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- Vehicle detection and masking in UAV images using YOLO to improve
photogrammetric products
Abstract: Photogrammetric products obtained by processing data acquired with Unmanned Aerial Vehicles (UAVs) are used in many fields. Various structures are analysed, including roads. Many roads located in cities are characterised by heavy traffic. This makes it impossible to avoid the presence of cars in aerial photographs. However, they are not an integral part of the landscape, so their presence in the generated photogrammetric products is unnecessary. The occurrence of cars in the images may also lead to errors such as irregularities in digital elevation models (DEMs) in roadway areas and the blurring effect on orthophotomaps. The research aimed to improve the quality of photogrammetric products obtained with the Structure from Motion algorithm. To fulfil this objective, the Yolo v3 algorithm was used to automatically detect cars in the images. Neural network learning was performed using data from a different flight to ensure that the obtained detector could also be used in independent projects. The photogrammetric process was then carried out in two scenarios: with and without masks. The obtained results show that the automatic masking of cars in images is fast and allows for a significant increase in the quality of photogrammetric products such as DEMs and orthophotomaps.
PubDate: Sat, 24 Dec 2022 00:00:00 GMT
- A crossvalidation-based comparison of kriging and IDW in local
GNSS/levelling quasigeoid modelling
Abstract: This study compares two interpolation methods in the problem of a local GNSS/levelling (quasi) geoid modelling. It uses raw data, no global geopotential model is involved. The methods differ as to the complexity of modelling procedure and theoretical background, they are ordinary kriging/least-squares collocation with constant trend and inverse distance weighting (IDW). The comparison itself was done through leave-one-out and random (Monte Carlo) cross-validation. Ordinary kriging and IDW performance was tested with a local (using limited number of data) and global (using all available data) neighbourhoods using various planar covariance function models in case of kriging and various exponents (power parameter) in case of IDW. For the study area both methods assure an overall accuracy level, measured by mean absolute error, root mean square error and median absolute error, of less than 1 cm. Although the method of IDW is much simpler, a suitably selected parameters (also trend removal) may contribute to differences between methods that are virtually negligible (fraction of a millimetre).
PubDate: Fri, 28 Oct 2022 00:00:00 GMT
- Applicability analysis of attention U-Nets over vanilla variants for
automated ship detection
Abstract: Accurate and efficient detection of ships from aerial images is an intriguing and difficult task of extreme societal importance due to their implication and association with maritime infractions, and other suspicious actions. Having an automated system with the required capabilities indicates a substantial reduction in the related man-hours of characterization and the overall underlying processes. With the advent of various image processing techniques and advancements in the field of machine learning and deep learning, specialized methodologies can be created for the said task. An intuition for the enhancement of existing methodologies would be a study on attention-based cognition and the development of improved neural architectures with the available attention modules. This paper offers a novel study and empirical analysis of the utility of various attention modules with U-Net and other subsidiary architectures as a backbone for the task of computationally efficient and accurate ship detection. The best performing models are depicted and explained thoroughly, while considering their temporal performance.
PubDate: Fri, 28 Oct 2022 00:00:00 GMT
- Possibilities of geoinformational analysis for assessment of the state and
Abstract: Topographic, geodetic and cartographic activities are one of the main activities for the effective development of the economy, science of strengthening national security and defense. It is a set of management, production, scientific and educational activities for the storage and communication to users of geodetic and cartographic information and data. The article considers one of the segments of this activity – the state of geodetic support of the territory of Ukraine and its assessment according to official data on the possibility of creating topographic maps and plans of scale 1:25 000 – 1:2000 in compliance with applicable regulations. To carry out the assessment, around the points of the State Geodetic Network of Ukraine (DGM) buffer zones of radii of circles of standard sizes were constructed, zoning of the territory with Thissen-Voronoi polygons and covering of the territory in the form of a hexagonal grid were done by means of ArcGIS. The results of the current assessment as of 2022 conducted by three methods are summarized in the table in terms of oblasts of Ukraine. The data obtained are compared to the previous assessment conducted five years ago. Changes in the state of geodetic support have been identified and their objective reasons explained. The advantages and disadvantages of each of the proposed methods of geoinformation analysis of the assessment of the state of geodetic support of the territories are given. It is established that the combination of different methods will allow to use the existing points of DGM with greater efficiency and to substantiate the priority places for further development of the network. The complex of scientific and applied works related to the modernization of the state geodetic network will allow to quickly and locally develop a network based on satellite and computer technologies and create and present digital cartographic information at the modern scientific and technical level in accordance with current needs.
