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1

Simulation of a cylindrical glass dome negative impact on a 360° field of view 2D laser scanner performance and a method for correction

Wojtanowski Jacek

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 3

art. no. e145566

EN

Although laser scanning ideas and hardware solutions are well-known to experts in the field, there is still a large area for optimization. Especially, if long-range and high-resolution scanning is considered, the smallest defects in optical quality should be perfected. On the other hand, the simplicity, reliability, and finally the cost of the solution plays an important role, too. In this paper, a very simple but efficient method of optical correction is presented. It is dedicated to laser scanners operating from inside cylindrical glass domes. Such covers normally introduce aberrations into both the laser beam and receiving optics. If these effects are uncorrected, the laser scanner performance is degraded both in terms of angular resolution and maximum range of operation. It may not be critical for short-range scanning applications; however, if more challenging concepts are considered, this issue becomes crucial. The proposed method does not require sophisticated optical solutions based on aspheric or freeform components, which are frequently used for similar purposes in imaging-through-dome correction but is based on a simple cylindrical refractive correction plate.

2

Selected aspects of data harmonization from terrestrial laser scanning

Zaczek-Peplinska Janina, Kowalska Maria Elżbieta, Nowak Edward

Archives of Civil Engineering

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2022

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Vol. 68, nr 3

429--445

EN

Periodic inventory and check surveys of the surfaces in engineering structures using terrestrial laser scanning require performing scans from many locations. The survey should be planned so as to obtain full coverage of the measured surface with a point cloud of appropriate density. Due to a variety of terrain obstacles in the close vicinity of the surveyed structure, structural and technical elements, as well as machinery and construction equipment (whose removal is impossible e.g. because of their role in the building and protection of the structure), it is often necessary to combine scans acquired from locations having different measurement geometry of the scene and performed in different lighting conditions. This makes it necessary to fill in blank spots with data of different spectral and geometric quality. This paper presents selected aspects of data harmonization in terrestrial laser scanning. The laser beam incidence angle and the scanning distance are assumed as parameters affecting the quality of the data. Based on the assumed minimum parameters for spectral data, an example of a harmonizing function for the concrete surface of a slurry wall was determined, and the methodology for determining its parameters was described. The presented solution for spectral data harmonization is based on the selection of reference fields representative of a given surface, and their classification with respect to selected geometric parameters of the registered point cloud. For geometric data, possible solutions to the harmonization problem have been analyzed, and criteria for point cloud reduction have been defined in order to obtain qualitatively consistent data. The presented results show that harmonization of point clouds obtained from different stations is necessary before their registration, in order to increase the reliability of analyses performed on the basis of check survey results in the assessment of the technical condition of a surface, its deformation, cracks and scratches.

PL

Okresowe pomiary inwentaryzacyjne i kontrolne powierzchni obiektów inżynierskich metodą naziemnego skaningu laserowego wymagają wykonania skanowania z wielu stanowisk instrumentu. Pomiar obiektu powinien być tak zaplanowany, aby uzyskać pełne pokrycie mierzonej powierzchni chmurą punktów o odpowiedniej gęstości. Ze względu na znajdujące się w bliskim otoczeniu mierzonego obiektu przeszkody terenowe, elementy konstrukcyjne i techniczne a także maszyny i urządzenia budowlane, których usunięcie na czas wykonywania pomiaru jest niemożliwe np. służące realizacji i zabezpieczeniu obiektu często niezbędne jest łączenie skanów pozyskanych ze stanowisk o różnej geometrii sceny pomiarowej i wykonanych w różnych warunkach oświetlenia. Skutkuje to koniecznością uzupełniania martwych (pustych) pól danymi o różnej jakości spektralnej i geometrycznej. W artykule zaprezentowano wybrane aspekty harmonizacji danych z naziemnego skaningu laserowego. Jako parametry wpływające na jakość danych przyjęto kąt padania wiązki laserowej oraz odległość skanowania. W oparciu o przyjęte minimalne parametry dla danych spektralnych wyznaczono przykładową funkcję harmonizującą dla betonowej powierzchni ściany szczelinowej oraz opisano metodykę wyznaczania jej parametrów. Prezentowane rozwiązanie dla harmonizacji danych spektralnych opiera się na wyborze reprezentatywnych dla danej powierzchni pól referencyjnych i ich klasyfikacji w odniesieniu do wybranych parametrów geometrycznych zarejestrowanej chmury punktów. Dla danych geometrycznych przeanalizowano możliwe rozwiązania problemu harmonizacji oraz określono kryteria ograniczania chmur punktów w celu uzyskiwania spójnych jakościowo danych. Na podstawie zaprezentowanych wyników wykazano, że harmonizacja pojedynczych chmur punktów pozyskanych z różnych stanowisk jest konieczna przed ich wspólną rejestracją (register points clouds) w celu podniesienia wiarygodności analiz wykonywanych na podstawie wyników pomiarów kontrolnych do oceny stanu technicznego powierzchni, jej deformacji oraz spękań i rys.

