Besides precise levels, precise leveling staffs are a crucial part of the measuring equipment when carrying out geodetic (geometric) leveling measurements. The leveling staffs define the scale of the ...height reference system, so it is important to calibrate them periodically and when necessary. This paper shortly describes the development of the new method of calibrating leveling staffs in the Laboratory for Measurements and Measuring Technique of the Faculty of Geodesy, University of Zagreb. The existing horizontal comparator was upgraded by installing a servo-motorized positioning drive with a mounted CCD camera and telecentric lens that is used to record graduations of the leveling staffs. The software was developed to support the management of the comparator system, as well as for the analysis and processing of images and measurement data and, most importantly, giving the result in the form of a calibration report. The main subject of this paper is a detailed assessment of the measurement uncertainty of determining the position of the edges of the graduation lines and determining the scale of precise centimeter and coded leveling staffs. The estimates were confirmed by experimental measurements.
AbstractSome errors that affect the accuracy of electronic distance measurement (EDM) instruments can be determined in a laboratory, but most are detectable and measurable only on a calibration ...baseline on which distances are precisely determined. In this paper, precise distance determination is presented on the calibration baseline of the Faculty of Geodesy, University of Zagreb, Croatia, using a precise total station Leica TCA2003. The corrections and reductions for precise calibration baseline distance determination are described theoretically: additive constant, first and second velocity correction, periodic error correction, reduction to the baseline mean height using station heights (in two steps), reduction for horizontal transversal deviation of the baseline, and scale error correction. Field distance and atmospheric parameter measurements are explained, with testing of periodic errors and scale error. In postprocessing, measured distances are corrected and reduced by applicable corrections and reductions, and subsequently adjusted using a Gauss-Markov model with the least-squares principle. Final distances are given with their uncertainty, together with a standard uncertainty evaluation for 1,000-m distance measurement according to current international standards.
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.
Hydropower plants are objects which horizontal and vertical displacement must be monitored regularly. Method used for determination of horizontal displacements of the Hydropower plant Mostar in ...Bosnia and Herzegovina, and its practical execution are presented. Algorithms for regular adjustment of indirect measurements and Stransformations into optimal datum are also presented in this paper. Further, regular adjustments of indirect measurements of the reference and control point coordinates in the conventional datum are performed for two epochs of measurements (December 2014 and June 2015). For each epoch regular adjustments are performed in a way that two base points are fixed, and all the other points, reference and control, are adjusted simultaneously. For adjusted values, in both cases, the S-transformation algorithm is used for transformation from conventional to optimal datum. Horizontal displacements are calculated between those two epochs, as well as regarding zero-epoch (year 1988). The analysis of the obtained position displacements is given, as well as the recommendations for the future series of measurements.
When determining height differences by using trigonometric levelling method, some affecting values are present. Besides measuring imperfection due to instrumental imperfection and surveyor's errors, ...quality of the trigonometric levelling results also depends on following external affecting values: height difference between observed points, distance between observed points and temperature gradient (change of temperature with height) between observed points. Therefore, if the height difference is bigger, the influence of vertical refraction on the sightline is bigger. Also, temperature gradient in layers of air directly affects the sightline, that is, on the measuring of vertical angles. When distance between observed points is longer, the effect of Earth's curvature is bigger, so, to eliminate this effect, trigonometric levelling was conducted between relatively close points, approximately 200-meter distant. Besides that, levelling was conducted by means of two different methods to obtain partially independent height differences between close points. In that way, it was possible to calculate the refraction influence from difference of the results obtained by two methods.
SOFTWARE SUPPORT FOR FREE GEODETIC NETWORKS ADJUSTMENT Zrinjski, Mladen; Baričević, Sergej; Barković, Ðuro ...
International Multidisciplinary Scientific GeoConference : SGEM,
01/2017, Volume:
17
Conference Proceeding
Free geodetic networks are networks of points which absolute coordinates are not known, but only their relative position in relation to each other. This network is invariant to translation and ...rotation, and possibly a change in the scale. Degrees of freedom of this type of network cause singularity of the normal equations coefficient matrix N, therefore the use of general inverse is required, and the most commonly used is Moore-Penrose inverse or pseudoinverse. This paper presents available commercial software which are most commonly used in geodetic practice for network adjustment, regular, as well as singular. The mathematical solution of singular networks adjustment has been elaborated, input and output values were defined and consequently the application flowchart was made. By use of programming language C# in .NET framework in Microsoft Visual Studio, the Windows application called NetAdjustment has been developed for the adjustment of levelling and two- and three-dimensional trilateration free networks.
Laboratorij za mjerenja i mjernu tehniku jedna je od ustrojbenih jedinica Geodetskog fakulteta Sveučilišta u Zagrebu. U Laboratoriju se razvijaju nove mjerne metode i uređaji za ispitivanje i ...umjeravanje geodetskih instrumenata i pribora u skladu s međunarodnim i nacionalnim normama. U Laboratoriju se obavlja nastavna, znanstveno-istraživačka i stručna djelatnost. U radu su opisane dvije doktorske disertacije i dva diplomska rada koji su izrađeni u Laboratoriju, a koji pobliže ističu izazove znanstveno-istraživačkog rada. Opisan je jedan doktorski rad koji je u završnoj fazi izrade, kako bi se prikazao razvoj Laboratorija u predstojećem razdoblju.
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