PubDate: Tue, 21 Jun 2022 00:00:00 GMT
- Research of the environmental temperature influence on the horizontal
displacements of the Dnieper hydroelectric station dam (according to GNSS
measurements)
Abstract: The paper studies the relationship between the ambient temperature change and the horizontal displacements on control points of the Dnieper Hydroelectric Station dam from 2016 to 2020. A specially developed software product analyzed the GNSS time series of measurements pre-processed by the GeoMoS system to determine the parameters of seasonal displacements and their relationship with seasonal changes in air temperature. The research established that the influence of ambient temperature in the absence of significant changes in the water level in the upper reservoir determines the cyclicity of dam deformations. It is established that the projections of velocity vectors of reference points in the ETRF-2014 system for the studied period do not exceed the absolute value of 3 mm/month. The directions of the horizontal displacement vectors in the first half of each year are opposite to the directions recorded in the second half. In the first half of the year, the dam’s body shifts towards the reservoir, while in the second half year period, it shifts-backwards. According to the three-year GNSS monitoring of the Dnieper Hydroelectric Station dam, the amplitude of semi-annual horizontal oscillations of the control points relative to the dam axis is from -9.5 to +8 mm. In winter and summer, the horizontal displacements increase from the edges of the dam to its central part, and the amplitudes of the horizontal displacements move vice versa. The obtained data establish a linear analytical relationship between the average temperature and the horizontal displacements of the GNSS control points.
PubDate: Mon, 06 Jun 2022 00:00:00 GMT
- Evaluating Repeatability of RTK (GPS and Galileo/GPS) performance in the
analysis of points located in areas with and without obstructions
Abstract: Galileo is Europe’s Global Navigation Satellite System (GNSS), which provides improved positioning and timing data with significant benefits for many European services and users. Galileo enables users to know their exact location with greater precision than other available systems. Access to the Galileo signal in the obstructed and unobstructed environment provides benefits and opportunities for work, thanks to the improved performance and accuracy. The use of a Galileo-enabled receiver increases the number of satellites in view significantly. When compared to the performance of single-constellation receivers, this significantly reduces the time required to obtain a position with centimetre-level accuracy. The results indicate the current Galileo constellation’s suitability for high-precision RTK applications, as well as improved availability, accuracy, reliability, and time-to-fix in the obstructed and unobstructed environments. The results of RTK GPS and RTK GPS/Galileo obtained at different times of the same day by using two reference points were compared. The results of this study illustrate that integrating RTK GPS system with Galileo is favorable for surveying applications (cm accuracy). This study shows that in surveying applications requiring centimetre accuracy, the RTK GPS/Galileo method can replace other survey methods (Total Station).
PubDate: Mon, 06 Jun 2022 00:00:00 GMT
- Proposed single-zone map projection system for Turkey
Abstract: The coordinate base of the maps or sheets produced is the Universal Transversal Mercator (UTM) conformal projection, and it is not possible to work in a single coordinate system in Turkey. Therefore, a transition from UTM to other conformal projections is required. For the countries extending in an east–west UTM zone width like Turkey, composite projection (CP), a double standard paralleling Lambert Conformal Conic (LCC) and double map projections (DP) are used widely. However, this process causes increase in working load and processing errors by users. This study aims to determine a common projection system that can be used in the whole country. In this context, a composite projection from UTM and LCC projection has been defined for the first time. According to the results obtained, map projection CP with the least distortion values in both east–west and north–south directions has been chosen. With the CP selection, a single coordinate system has been determined for medium- and large-scale maps. Projection correction formulas, scale factor and false origin have been determined for map coordinates in CP. These distortions are obtained with a difference of less than 1 cm for 1 km long sides and less than 0.003″ for the azimuth value of this side, when the correction formulas are used.
PubDate: Mon, 03 Jan 2022 00:00:00 GMT
- Validation of the accuracy of geodetic automated measurement system based
on GNSS platform for continuous monitoring of surface movements in
post-mining areas
Abstract: The problem involving the monitoring of surface ground movements in post-mining areas is particularly important during the period of mine closures. During or after flooding of a mine, mechanical properties of the rock mass may be impaired, and this may trigger subsidence, surface landslides, uplift, sinkholes or seismic activity. It is, therefore, important to examine and select updating methods and plans for long-term monitoring of post-mining areas to mitigate seismic hazards or surface deformation during and after mine closure. The research assumed the implementation of continuous monitoring of surface movements using the Global Navigation Satellite System (GNSS) in the area of a closed hard coal mine ‘Kazimierz-Juliusz’, located in Poland. In order to ensure displacement measurement results with the accuracy of several millimetres, the accuracy of multi-GNSS observations carried out in real time as a combination of four global navigation systems, Global Positioning System (GPS), Globalnaja Navigacionnaja Sputnikova Sistema (GLONASS), Galileo and BeiDou, was determined. The article presents the results of empirical research conducted at four reference points. The test observations were made in variants comprising measurements based on: GPS, GPS and GLONASS systems, GPS, GLONASS and Galileo systems, GPS, GLONASS, Galileo and BeiDou systems. For each adopted solution, daily measurement sessions were performed using the RTK technique. The test results were subjected to accuracy analyses. Based on the obtained results, it was found that GNSS measurements should be carried out with the use of three navigation systems (GPS, GLONASS, Galileo), as an optimal solution for the needs of continuous geodetic monitoring in the area of the study.
