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 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 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.
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.
Abstract. The Land Administration System (LAS) is of strategic importance to any country. Effective modern LAS should facilitate land management as an important instrument for the implementation of land policy contributing to comprehensive and sustainable land governance. The infrastructure needed to support increasingly complex requirements or urban space management based on three-dimensional register of rights would bring substantial improvement, especially for management of complex 3D situations. Modern cities are increasingly deploying different types of infrastructure under/on/above ground. The Republic of Croatia decided to establish the Register of Buildings, a transitional register combining data about buildings from existing registers towards the 3D cadastre. The transformation from 2D to 3D LAS should follow international standards, firstly the Land Administration Domain Model (LADM): ISO 19152:2012 but also other ISO and OGC standards. This study analyses the possible re-use of cadastral 3D datasets in smart urban governance procedures, the case of public purpose property valuation. To our opinion the establishment of a 3D LAS should facilitate and enable efficient and sustainable management of urban spaces.The prototype of 3D LAS, based on LADM conceptual model and its extensions, should enable efficient integration of 3D ownership rights register with the data from other domains - other key registers, taxation, and valuation data (property market data) and other sources of linked data. In this paper, the case study is used to assess the current practice of registration of buildings and their particular parts and analyse the differences between different implementation of 3D partitioned parts.
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