Carl Ritter von Ghega was proclaimed 2018 Surveyor of the Year on 21 March 2018. In this paper, we explore how this Austrian of Albanian extraction, born in Venice, played an important role in ...geodesy and the surveying profession and the honours he got up to the present day. We investigate his background and details of his professional path, education and most important contributions in the areas of surveying and
engineering at large. We describe his most significant achievement, that is, the Semmering Railway, which was dismissed at the time as impossible to achieve. In 1998, the Semmering Railway was inscribed in the UNESCO World Heritage List. Apart from this project, which left a great impression on the engineering profession, von Ghega also developed
the Borovnica Viaduct built in the mid-19th century in Slovenia.
Carl Ritter von Ghega 21. ožujka 2018. proglašen je geodetom godine 2018. U ovome se radu elaborira čime je Austrijanac albanskih korijena, rođen u Veneciji, zadužio geodete i geodetsku struku te prema tome koje su mu sve počasti do danas dodijeljene. Istražuje se njegovo porijeklo te detaljno njegov profesionalni put, obrazovanje i najznačajniji doprinosi u području geodezije i inženjerstva uopće. Opisuje se njegovo najznačajnije postignuće – tzv. projekt Semerinške željeznice za koji se
u to vrijeme vjerovalo da ga nije moguće realizirati. Semerinška je željeznica 1998. uvrštena na UNESCO-ov popis mjesta svjetske baštine. Osim projekta Semerinške željeznice kojim je zadužio inženjersku struku,
elaborira se i vijadukt Borovnica koji je sagrađen sredinom 19. stoljeća u dolini Borovnica u Sloveniji.
The role and importance of geodesists in the planning and building of civil engineering constructions are well known. However, the importance and benefits of collected data during maintenance in ...exploitation have arisen in the last thirty years due primarily to the development of Global Positioning Systems (GPS) and Global Navigation Satellite System (GNSS) instruments, sensors and systems, which can receive signals from multiple GPS systems. In the last fifteen years, the development of Terrestrial Laser Scanners (TLS) and Image-Assisted Total Stations (IATS) has enabled much wider integration of these types of geodetic instruments with their sensors into monitoring systems for the displacement and deformation monitoring of structures, as well as for regular structure inspections. While GNSS sensors have certain limitations regarding their accuracy, their suitability in monitoring systems, and the need for a clean horizon, IATS do not have these limitations. The latest development of Total Stations (TS) called IATS is a theodolite that consists of a Robotic Total Station (RTS) with integrated image sensors. Today, IATS can be used for structural and geo-monitoring, i.e., for the determination of static and dynamic displacements and deformations, as well as for the determination of civil engineering structures’ natural frequencies. In this way, IATS can provide essential information about the current condition of structures. However, like all instruments and sensors, they have their advantages and disadvantages. IATS’s biggest advantage is their high level of accuracy and precision and the fact that they do not need to be set up on the structure, while their biggest disadvantage is that they are expensive. In this paper, the developed low-cost IATS prototype, which consists of an RTS Leica TPS1201 instrument and GoPro Hero5 camera, is presented. At first, the IATS prototype was tested in the laboratory where simulated dynamic displacements were determined. After the experiment, the IATS prototype was used in the field for the purpose of static and dynamic load testing of the railway bridge Kloštar, after its reconstruction according to HRN ISO NORM U.M1.046—Testing of bridges by load test. In this article, the determination of bridge dynamic displacements and results of the computation of natural frequencies using FFT from the measurement data obtained by means of IATS are presented. During the load testing of the bridge, the frequencies were also determined by accelerometers, and these data were used as a reference for the assessment of IATS accuracy and suitability for dynamic testing. From the conducted measurements, we successfully determined natural bridge frequencies as they match the results gained by accelerometers.
