early guarantee for analyzing the point cloud data of the FMMF under the national geodetic coordinate system in the future. This can provide an effective basis for the straightening and inclining adjustment of scraper conveyors, and it is of great significance for the transparent, unmanned, and intelligent mining of the FMMF.