PubDate: Thu, 30 Dec 2021 00:00:00 GMT
- Detection of periodic displacements of shell structures with edges using
spline surfaces, meshes and point clouds
Abstract: This research paper tackles the problem of determining displacements of complex-shaped shell structures, measured periodically using laser scanning. Point clouds obtained during different measurement epochs can be compared with each other directly or they can be converted into continuous models in the form of a triangle mesh or smooth patches (spline functions). The accuracy of the direct comparison of point clouds depends on the scanning density, while the accuracy of comparing the point cloud to the model depends on approximation errors that are formed during its creation. Modelling using triangle meshes flattens the local structure of the object compared to the spline model. However, if the shell has edges in its structure, their exact representation by spline models is impossible due to the undulations of functions along them. Edges can also be distorted by the mesh model by their chamfering with transverse triangles. These types of surface modelling errors can lead to the generation of pseudo-deformation of the structure, which is difficult to distinguish from real deformation. In order to assess the possibility of correct determination of deformation using the above-mentioned methods, laser scanning of a complex shell structure in two epochs was performed. Then, modelling and comparison of the results of periodic measurements were carried out. As a result of the research, advantages and disadvantages of each method were identified. It was noticed that none of the methods made it possible to correctly represent all deformations while suppressing pseudo-deformation. However, the combination of their best qualities made it possible to determine the actual deformation of the structure.
PubDate: Fri, 17 Dec 2021 00:00:00 GMT
- The method of detection and localization of configuration defects in
geodetic networks by means of Tikhonov regularization
Abstract: In adjusted geodetic networks, cases of local configuration defects (defects in the geometric structure of the network due to missing data or errors in point numbering) can be encountered, which lead to the singularity of the normal equation system in the least-squares procedure. Numbering errors in observation sets cause the computer program to define the network geometry incorrectly. Another cause of a defect may be accidental omission of certain data records, causing local indeterminacy or lowering of local reliability rates in a network. Obviously, the problem of a configuration defect may be easily detectable in networks with a small number of points. However, it becomes a real problem in large networks, where manual checking of all data becomes a very expensive task. The paper presents a new strategy for the detection of configuration defects with the use of the Tikhonov regularization method. The method was implemented in 1992 in the GEONET system (www.geonet.net.pl).
PubDate: Fri, 17 Dec 2021 00:00:00 GMT
- Determining the area corrections affecting the map areas in GIS
applications
Abstract: Nowadays, there are many area-based Geographic Information Systems (GIS) applications such as real estate valuation, land tax, farming support and cost–benefit analysis. Areas used in such applications are calculated by means of two-dimensional plane geometry. However, the computed area value is not the exact area value in the terrain. In order to calculate the exact area value of a parcel, area corrections due to various factors must be taken into account. These factors are selection of projection, slope of the terrain, elevation of the terrain and scale of the map. Selection of projection and slope of terrain are available; elevation of the terrain and scale of map are not available in all GIS software. In this study, the effect of area corrections on the area value calculated from the map is examined with sample applications and the results are presented to the GIS users. According to the results, GIS users should select the equal area projection. In addition, scale of map, elevation and slope of terrain should be taken into account in the area calculation where land measurements are not possible.