A novel method for structural health monitoring (SHM) by using RGB+D data has been recently proposed. RGB+D data are created by fusing image and laser scan data, where the D channel represents the ...distance, interpolated from laser scanner data. RGB channel represents image data obtained by an image sensor integrated in robotic total station (RTS) telescope, or on top of the telescope i.e., image assisted total station (IATS). Images can also be obtained by conventional cameras, or cameras integrated with RTS (different kind of prototypes). RGB+D image combines the advantages of the two measuring methods. Laser scans are used for distance changes in the line of sight and image data are used for displacements determination in two axes perpendicular to the viewing direction of the camera. Image feature detection and matching algorithms detect and match discrete points within RGB+D images obtained from different epochs. These way 3D coordinates of the points can be easily calculated from RGB+D images. In this study, the implementation of this method was proposed for measuring displacements and monitoring the behavior of structural elements under constant load in field conditions. For the precision analysis of the proposed method, displacements obtained from a numerical model in combination with measurements from a high precision linear variable differential transformer (LVDT) sensor was used as a reference for the analysis of determined displacements from RGB+D images. Based on the achieved results, we calculated that in this study, the precision of the image matching and fusion part of the RGB+D is ±1 mm while using the ORB algorithm. The ORB algorithm was determined as the optimal algorithm for this study, with good computing performance, lowest processing times and the highest number of usable features detected. The calculated achievable precision for determining height displacement while monitoring the behavior of structural element wooden beam under different loads is ±2.7 mm.
This paper describes the non-contact vibration monitoring of prestressed reinforced concrete railway sleepers. The monitoring was carried out using physical measuring equipment consisting of a ...seismograph and geophones, a robotic total station (RTS) and scanning laser Doppler vibrometry (SLDV) equipment. Measurements of the dynamic response of sleepers to the dynamic loading induced by the running of train sets provides data that give an insight into the actual state of the sleeper structure at the moment when it is most stressed. The main objective of the study was to identify the most appropriate form of monitoring to monitor events related to the occurrence of cracks in the rail sill, which can also be caused by the impact of vibration. As is well-known, monitoring the dynamic response of railway sleepers is very important for the sustainable management and maintenance of railway lines. The vibration analysis was carried out in the field on the Ormož–Ptuj section of the railway line, in Velika Nedelja and in the laboratory of the UM FGPA, where the vibration was simulated using a hydraulic kit with a static and pulsed force of 100 kN. Several cycles of measurement were carried out and the results were compared with the results of the field monitoring. The vibration parameters measured for the concrete sleepers are necessary to develop a realistic dynamic model of the railway line, which will be able to predict its response to impact loads and the possible occurrence of damage, as has recently been observed for concrete sleepers in several European Union countries.
A systematic approach to the establishment of the Franciscan Cadastre, which has been performed in most Central European countries, has resulted in the following documents: cadastral maps, cadastral ...municipality boundary demarcation records, lists of land parcels, lists of building parcels and lists of possessors. The documentation, which is stored in various archives, is digitized and made available to users through catalogs. The availability of documentation was examined in this study using three services in the catalogs—discovery, view and download—of which the largest percentage of documents is available through the discovery service. Documents that are available through the discovery service are described by the metadata standards. In this study, we examined the applicability of geographic information metadata standards and metadata standards to archival documentation in catalogs in which cadastral documentation was found. We determined a lack of application of geoinformation metadata standards, as it was a cadastral dataset, which represented one of the fundamental spatial datasets. The semantic mapping of elements between the applied standards in the catalogs and the geoinformation metadata standard (ISO 19115) showed that it was possible to apply the ISO 19115 standard to documents resulting from the establishment of the cadastre.
Theodolites are fundamental geodetic measuring instruments for all practical geodetic tasks, as well as for experimental geodetic scientific purposes. Their development has a long history. Photo and ...video theodolites represent the advanced development of classic theodolites. Development started in 19th century, but only in the last 15 years has commercial application been achieved in the geodetic profession. The latest development, called image-assisted total stations (IATS), is a theodolite which consists of a classic robotic total station (RTS) with integrated image sensors. It was introduced in the early 2000s. With the development of theodolites, their application became much wider; today, they can be used for structural and geo-monitoring, i.e., for the determination of static and dynamic displacements and deformations of civil engineering structures such as bridges, dams, wind turbines, and high buildings, as well as natural structures, such as mountain slopes. They can be implemented in geodetic monitoring systems, which are an integral part of engineering structural diagnosis, and they provide essential information about the current condition of the structure. This paper describes the technological development of photo and video theodolites divided into phases according to the main innovations in their development. The application of modern video theodolites (i.e., IATS) is presented through several experimental studies that were performed. The procedure of conducting measurements with this kind of instrument, as well as the analysis of acquired data and achieved results, is elaborated. Lastly, the authors conclude, according to the achieved results, that IATS can today be used for determination of quasi-static and dynamic displacements with small and high amplitudes.
