In the past, church belfries, due to their shape and higher layout, often served as reference points in surveying. With the development of satellite based positioning methods and the establishment of ...the D96/TM coordinate system, they slowly lost their significance. Nevertheless, unlike ground trigonometric points, they have remained largely intact. As such, they enable the determination of transformation parameters between the old and the new coordinate systems. Therefore, we need to determine their positions in the new coordinate system. In this paper, we describe the process of determining the position of church belfries using terrestrial laser scanning (TLS) in the case of both belfries of the Trnovo church. The process involves determining coordinates of the tie points for georeferencing the point clouds, which requires the determination of the geodetic datum by a combination of GNSS measurement and geometric levelling, and the classical geodetic survey of the geodetic network with free-network adjustment and further use of the S-transformation. Based on the georeferenced point clouds, we determined the position of the trigonometric point by sphere parameters adjustment. The data is filtered using the RANSAC so that we only have points that belong to the sphere in the adjustment process. The results were compared with the positions determined based on the classical terrestrial geodetic survey.
Continuous assessment of the displacement of a high-rise building enables verification that it meets the structural assumptions calculated in the project, and provides additional useful feedback for ...structural engineers. Unexpected structural responses during the phases of construction, or once the building is in use, can help detect current and future problems, as well as provide cost savings. Furthermore, it contributes to an improved risk management for natural phenomena and can be used to verify the stability of the structure, providing an additional safety layer for the building.
The technological improvement in global navigation satellite system (GNSS) techniques has allowed significant advancements of Gaussian methodologies applied to control the dynamics of building structures in real time, especially for calculating, controlling, and interpreting satellite survey measurements, based on Gaussian analysis and least squares adjustment.
The real-time monitoring system works by implementing a local geodetic network with GNSS technology on the structure to be monitored. Algorithms are then applied that improve the compensated network solution, and this is integrated into original software. The system allows us to achieve a high level of safety and effective risk management in real time, as a unique mathematical model that allows GNSS position errors to be reduced is designed for each building. In the case of Torre Espacio, the overall mathematical adjustment model reduces the maximum error by 40%. The system has been installed on a high-rise building, Torre Espacio, in Madrid, Spain, and is fully operational.
AbstractSeveral least-squares adjustment techniques were tested for dam deformation analysis. Deformation monitoring had only been studied horizontally. Simulated observations were first performed to ...compare the three methods of least-squares: observations with their initial weight, observations with the estimated variance component, and the regularization method. The best scenario was adopted for the real network. The results demonstrated that a more accurate outcome is possible by least-square variance component estimation (LS-VCE). Comparison of the estimated and simulated displacements in the LS-VCE method indicated that the difference for the two east–west and north–south components is 0.05 and 0.08 mm, while this difference in the other two modes is 1.02 and 0.67 mm for observations with their initial weight, and 0.64 and 0.16 mm for the Tikhonov regularization method, respectively. In the best method, an improvement was found in the standard deviation of the east–west, south–north components, the estimation of the major axis of the error ellipse, and the trace of the variance–covariance matrix of unknowns, in comparison with the other methods.
Recently, in Vietnam, the detection of geodetic measurements that contain rough errors as well as such data processing method has been considered as a key step in geodetic data processing, especially ...for large geodetic networks with many different types of measurements like 3D - Global Navigation Satellite Systems (GNSS) network. On the other hand, mines in Vietnam often have complex terrains, so it is necessary to apply modern and flexible surveying methods in combination with ground and space measurements to build 3D coordinates control networks for management and exploitation to ensure sustainable development. Therefore, this research developed a Robust estimation method based on empirical weighting function for establishing 3D geodetic network combining terrestrial observation and GNSS vectors. The experiment on processing the combined network in Lang Son limestone quarry, Vietnam showed that the proposed method could be an effective solution for processing 3D terrestrial – GNSS geodetic network for mine surveying in Vietnam.
The alpine environment with a high degree of nature protection is characterized by complete non-intervention. The processes and phenomena occurring in it are exclusively of a natural origin. Related ...geohazards are threatening the safety of people’s movement. They arise as a result of a combination of meteorological, hydrological, and geological–morphological factors permanently operating in the country. Therefore, the prevention of fatal events is limited to monitoring and predicting changes in selected objects where we expect change. Changes in the shape and dimension, or the object’s deformation, can be documented using geodetic and photogrammetric measurements. Our research focuses on monitoring a rock talus cone in High Tatras, Slovakia, at an altitude of 1700 m above sea level (ASL), created mainly due to erosion and seasonal torrential rains. To monitor changes in selected objects, we used mass non-contact methods of terrestrial laser scanning (TLS), UAS photogrammetry based on the principle of structure-from-motion–multi-view stereo (SfM–MVS), and airborne laser scanning (ALS). From the selective measurement methods, spatial measurement by a total station (TS) and height measurement based on the principle of precise leveling were used in the monitoring deformation network on a stand-alone boulder. The research results so far analyze and evaluate the possibilities, limits, effectiveness, and accuracy of the measurement and data processing methods used. As a result, we propose a complex methodology for monitoring similar phenomena in alpine environments.