PubDate: Sat, 11 Dec 2021 00:00:00 GMT
- Possibility of applying geoinformation multiagent optimisation for
planning the development of road networks
Abstract: In recent years, computational intelligence has been used to solve optimisation problems. An innovative direction in the development of artificial intelligence methods is multiagent methods of intellectual optimisation, which simulate the collective behaviour of insects, animals and other living beings. It indicates the effectiveness of their behaviour, and hence the effectiveness of these methods, and the ability to be involved in solving applied problems. This article is devoted to the study of the development of road transport networks using the metaheuristic ant method of optimisation based on a number of data. The initial data were geospatial layers of information on slope steepness, engineering structures, forests, perennials, land development and hydrographic objects. The parameters of the behaviour of the studied method under different conditions and volumes of input geospatial data are experimentally established. The Max–Min method of multiagent optimisation is modified. The proposed modification takes into account the functional distance – the coefficient of the complexity of the route, which affects its length. This modification had an effective influence on the behaviour of ants and the choice of optimal routes, taking into account the terrain as one of the factors. The result of the advancement is an informational system, which is capable of formulating flexible options for passing optimal alternative routes between specified settlements.
PubDate: Tue, 26 Oct 2021 00:00:00 GMT
- 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 + ACXAT) for the observation vector L, the parameter vector X is estimated in the form of the derived formula X^=(CX−1+ATPA)−1ATP⋅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.
PubDate: Sun, 25 Jul 2021 00:00:00 GMT
- Development of a UAV-based system for the semi-automatic estimation of the
volume of earthworks
Abstract: One of the challenges faced by surveyors in acquisition of accurate spatial data for mining applications is the risk involved in acquiring data in rugged terrains and difficult or inaccessible areas. With the advent of modern technology, accurate geospatial data can now be safely obtained for proper mining documentation periodically. The use of Unmanned Aerial Vehicles (UAVs) for data acquisition in mine surveying has been a viable means of obtaining reliable geospatial data rapidly and efficiently. The main goal of this study is to develop a semi-automatic UAV-based system for the acquisition of spatial data required for the estimation of the volume of earthworks. A DJI Phantom 4 quadcopter was used for the acquisition of image data of the project site, while the images were processed into a Digital Elevation Model (DEM) using Pix4Dmapper v2.0.1, which was then imported into the MATLAB-based system developed for the automatic estimation of the volume of earthworks. The volume obtained from the automated system was thus compared with the volume obtained directly from the Pix4Dmapper software, having specified a contour interval of 1 and an allowable error rate of ±3% as the standard error. While ±1.02% error was observed in the volume estimated using the Pix4Dmapper, the developed automated system yielded an estimated precision of ±0.81% in its volume estimation, which proves to be more robust for automatic volume estimation in terms of accuracy and precision.
PubDate: Thu, 31 Dec 2020 00:00:00 GMT
- Monitoring and forecasting spatio-temporal LULC for Akure rainforest
habitat in Nigeria
Abstract: For several decades, Nigerian cities have been experiencing a decline in their biodiversity resulting from rapid land use land cover (LULC) changes. Anticipating short/long-term consequences, this study hypothesised the effects of LULC variables in Akure, a developing tropical rainforest city in south-west Nigeria. A differentiated trend of urban LULC was determined over a period covering 1999–2019. The study showed the net change for bare land, built-up area, cultivated land, forest cover and grassland over the two decades to be −292.68 km2, +325.79 km2, +88.65 km2, +8.62 km2 and −131.38 km2, respectively. With a projected population increase of about 46.85%, the study identified that the built-up land cover increased from 1.98% to 48.61%. The change detection analysis revealed an upsurge in built area class. The expansion indicated a significant inverse correlation with the bare land class (50.97% to 8.66%) and grassland class (36.33% to 17.94%) over the study period. The study observed that the land consumption rate (in hectares) steadily increased by 0.00505, 0.00362 and 0.0687, in the year 1999, 2009 and 2019, respectively. This rate of increase is higher than studies conducted in more populated cities. The Cellular Automata (CA) Markovian analysis predicted a 37.92% growth of the study area will be the built-up area in the next two decades (2039). The 20-year prediction for Akure built-up area is within range when compared to CA Markov prediction for other cities across the globe. The findings of this study will guide future planning for rational LULC evaluation.
PubDate: Thu, 31 Dec 2020 00:00:00 GMT
- Legal aspects of registration the time of cadastral data creation or
modification
Abstract: In Poland, the cadastre is the basic register which is the source of information on cadastral entities and their property. Therefore, it should constitute a reliable source of information in the scope of establishing the range of law, its nature, but also the subject of its ownership. However, it is necessary to be able to not only check the current information on the legal status and its scope, but also review past statuses or determine the rights that will influence real estate in the future. The cadastre and related rights are changing very dynamically over time, and each state has a very strict reference to the previous state. Therefore, in order to manage real estate in the most effective way, it is necessary to record temporal attributes of cadastre objects.The main objective of this paper is to define the legal issues related to the possibility of registration at the time of creation or modification of object in the Polish cadastre. This paper includes analyses of both Polish legal regulations and European standards and norms. Moreover, the article presents the results of comparative analyses concerning the data model of cadastre and INSPIRE and Land Administration Domain Model (LADM) data models for the theme cadastral parcel in terms of temporal aspect.