The possibility of using unmanned aircraft systems (UAS) for cadastral survey purposes was investigated in this research. A study site consisting of 26 ground control points (GCP) and checkpoints ...(CP) was established. The study site was first measured by the classical methods of geodetic surveying, i.e., by the polar method using a total station. After that, all points were additionally measured by the Global Navigation Satellite System (GNSS) Real-Time Kinematic (RTK) method. The GNSS RTK method was used to determine the coordinates of all points in the official map projection of Croatia, HTRS96/TM, while the polar method was used to increase the positional “strength” of points in all directions, i.e., to improve the relative accuracy between them. Using UASs with different image sensor characteristics, the study site was measured by an aerial photogrammetry method at different flight heights with the purpose of obtaining a high-quality digital orthophoto plan (DOF). The absolute orientation of the model was performed using the external orientation data of each digital image based on GNSS and Inertial Measurement Unit (IMU) UAS’s sensors, as well as using GCPs. Achieved precision of obtained DOF, as well as accuracy analysis of aerial photogrammetry was performed by considering the adjusted survey data collected by classical and GNSS RTK methods as true values and comparing them with the coordinates obtained by the aerial photogrammetry method from DOFs. Based on the achieved results and conclusions obtained from the study site, the second field test was performed above a small settlement which served as an area for cadastral survey using the UAS and GNSS RTK method. Again, precision and accuracy were determined, based on which we derived recommendations and conclusions for using UASs for cadastral survey purposes.
Abstract
GNSS has limitations or cannot be applied in specific environments with poor geometry like city streets, tunnels, bridges, quarries, mines, ports or in indoor environment in general. In 2003 ...Locata Corporation from Australia began with the development of a new, completely independent technology called Locata, which was designed to overcome the limitations of GNSS. Within the project “Wearable Outdoor Augmented Reality System for the Enrichment of Touristic Content” Locata system was implemented for the first time in the Republic of Croatia. The quality of the established LocataNet network and the quality of the Locata positioning are presented in this paper as the basis for future research of possibilities to use Locata in displacement measurement. Achieved positioning precision is in a range of few mm in the horizontal direction and up to a couple of cm in the vertical direction. Although high level of precision is achieved, the accuracy, i. e. the errors of positioning solutions are up to several cm. Among other things, the research presented in this paper is focused on the reasons for achieved lower accuracy that probably have their roots in the instability of the LocataLite transmitting antennas in the established LocataNet. They namely affect the estimated float ambiguities of carrier phase measurements. Potential of relative positioning is another topic of this research, because it could allow the fixing of ambiguities to integer values and result in increase of accuracy and precision of positioning.
For the most common geodetic tasks such as surveying, staking out and monitoring, GNSS RTK method has in many cases been limited by its measuring quality. Combining laser system with GNSS RTK system ...enables the increase of vertical accuracy of measurement to a millimetre level. Testing the above mentioned systems for height determination will be presented in this paper. Since December 2008 CROatian POsitioning System (CROPOS) has been operational. GPS RTK system combined with laser system has been tested with CROPOS service, because more and more users are using this system in every day geodetic tasks. Testing the vertical accuracy of measuring modes has been done on the calibration baseline of the Faculty of Geodesy in Zagreb. Heights were determined by four different measuring modes; GPS RTK method in combination with laser system, GPS RTK method in combination with laser system linked with CROPOS service (VPPS - Very Precise Positioning Service), GPS RTK method and GPS RTK method linked with CROPOS service (VPPS). The authors of the paper will try to examine whether it is possible to achieve higher accuracy of vertical component when GPS RTK system is combined with laser system. Finally, the advantages, possible disadvantages, and vertical quality comparison of all measuring modes will be shown in this paper
5th International Conference on Engineering Surveying was held on the Brijuni Islands from 22 to 24 September 2011. The conference organizers were the Department of Surveying Faculty of Civil ...Engineering at the Slovak University of Technology in Bratislava and the Institute for Applied Geodesy at the Faculty of Geodesy, University of Zagreb, with the FIG Commission 6. The conference was held under the patronage of the Ministry of Environmental Protection, Physical Planning and Construction of the Republic of Croatia. The conference took place in the Castrum Congress Hall of Hotel Neptun-Istra. The official language of the conference was English. The conference was attended by 70 representatives from Croatia, Slovenia, Serbia, Kosovo, Austria, Germany, Hungary, Greece, Czech Republic and Slovakia, and a total of 40 papers were presented.
PDF
