Two adjustments of the second levelling of Finland by using nonconventional weights

Cvetkov, Vasil

doi:10.1515/jogs-2022-0148

Cited by 5 publications

(4 citation statements)

References 7 publications

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“…Rekus [9] and Saaranen [17] analysed robotized digital levelling in its practical applications. Yaprack [11] and Cvetkov [18] devoted their research to digital level applications in precise height systems. Besides field measurements, technological progress and automation also affected the calibration process of levelling systems.…”

Section: An Overview Of Levelling Error Theoriesmentioning

confidence: 99%

The Effect of Critical Distance in Digital Levelling

Izvoltova,

Chromcak,

Bacova

2024

Computation

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Critical distance concerns precise digital levelling, which has inaccurate results at a certain sighting distance. The influence of critical distance on a measured height difference has been confirmed by calibrating certain digital levels and their appropriate code devices on a vertical comparator under laboratory conditions. The paper aims to explore the influence of critical distance on height differences obtained by precise digital levels of Leica NA3003 and DNA03 by experimental measurements realised in situ. The processing of the measurement results consisted of defining a random error on a station by using parameter estimation of an error model to specify a partial error on a station dependent on sighting distance. Then the processing phase continues with the finding of the relation between the sighting distance and the dispersion of height differences acquired by digital levelling under terrain conditions. The theoretical part involves the development of levelling accuracy theories that vary over time by view on random and systematic error propagation. The numerical and graphical solution of the experimental measurements involves ordering the height differences into sighting groups according to the sighting distance. The standard deviation computed in each sighting group represents a measure of the dispersion of height differences. Suppose the standard deviation in the sighting group in both independent experimental locations K1 and K2 exceeds twice the total standard deviation. In that case, it is most likely considered to be the influence of the critical distance, which is then compared with values obtained by laboratory calibration of the same digital levels.

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Section: An Overview Of Levelling Error Theoriesmentioning

confidence: 99%

The Effect of Critical Distance in Digital Levelling

Izvoltova,

Chromcak,

Bacova

2024

Computation

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“…It is a common practice the weights wn to be given as a function of the length of a levelling line Ln [1, 9, 11] similar to equation ( 5) despite other weights are more statistically relevant [12,13].…”

Section: On the Impact Of The Network Configuration On The Final Accu...mentioning

confidence: 99%

“…Since the dawn of this method the mathematical treatment of levelling data has not been changed, supposing that the low of error and discrepancies accumulation, applied weights in the adjustment of levelling networks, etc., are absolutely clear. Some recent studies [12,13] show some cracks into the classical theory.…”

Section: Introductionmentioning

confidence: 99%

Geometryczne dane niwelacyjne i niektóre błędy systematyczne w ich przetwarzaniu

Cvetkov

2024

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The aim of this article is to illuminate some latent systematic faults in the mathematical treatment of precise levelling data. The first one is associated with the use of the average of both measurements of the height differences between the terminal benchmarks in levelling lines. Another weak point in the classical treatment of levelling data is the incomplete minimization of the impact of the spatial network configuration on the produced mean standard errors of the nodal benchmarks from the adjustment. Generating sixty random paired samples of size 1000, derived from three continuous distributions, e.g. Normal (0, 1), Uniform (-1.732, 1.732) and Gamma (1, 1), it was found that the average of two same distributed and ordered observations is very nearby to the theoretical expectation, in comparison to both observations, only in approximately 27-30% of all cases. Contrary, in other 70-74% of cases, either the “first” or the “second” observation is in close proximity to the expectation. The miss of this fact leads to a statistically significant deterioration of the final accuracy of the levelling networks. In the current study, it is also shown that the minimization of the standard errors of the adjusted normal heights of the nodal benchmarks in the Bulgarian Levelling Network 1980 cannot be achieved with the weights w=const.L-1, which are the most popular and used type of weights in the adjustment of geometric levelling networks. Finally, it is illustrated that taking into account the above marks and applying an appropriate adjustment algorithm, the mean of the standard errors of the adjusted heights of the nodal benchmarks in the analysed network is possible to be less than 1mm. The standard error of the adjusted height of the most remoted benchmark “Pushkarov”, which is 598 km far away from the datum point located in Varna, is equal to 1.40mm. The obtained from the adjustment mean standard error for the weight unit is estimated to be 0.164 mm/√km. In comparison, the adjustment mean standard error for the weight unit, but yielded by the classical approach of adjustment of the analysed network, is 1.289 mm/√km or almost 9 times higher. Despite being tedious and time-consuming, it is not on point of discarding the precise geometric levelling as a main geodetic method for solving of a couple of scientific and engineering tasks, where differences in heights have to be determined with the highest accuracy.

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“…The analysis of Table 2 shows, that the spirit levelling method has reached its limits (Cvetkov, 2023). The trend is therefore to emphasise the use of satellite levelling, based on a simple formula:…”

Section: Levelling Networkmentioning

confidence: 99%

Geodata in Science – A Review of Selected Scientific Fields

Apollo,

Jakubiak,

Nistor

et al. 2023

ASP.FC

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Aim of the study: Today, completely new forms of geo-information systems are becoming increasingly popular. New technological possibilities allow these systems to be adapted to the requirements and needs of societies. This paper is an extensive literature review of the use of geodata in various scientific fields, in STEM (science, technology, engineering, and mathematics) disciplines. However, as there is no universal agreement as to which disciplines are included in the STEM, the authors also included related fields such as geography or transport. Material and methods: Already a preliminary analysis of the Web of Science Core Collection database has shown that geodata is used very widely, in every scientific discipline analysed (with varying degrees of sophistication). The main objective of the paper is to provide a comprehensive analysis of the usage of geodata in five areas: bathymetric measurements, satellite geodata, aerial retrieved geodata, levelling networks, and GIS data. Results and conclusions: The results showed the increasing availability of data that can contribute to a better understanding and management of our planet. Geodata as a tool is overly broad and general, and it is used or might be used in every discipline of science.

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Two adjustments of the second levelling of Finland by using nonconventional weights

Cited by 5 publications

References 7 publications

The Effect of Critical Distance in Digital Levelling

The Effect of Critical Distance in Digital Levelling

Geometryczne dane niwelacyjne i niektóre błędy systematyczne w ich przetwarzaniu

Geodata in Science – A Review of Selected Scientific Fields

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