PubDate: Fri, 25 Sep 2020 00:00:00 GMT
- Stereophotogrammetry for 2-D building deformation monitoring using Kalman
Filter
Abstract: Stereo photogrammetry has been used in this study to analyse and detect movements within the Lecture theater of School of Environmental Technology of Federal University of Technology Minna via the use of Kalman filter algorithm. The essential steps for implementation of this method are herein highlighted and results obtained indicate Ins. Mov.s (velocity) ranging from ±0.0000001 m/epoch to ±0.000007 m/epoch with greater movements noticed in the horizontal direction than in the vertical direction of the building. Because the observed movements were insignificant, the building has been classified as stable. However, a longer period of observation with a bi-monthly observational interval has been recommended to enable decision on the rate of rise/sink and deformation of the building.
PubDate: Fri, 07 Aug 2020 00:00:00 GMT
- Development of a precise local quasigeoid model for the city of Krakow
– QuasigeoidKR2019
Abstract: A geoid or quasigeoid model allows the integration of satellite measurements with ground levelling measurements in valid height systems. A precise quasigeoid model has been developed for the city of Krakow. One of the goals of the model construction was to provide a more detailed quasigeoid course than the one offered by the national model PL-geoid2011. Only four measurement points in the area of Kraków were used to build a national quasigeoid model. It can be assumed that due to the small number of points and their uneven distribution over the city area, the quasigeoid can be determined less accurately. It became the reason for developing a local quasigeoid model based on a larger number of evenly distributed points. The quasigeoid model was based on 66 evenly distributed points (from 2.5 km to 5.0 km apart) in the study area. The process of modelling the quasigeoid used height anomalies determined at these points on the basis of normal heights derived through levelling and ellipsoidal heights derived through GNSS surveys. Height anomalies coming from the global geopotential model EGM2008 served as a long-wavelength trend in those derived from surveys. Analyses showed that the developed height anomaly model fits the empirical data at the level of single millimetres – mean absolute difference 0.005 m. The developed local model QuasigeoidKR2019, similar to the national model PL-geoid2011, are models closely related to the reference and height systems in Poland. Such models are used to integrate GNSS and levelling observations. A comparison of the local QuasigeoidKR2019 and national PL-geoid2011 model was made for the reference frame PL-ETRF2000 and height datum PL-KRON86-NH. The comparison of the two models with respect to GNSS/levelling height anomalies shows a triple reduction in the values of individual quartiles and a mean absolute difference for the developed local model. These summary statistics clearly indicate that the accuracy of the local model for the city of Krakow is significantly higher than that of the national one.
PubDate: Fri, 22 May 2020 00:00:00 GMT
- The influence analysis of criteria of comparables’ selection on the
accuracy of the property value estimation
Abstract: The subject of the considerations presented in the article is the question of the criteria according to which the comparables, in the market value estimating process, should be selected. As the most important in the selection of comparative properties, the factor of similarity in relation to the subject property (measured by the Euclidean distance) was considered. As the key issue, the similarity assessment criterion and the influence of the adopted critical value of this criterion on the accuracy of estimates were chosen. The analysis of the above was carried out with taking into account the role of the significance of independent variables (measured by their correlation with the vector of the dependent variable). The results of the simulation tests carried out in the variants set by the criteria adopted were presented. On this basis, it has been shown that there is a potential most relevant solution in the collection of obtainable estimation results. This solution corresponds with the smallest sum of the differences of model prices (accepted as known) and corresponding estimates. The found minimum occurs for a specific layout of the above criterion values only.
PubDate: Tue, 21 Apr 2020 00:00:00 GMT
- The conversion of heights of the benchmarks of the detailed vertical
reference network into the PL-EVRF2007-NH frame
Abstract: The paper describes the problem of conversion of heights to the European Vertical Reference Frame 2007 for Poland (PL-EVRF2007-NH). The subject of the study is height data, and especially the detailed vertical reference network. The aim of the article is to present an alternative method of conversion to the one recommended by the Polish Head Office of Geodesy and Cartography. The proposed approach is characterised by a low implementation cost while maintaining the required accuracy.The publication is illustrated by the case of Kętrzyn district (in the north-east part of Poland). The local reference network was converted from Kronstad’60 to PL-EVRF2007-NH in 2017.
PubDate: Fri, 17 Jan 2020 00:00:00 GMT
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