Ústav geodézie

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Intercomparison of multi-GNSS signals characteristics acquired by a low-cost receiver connected to various low-cost antennas
(Springer, 2024-03-08) Marut, Grzegorz; Hadas, Tomasz; Nosek, Jakub
With the increasing number of low-cost GNSS antennas available on the market, there is a lack of comprehensive analysis and intercomparison of their performance. Moreover, multi-GNSS observation noises are not well recognized for low-cost receivers. This study characterizes the quality of GNSS signals acquired by low-cost GNSS receivers equipped with eight types of antennas in terms of signal acquisition, multipath error and receiver noise. The differences between various types of low-cost antennas are non-negligible, with helical antennas underperforming in every respect. Compared with a geodetic-grade station, GPS and Galileo signals acquired by low-cost receivers are typically weaker by 3–9 dB-Hz. While the L1, E1 and E5b signals are well-tracked, only 72% and 86% of L2 signals are acquired for GPS and GLONASS, respectively. The signal noise for pseudoranges varies from 0.12 m for Galileo E5b to over 0.30 m for GLONASS L1 and L2, whereas for carrier-phase observations it oscillates around 1 mm for both GPS and Galileo frequencies, but exceeds 3 mm for both GLONASS frequencies. Antenna phase center offsets (PCOs) vary significantly between frequencies and constellations, and do not agree between two antennas of the same type by up to 25 mm in the vertical component. After a field calibration a of low-cost antenna and consistent application of PCOs, the horizontal and vertical accuracy is improved to a few millimeter and a few centimeter level for the multi-GNSS processing with double-differenced and undifferenced approach, respectively. Last but not least, we demonstrate that PPP-AR is possible also with low-cost GNSS receivers and antennas, and improves the precision and convergence time. The results prove that selection of low-cost antenna for a low-cost GNSS receiver is of great importance in precise positioning applications.
Automatic Creation of 3D Documentation in CAD/BIM Based on Topology
(MDPI, 2023-08-01) Bartoněk, Dalibor
This paper deals with reverse engineering, namely the as-built documentation of actual construction. The input is data measured in the field using geodetic methods. In addition to modern methods of surveying 3D objects, such as laser scanning, it is still necessary to use classic surveying using a total station. The bottleneck of the process is the creation of documentation of the construction, which is still created manually in the appropriate CAD/BIM software. The goal of this research was to find a method that would reduce the amount of manual work when drawing documentation in CAD/BIM to a minimum. The core of the solution is the use of a topology that interconnects the points measured in-field. The entire procedure has two parts: (1) creating a topological drawing template in a suitable CAD/GIS software (digital sketch) and (2) adding geometry to this sketch and creating a drawing using topological codes. This method was verified in practice by applying it to several specific buildings in the Czech Republic. The practical application of the method demonstrated 30% time savings and a reduction in work and error rate in the entire process.
The Possibilities of Bim Quality Control in the Game Development Environment
(ISPRS, 2022-02-07) Volařík, Tomáš; Kuruc, Michal; Kratochvíl, Richard; Vystavěl, Ondřej
The quality control of the BIM model to be delivered is one of the most important steps in the process of information modelling. Quality control can take place on several levels. First of all, it is a control of geometric parameters, especially a control of the relative accuracy of the resulting model with respect to the modelled real object. Another type of quality control can be a check of the completeness of the model, whether the resulting model contains all the elements that are to be included in the model according to the requirements. MEP equipment such as fire extinguishers, for example, is a substantial content of BIM models. This may also be related to the required level of LOD, e.g. whether these elements are modelled with the required level of detail. Furthermore, the visual properties of the individual elements can be checked, for example whether the surface finish of the wall corresponds to reality. Subsequently, database and descriptive information of individual elements should be checked, such as technical parameters of various items of technical equipment of MEP content. This article describes variants of the publication of a building information model for the purposes of BIM model quality control. The procedure of creating the final application in the game development environment Unreal Engine (Epic Games) is described on the example of a BIM model of a historical building from the middle of the 19th century.
Recent Relative Vertical Movements in the Tectonic Zone of the Sudety Mts.
(IRSM AS CR, 2016-06-15) Kaczmarek, Adrian; Cacoń, Stefan; Weigel, Josef
Recent geodynamic activity of the Sudeten in the area of Poland and the Czech Republic has been confirmed by the results of geodynamic, seismic, geodetic and other tests. This is especially the case for the periodical (the last 25 years) satellite GPS/GNSS and gravimetric measurements in the regional research network GEOSUD, SILESIA, SUDETY and the local geodynamic polygons ("Snieznik", "Stolowe Mts."), as well as observation of crack-gauges on several tectonic faults. Vertical movements are indicated in the maps of recent movements of the Earth’s crust. Two adjacent countries in the area of the Sudeten achieved results from +0.5 mm/year to -2 mm/year with reference to the tide gauge on the coast of the Baltic Sea. They present absolute value received on the basis of a comparison of the results of repeated (in intervals of 20–30 years) measurements of 1st order levelling lines. The characteristics of this data do not allow for an assessment of recent tectonic activity in the Sudety Mts. because the isolines of absolute velocities of vertical movements of the Earth’s crust surface on the maps (Wyrzykowski, 1985; Kowalczyk, 2006; Vyskočil, 2002) present "smoothed" large-area changes without a proof of dynamic changes in the Sudeten tectonic zones. This paper presents results of analysis archival data on repeated measurement precise levelling networks. The results of analysis were used to produce maps of vertical movements of the Earth’s crust surface. Analysis is focused on the part of levelling lines which intersect Sudeten main tectonic faults. This paper included methodology of data processing. In research period relative vertical movements of tectonic zones are referencing to the relative stable benchmark. The values of these velocities between -0.8 ÷ +0.8 mm/year confirm recent geodynamic mobility in this Central European area.
Method for Cartographic Symbols Creation in Connection with Map Series Digitization
(MDPI, 2022-02-02) Bartoněk, Dalibor; Andělová, Pavla
The article addresses the issue of the unification of cartographic symbols in terms of graphics (visual) and interpretation in an international context. The motivation is the ongoing dig-itization of processes in the conditions of Industry 4.0, especially Construction 4.0, where geodesy and cartography have their irreplaceable share. The aim was both to design uniform cartographic symbols for the description of geographical objects on the map and to design a general method for the description of unified cartographic symbols so that it is independent of specific applications. The authors compared the symbols used in the map works of the Czech Republic and neighboring countries that are members of the EU and proposed a formal description of the graphics properties of the symbols, which is based on a general mathematical model based. The description takes the form of a text string, and a Python algorithm was built to render the symbol built and implemented in the QGIS environment. The article also presents a comparison of some cartographic symbols used in the Czech Republic and in selected EU countries and a proposal for their unification. The motivation is the effort to unify the cartographic language within the EU. The problem is in ac-cordance with the INSPIRE directive (seamless map of Europe) at the international level and with the Digital Czechia 2018+ strategy at the national level.

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