Journal of Geodesy, Cartography and Cadastre - No 2 / 2015
Integral issue here
Table of Contents (technical articles)
Testing the accuracy of different calibration methods / Valeria Ersilia Oniga, Mircea Barbu Oniga, p. 8-17
GNSS analysis for geodynamics application / Sorin Nistor, Aurelian-Stelian Buda, Norbert-Szabolcs Suba, Gabriela Cîmpan, p. 18-26
Modern Means and Techniques for the Research upon the Analyse of the Subsidence Phenomenon / Maricel Palamariu, Ioan Voina, p. 27-33
Study on the efficiency of using motorized levelling in vertical geodetic networks / Constantin Chirilă, Cristian Onu, Alexandra Celestina Tulan, p. 34-39
Hypothesis verification models in leveling geodetic networks / Alexandra Radu, Constantin Coșarcă, p. 40-46
Testing the accuracy of different calibration methods
Valeria Ersilia Oniga, Mircea Barbu Oniga
Received: April 2015 / Accepted: June 2015 / Published: September 2015
Abstract
For many years, close-range photogrammetry has been dealing with the extraction of high accurate informations from images. The used techniques, mostly require a very precise calibration of cameras, either metric or non-metric cameras. This article presents the importance of a good determination of the intrinsic parameters in obtaining a high quality and accurate 3D model. In order to obtain the results, the 3D model of a sphere was created, using images acquired with the Canon PowerShot SX120 IS digital camera, whose intrinsic parameters were determined, using different calibration methods and objects. Finally, the 3D models obtained by using the same digital camera and different intrinsic parameters were compared with the model created with a precision of 10 μm based on the measurements made with the help of a micrometer. The differences between this models represent the influence of each calibration method on the accuracy of the final 3D model.
Keywords: accuracy, calibration, CMM,,digital images, 3D model
Entire article here
GNSS analysis for geodynamics application
Sorin Nistor, Aurelian-Stelian Buda, Norbert-Szabolcs Suba, Gabriela Cîmpan
Received: April 2015 / Accepted: June 2015 / Published: September 2015
Abstract
For geodynamics application we need to investigate the velocity uncertainties from GPS position time series. The only problem is that they are affected by time‐correlated noise. The proper time series analysis using GPS technique is that where we understand all stochastic effects that are captured using an appropriate noise technique. In time series analysis is very important to classify the source of noise: white noise, flicker noise, and random walk, because it is a tool for improving the accuracy.
The paper is studying the time correlated noise, estimates of spatial correlation, and multivariate power spectrum. For the processing technique we used spectral analysis and Maximum Likelihood Estimation. The best model for the noise characterizes of all three position components is a combination between white and flicker noise. Also we present the unmodelled periodic effect which is best captured in the harmonics function. The harmonics that are presented in the paper are: annual signal harmonics and GPS draconitic period harmonics.
Keywords: geodynamics application, time series, source of noise, annual signal harmonics, GPS draconitic period harmonics
Entire article here
Modern Means and Techniques for the Research upon the Analyse of the Subsidence Phenomenon
Maricel Palamariu, Ioan Voina
Received: April 2015 / Accepted: June 2015 / Published: September 2015
Abstract
This paper presents the monitoring methodology during the terrestrial surfaces dislocation as a result of the subterranean exploitation, using the most recent means and techniques.
The technologies are top innovations in the domain of modern methods in the engineering topography, with the purpose of rigorously monitor the risk and hazard phenomena, presenting a complex specific analyse for the process specific information are obtained, in an efficient and precise manner, from a quantitative, also from a qualitative point of view.
The means and techniques, the results, too, are described in a synthetic form, highlighting the importance and the applicability of the engineering topography to obtain the optimal solutions for solving engineering topography problems in correlation with the durable development strategy.
Keywords: interferometry, LIDAR, terrestrial laser scanning, subsidence
Entire article here
Study on the efficiency of using motorized levelling in vertical geodetic networks
Constantin Chirilă, Cristian Onu, Alexandra Celestina Tulan
Received: April 2015 / Accepted: June 2015 / Published: September 2015
Abstract
This paper proposes a general analysis of levelling works automation, which focuses on the precision and efficiency achieved by using motorized levelling, compared to the classic one. It presents the current state of research in the application of motorized levelling in some countries in Europe and the US, both in terms of equipment and methods of computation, in geometric and trigonometric levelling. The case study done on the road of the DJ 248B Horleşti, Rediu commune, Iaşi County, on a section of one kilometre, uses the motorized geometric levelling method and the traditional one to draw the necessary conclusions about measurement process optimization, as well as the extension of works in the national vertical geodetic network.
Keywords: Geometric levelling, trigonometric levelling, motorized levelling, precision, efficiency.
Entire article here
Hypothesis verification models in leveling geodetic networks
Alexandra Radu, Constantin Coșarcă (coordinator)
Received: April 2015 / Accepted: June 2015 / Published: September 2015
Abstract
Verifications by calculating the amount "Stress values" in the characteristic sections of the building are confronted with the results of tests on models or test sections. These are - currently - followed by observations made by means of measures installed both in body building and outside it. Hypothesis verification models are supplied by statistical tests. At measurements compensation are formulated several hypotheses. To validate or not the results obtained after compensation is necessary to verify such assumptions.
To detect possible deformations (displacement) occurring between two networks, observed at different times, it should be performed analysis only in the remaining common (identical) points in the interval Ti and Ti + 1. In principle, comparing the coordinates (ie altitudes / heights) of the network points determined at different stages and investigates whether they form or not congruent figures. The difference between the determined parameters for network points should be within into a "safety margin".
The safety margin is calculated according to the empirical standard deviation. If this does not fall within safe limits, the statistic test does not indicate anything other than that in the network have appeared deformations.
Keywords: Geometric leveling, accurate measurements, compensation, stability, displacements, statistical tests.
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