This study investigates the optimal distribution and pattern of ground control points (GCPs) in aerial photogrammetric projects. Aerial triangulation (AT), also known as bundle adjustment, is the ...fundamental step in refining 3D reconstruction models and camera positions, thereby minimizing reprojection errors. The study utilizes data from a national project in Romania, employing high-resolution aerial images acquisition using photogrammetric sensors. The project has rigorous requirements of ground control points (GCP) placement and field measurements using GNSS and geometric leveling techniques. The study employs various scenarios, manipulating the number and distribution of GCPs, to assess their influence on planimetric and altimetric accuracy. Results indicate that the configuration and number of GCPs significantly affect the accuracy of photogrammetric products, such as dense image point clouds, digital surface models, and orthophotos. Moreover, the study underscores the importance of precise GCP determination methods, especially in regions lacking a precise gravimetric geoid model. In scenarios with inadequate GCP coverage the outcomes have inferior quality, emphasizing the critical role of GCPs in ensuring the quality of photogrammetric products. Overall, the research gives a clear view on the best placement patterns of GCPs and their influence on AT process evaluation performed in check points (CHKs).
U ovom radu je opisana metoda geometrijskog nivelmana s posebnim fokusom na nivelman visoke točnosti i precizne nivelmanske letve. Navedeni su i objašnjeni utjecaji nesavršenosti preciznih ...nivelmanskih letvi na mjerenja u nivelmanu visoke točnosti, kao i metode modeliranja, minimiziranja i eliminacije sustavnih pogrešaka letvi. Također su opisani pojam i proces umjeravanja preciznih nivelmanskih letvi te razvoj metoda i komparatora za umjeravanje s fokusom na komparatore s integriranom CCD kamerom. Pobliže je opisan komparator Laboratorija za mjerenje i mjernu tehniku Geodetskog fakulteta Sveučilišta u Zagrebu, te je prezentiran plan njegova osuvremenjivanja razvojem nove metode umjeravanja geodetskih linearnih mjerila integriranjem CCD kamere.
•High-precision topographic total stations are used to cross impassable areas.•Trigonometric levelling is proposed as an alternative to geometric levelling.•The procedure is based on a reciprocal and ...simultaneous levelling scheme.•The right geometrical and timing schedule, and the calibration of ATR are required.
With the arrival on the market of high-precision topographic total stations, professionals today, using appropriate methodologies, can determine altimetric connections to an accuracy that is almost comparable to those obtainable using high-precision geometric levelling. This aspect is of particular interest when it is not possible to proceed with classical geometric levelling operations due to logistical or other reasons: for instance, where levelling lines need to cross impassable areas such as streams, soft soils or canyons. Currently, height differences between two points separated by an impassable area are mainly measured using optical-mechanical levels by procedures that present a number of difficulties. This work presents the results achieved through several trials conducted on the use of high precision trigonometric levelling for measurement of height difference between benchmarks at opposite sides of streams. In particular, it describes the project where simultaneous and reciprocal measures were taken using two high-precision robotic total stations.
Relevance. Nowadays the list of engineering geodetic survey with the soils with seasonal frost, which has been developed and applied now, require further studies of permafrost soils relating to ...development of technique of generating geodetic control and delivering stability of this control sections at different stages of its development. These issues are of great importance at construction and operation of energy sites at permafrost soils. The aim of the research is to develop and introduce the process chart of developing stable field compilation survey under conditions of permafrost soils at Nyagan and Seversk District Power Plants (Nyagan, Khanty-Mansiisk autonomous district). Subjects: ground benchmarks, construction netting items, fundamental geodetic points, general geodetic points, permafrost soils. Methods: free station method, back linear-angular sight, satellite observations, determination of space position of cooling tower frame, geometric levelling by short beams, observation over precipitation and deformation of buildings, constructions and main equipment. Results. The authors have proposed the processing chart of geodetic monitoring in permafrost soils. The paper introduces the diagram of fundamental geodetic point, which is capable of conserving stable space position during construction and installation activities and at operation of power plants. The authors developed the technique of deformation monitoring of cooling tower with different frame shape. The developed technique allows determining the space position of the cooling tower frame at different operation modes of the main equipment with power from 0 to 100 %, with root-mean square error not more than 2,0 mm.
The strict mathematical model of the mobile precise trigonometric levelling (MPTL) is deduced and its error sources are analysed in this paper. Some position sensors are added to instruments and ...observing reciprocal at the same time using two modified measuring robots so as to reduce the influence of atmospheric refraction, curvature of the earth and other factors. It is not necessary to measure the heights of instruments and targets by constructing the even numbers of observed edges to avoid errors of measuring heights. Experimental results indicate that MPTL has greatly increased the working efficiency and reduced the labour intensity compared with precise geometric levelling in the hills and mountains. A large number of experiments have proved that the standard deflection of measurement is less than
and with an average speed of more than 7 kilometres per day in mountainous terrain.