A Geodetic Network is a network of point interconnected by direction and/or distance measurements or by using Global Navigation Satellite System receivers. Such networks are essential for the most ...geodetic engineering projects, such as monitoring the position and deformation of man-made structures (bridges, dams, power plants, tunnels, ports, etc.), to monitor the crustal deformation of the Earth, to implement an urban and rural cadastre, and others. One of the most important criteria that a geodetic network must meet is reliability. In this context, the reliability concerns the network's ability to detect and identify outliers. Here, we apply the Monte Carlo Method (MMC) to investigate the reliability of a geodetic network. The key of the MMC is the random number generator. Results for simulated closed levelling network reveal that identifying an outlier is more difficult than detecting it. In general, considering the simulated network, the relationship between the outlier detection and identification depends on the level of significance of the outlier statistical test.
Underwater photogrammetry is a well-established technique for measuring and modelling the subaquatic environment in fields ranging from archaeology to marine ecology. While for simple tasks the ...acquisition and processing of images have become straightforward, applications requiring relative accuracy better then 1:1000 are still considered challenging. This study focuses on the metric evaluation of different off-the-shelf camera systems for making high resolution and high accuracy measurements of coral reefs monitoring through time, where the variations to be measured are in the range of a few centimeters per year. High quality and low-cost systems (reflex and mirrorless vs action cameras, i.e. GoPro) with multiple lenses (prime and zoom), different fields of views (from fisheye to moderate wide angle), pressure housing materials and lens ports (dome and flat) are compared. Tests are repeated at different camera to object distances to investigate distance dependent induced errors and assess the accuracy of the photogrammetrically derived models. An extensive statistical analysis of the different systems is performed and comparisons against reference control point measured through a high precision underwater geodetic network are reported.
In the old coordinate system, church belfries often served as reference points in detail surveying. Consequently, their coordinates were regularly maintained in the geodetic databases of the old ...coordinate system. Their usability was significantly reduced by the establishment of the new coordinate system along with the use of satellite-based positioning methods and transformation models. Considering that the number of ground points of the old trigonometric geodetic networks decreases due to reconstruction, today they have gained practical value. Most of them were preserved in their original condition, which enables a continuous transition from the old to the new coordinate system as well as the reconstruction of the old situation on the basis of the old coordinate system data. They can be used in the determination of the transformation parameters of the detail or for the quality evaluation of the state transformation model. For this, their coordinates should be determined in the new coordinate system. The present article describes the determination of positions of five church belfries in the new coordinate system D96/TM, which are located in the southwestern part of Ljubljana. The procedure combines the determination of the geodetic network datum by GNSS, the inclusion of terrestrial measurements and free-network least squares adjustment and further use of the S-transformation. Further comparison of coordinates, acquired in different ways, shows some centimetre differences in each coordinate component for the given sample of church belfries. Therefore, for the sample under consideration, we can conclude that the Slovenian triangle-based transformation model effectively describes the transformation between the old and the new coordinate systems in the area under consideration.
In complex engineering objects such as dams, bridges, viaducts and other objects, deformations occur on them over time as a result of the external factors and the size of the objects themselves. In ...order to avoid potential disasters, these objects in certain time periods are supervised for potential deformations. There are a range of different methods of deformation analysis through which displacement of objects is determined. In this research a practical application of the Method of Mihajlovič is applied for determination of horizontal deformations of the “Mantovo” dam with the aim of analyzing the conducted results. In practical implementation two epochs of measurements are used, the first epoch from the year 1978 and the second epoch from the year 2008. From the conducted calculations it is confirmed that this methodology has its disadvantages in determination of the stable points that also affect the determination of the points that are located in the dam itself. This issue is overcome by setting more stable points when developing the network, these points should not be dislocated over time, but of course in natural environments this is difficult to achieve. The inability of determining the stable points is a major drawback that limits the practical implementation of this methodology.
Seafloor geodetic network (SGN) is the foundation for building an underwater positioning, navigation and timing (PNT) system. Traditional network deployment mainly focuses on the deployment of ...underwater sensor network nodes. However, for SGN, there is no surface buoy node and submarine buoy node, and the number of anchors is limited because it is quite expensive to fully cover large scale areas. To achieve wide coverage and good positioning service of each set of underwater base stations, we focus on the network design of a single set of reference stations in this paper. We propose several deployment plans for a local SGN and then analyze their service quality indicators by considering the stratification effect caused by non-uniformly distributed sound speed. To evaluate the performance of each topology of SGN, we compare their coverage range, horizontal dilution precision (HDOP) and accuracy performance of positioning tests. Based on the overall performance in our simulation, we believe that the star five-node topology is a good topology design under sufficient economic conditions.
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