Tine Hren (Author), Klemen Kregar (Author), Aleš Marjetič (Author)

Abstract

Cerkveni zvoniki so bili zaradi svoje oblike in višje postavitve v preteklosti primerne orientacijske točke pri detajlni izmeri. Z razvojem metod satelitske izmere in predvsem uvedbo koordinatnega sistema D96/TM so počasi izgubljali pomen. Kljub temu so v primerjavi s talnimi trigonometričnimi točkami večinoma ostali nedotaknjeni. Kot takšni omogočajo določitev transformacijskih parametrov med starim in novim koordinatnim sistemom. Zato potrebujemo določitev njihovih položajev tudi v novem koordinatnem sistemu. V prispevku opisujemo postopek določitve položaja cerkvenega zvonika s terestričnim laserskim skeniranjem (TLS) na primeru obeh zvonikov Trnovske cerkve. Postopek vključuje določitev koordinat oslonilnih točk za georeferenciranje oblakov točk. To zahteva določitev geodetskega datuma s kombinacijo izmere GNSS in geometričnega nivelmana ter klasično izmero geodetske mreže z izravnavo proste mreže in uporabo postopka S-transformacije. Na podlagi georeferenciranih oblakov točk smo določili položaj trigonometrične točke zvonika z izravnavo parametrov krogle. Podatke filtriramo z algoritmom RANSAC, tako da imamo v izravnavi res le točke, ki pripadajo krogli. Rezultate smo primerjali s položaji, določenimi na podlagi klasične terestrične geodetske izmere.

Keywords

cerkveni zvonik;državni koordinatni sistem;geodetska mreža;terestrično lasersko skeniranje;georeferenciranje;oblak točk;izravnava po metodi najmanjših kvadratov;RANSAC;

Data

Language: Slovenian
Year of publishing:
Typology: 1.01 - Original Scientific Article
Organization: UL FGG - Faculty of Civil and Geodetic Engineering
UDC: 528.7:726
COBISS: 32284163 Link will open in a new window
ISSN: 0351-0271
Views: 162
Downloads: 71
Average score: 0 (0 votes)
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Other data

Secondary language: English
Secondary title: Determination of church belfry position using terrestrial laser scanning
Secondary abstract: In the past, church belfries, due to their shape and higher layout, often served as reference points in surveying. With the development of satellite based positioning methods and the establishment of the D96/TM coordinate system, they slowly lost their significance. Nevertheless, unlike ground trigonometric points, they have remained largely intact. As such, they enable the determination of transformation parameters between the old and the new coordinate systems. Therefore, we need to determine their positions in the new coordinate system. In this paper, we describe the process of determining the position of church belfries using terrestrial laser scanning (TLS) in the case of both belfries of the Trnovo church. The process involves determining coordinates of the tie points for georeferencing the point clouds, which requires the determination of the geodetic datum by a combination of GNSS measurement and geometric levelling, and the classical geodetic survey of the geodetic network with free-network adjustment and further use of the S-transformation. Based on the georeferenced point clouds, we determined the position of the trigonometric point by sphere parameters adjustment. The data is filtered using the RANSAC so that we only have points that belong to the sphere in the adjustment process. The results were compared with the positions determined based on the classical terrestrial geodetic survey.
Secondary keywords: church belfry;national coordinate system;geodetic network;terrestrial laser scanning;georeferencing;point cloud;least-squares adjustment;RANSAC;
Type (COBISS): Scientific work
Pages: str. 320-334
Volume: ǂLetn. ǂ64
Issue: ǂšt. ǂ3
Chronology: 2020
DOI: 10.15292/geodetski-vestnik.2020.03.320-334
ID: 13805869