Relevance. Nowadays the list of engineering geodetic survey with the soils with seasonal frost, which has been developed and applied now, require further studies of permafrost soils relating to ...development of technique of generating geodetic control and delivering stability of this control sections at different stages of its development. These issues are of great importance at construction and operation of energy sites at permafrost soils. The aim of the research is to develop and introduce the process chart of developing stable field compilation survey under conditions of permafrost soils at Nyagan and Seversk District Power Plants (Nyagan, Khanty-Mansiisk autonomous district). Subjects: ground benchmarks, construction netting items, fundamental geodetic points, general geodetic points, permafrost soils. Methods: free station method, back linear-angular sight, satellite observations, determination of space position of cooling tower frame, geometric levelling by short beams, observation over precipitation and deformation of buildings, constructions and main equipment. Results. The authors have proposed the processing chart of geodetic monitoring in permafrost soils. The paper introduces the diagram of fundamental geodetic point, which is capable of conserving stable space position during construction and installation activities and at operation of power plants. The authors developed the technique of deformation monitoring of cooling tower with different frame shape. The developed technique allows determining the space position of the cooling tower frame at different operation modes of the main equipment with power from 0 to 100 %, with root-mean square error not more than 2,0 mm.
Obnavljanje visinskog sustava periodičan je proces kojem je svrha da se različitim korisnicima kontinuirano osigura kvalitetan, pouzdan i ažuran visinski podatak. Zbog zastarjelosti visinskih ...podataka Republici Hrvatskoj predstoji obnova referentnoga visinskog sustava. U radu se istražuje kako su neke europske zemlje pristupile rješavanju tog problema te se na pregledan način prikazuju visinski sustavi u tim zemljama. Prilikom obnove temeljne mreže geometrijskog nivelmana u Republici Hrvatskoj morat će se uzeti u obzir činjenica da su na prostoru bivše zajedničke države nastale nove države, potreba za prihvaćanjem novoga visinskog sustava (normalni ili ortometrijski) te važnost nivelmanskih vlakova u susjednim državama za konfiguraciju nacionalne temeljne nivelmanske mreže.
The article present processing techniques of radar data for calculating the deformations of the earth’s surface on the example of minefield, that is situated under the exogenous influence of ...underground workings of the “Khotin” minery Kalush-Golinskyy deposit. The estimation of accuracy of radar image processing methods, namely, the interferometry of the permanent radar scatterers and the interferometry of a series of small baseline lines, is made, by comparison with the results of processional geometric levelling with a short beam of deformation soil rappers of the profile lines of the mine field. On the basis of geodetic instrumental field observations, shells of sediments of the earth’s surface were constructed and the boundaries of zero deposition caused by deformation processes in the area of hollow fields were established. Working out of an array of measurements by two methods of interferometry allowed to put on the digital map the data that reflect the average sedimentation rates in the year at the radar measurement locations. Due to the ranking of average annual sedimentation rates, areas of interest were outlined where significant precipitation was observed. This made it possible to assert that the earth’s crust was caused by the anthropogenic influence on the Khotin miner, which was observed since 1977 and continues existing, albeit at lower speeds. The use of expensive and labour-intensive processional levelling only on pre-determined problem areas is rational both from a scientific and from a production point of view, as it allows better use of material and human resources. Therefore, there is a need for an integrated monitoring system to prevent an exogenous catastrophe on an ongoing basis.
The Partido Stream is a small torrential course that flows into the marsh of the Doñana National Park, an area that was declared a World Heritage Site in 1994. Before 1981, floods occurred, and the ...stream overflowed onto a floodplain. As an old alluvial fan, the floodplain has its singular orography and functionality. From the floodplain, several drainage channels, locally called caño, discharged into the marsh. The Partido Stream had the morphology of a caño and covered approximately 8km from the old fan to the marsh.
The stream was straightened and channelised in 1981 to cultivate the old fan. This resulted in floods that were concentrated between the banks in the following years, which caused the depth of water and the shear stress to increase, thus, scouring the river bed and river banks. In this case, the eroded materials were carried towards the marsh where a new alluvial fan evolved.
Control measures on the old fan were implemented in 2006 to stop the development of the new alluvial fan downstream over the marsh. Thus, the stream would partially recover its original behaviour that it had before channelisation, moving forwards in a new, balanced state. The present study describes the geomorphological evolution that channelisation has caused since 1981 and the later slow process of recovery of the original hydraulic-sedimentation regime since 2006. Additionally, it deepens the understanding of the original hydraulic behaviour of the stream, combining field data and 2D simulations.
•We simulate the original stage of an old flooding area.•A previous study of the local geomorphology will avoid sedimentary imbalances.•A few civil engineering infrastructures bring partially recovered scenarios.•2D hydrological simulating softwares are a useful tool for environmental management.
As a result of different works on the buildings wall (insulation, installing billboards or mailboxes, etc.) the access to the existing benchmarks may be hindered and as a result it may be difficult ...to perform geometric levelling using classical measuring equipment. For this reason, the authors have developed and created a prototype of a mechanical benchmark snap-in. Its construction and principle of operation are presented in this paper. As part of the research and experimental works carried out under the laboratory conditions the instrument was calibrated and its functionality and accuracy were designated. On the basis of height differences between benchmarks which were determined using the benchmark snap-in, it was found that the average accuracy of the height difference designation under the laboratory conditions, where the length of the line of sight is 4 m, does not exceed ± 0.01 mm. Keywords: Geometric levelling Engineering measurements of elevation Benchmark snap-in
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