3

Zastosowanie skanowania laserowego 3D w inwentaryzacji budynków zabytkowych

Markowski Hubert

Builder

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2020

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R.24, nr 6

50--53

PL

Dynamiczny rozwój nowoczesnych technologii pozwala na projektowanie urządzeń, które zmieniają dotychczasowe podejście do projektowania i inwentaryzacji budynków. Artykuł dotyczy zastosowania skaningu laserowego 3D w inwentaryzacji budynków zabytkowych. Na wstępie przedstawiono syntetyczny opis technologii skaningu laserowego. Następnie, na przykładzie zabytkowego kompleksu budynków zlokalizowanych na Starym Mieście w Warszawie, opisano i przeanalizowano zasady przeprowadzania inwentaryzacji, obróbki wykonanych skanów oraz zasad przygotowywania dokumentacji płaskiej z wykorzystaniem pozyskanych informacji 3D. W artykule wyjaśniono także, dlaczego wykorzystanie wspomnianej technologii jest szczególnie ważne w przypadku inwentaryzacji budynków zabytkowych. Całość jest zakończona wnioskami wynikającymi z wad i zalet zastosowania skaningu laserowego, a także bibliografią wykorzystanych źródeł.

EN

The dynamic development of modern technologies allows the design of devices that change the current approach to the design and inventory of buildings. The article concerns the use of Terrestrial Laser Scanning 3D in the inventory of historic buildings. At the beginning a synthetic description of TLS 3D is presented. The rest of the article presents an example of an inventory of the historic building complex located in the Old Town in Warsaw, the rules for carrying it out, processing scans made and finally the rules for preparing flat documentation using the obtained 3d information. In the article we will also find out why the use of this technology is particularly important in the case of an inventory of historic buildings. The whole article is concluded with conclusions resulting from the advantages and disadvantages of using laser scanning and a bibliography of sources used.

4

Implementation of GPR and TLS data for the assessment of the bridge slab geometry and reinforcement

Cafiso S., Di Graziano A., Goulias D., Mangiameli M., Mussumeci G.

Archives of Civil Engineering

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2020

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Vol. 66, nr 1

297--308

EN

This paper presents a suggested approach for forensic investigation of bridge decks in which Ground penetrating radar (GPR) consisting of two antennas is used to assess the current conditions. The methodology was tested on a bridge deck in central Sicily. The acquired data were analyzed for identifying the asphalt overlay thickness, concrete cover depth and deck thickness and location of the rebar reinforcement. In the proposed approach for assessing bridge deck conditions the GPR survey was complemented with (i) a site investigation on layer thicknesses for calibration/verification purposes of the GPR response and (ii) a Terrestrial Laser Scanning system (TLS) to verify the bridge design slab curvature. The study shows that this methodology has significant merits on accurately assessing such bridge deck components when bridge design records are non-existing, and by using non-invasive methods such as laser scanning and GPR. The great advantage provided by the TLS technique is the possibility to obtain a 3D output model of the scanned element with the accuracy of the best topographic instruments in order to complement GPR data surveys for bridge inspection.

5

Metodyka oceny stanu powierzchni betonowej budowli piętrzącej na podstawie analizy spektralnej wyników naziemnego skanowania laserowego

Zaczek-Peplinska J.

Prace Naukowe Politechniki Warszawskiej. Geodezja

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2018

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z. 57

3--177

6

Laser scanning in engineering surveying : methods of measurement and modeling of structures

Lenda G., Uznański A., Strach M., Lewińska P.

Reports on Geodesy and Geoinformatics

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2016

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Vol. 100

109--130

EN

The study is devoted to the uses of laser scanning in the field of engineering surveying. It is currently one of the main trends of research which is developed at the Department of Engineering Surveying and Civil Engineering at the Faculty of Mining Surveying and Environmental Engineering of AGH University of Science and Technology in Krakow. They mainly relate to the issues associated with tower and shell structures, infrastructure of rail routes, or development of digital elevation models for a wide range of applications. These issues often require the use of a variety of scanning techniques (stationary, mobile), but the differences also regard the planning of measurement stations and methods of merging point clouds. Significant differences appear during the analysis of point clouds, especially when modeling objects. Analysis of the selected parameters is already possible basing on ad hoc measurements carried out on a point cloud. However, only the construction of three-dimensional models provides complete information about the shape of structures, allows to perform the analysis in any place and reduces the amount of the stored data. Some structures can be modeled in the form of simple axes, sections, or solids, for others it becomes necessary to create sophisticated models of surfaces, depicting local deformations. The examples selected for the study allow to assess the scope of measurement and office work for a variety of uses related to the issue set forth in the title of this study. Additionally, the latest, forward-looking technology was presented - laser scanning performed from Unmanned Aerial Vehicles (drones). Currently, it is basically in the prototype phase, but it might be expected to make a significant progress in numerous applications in the field of engineering surveying.

7

Complex geodetic research in Ukrainian Antarctic station "Academician Vernadsky" (years 2002-2005, 2013-2014)

Tretyak K., Hlotov V., Holubinka Y., Marusazh K.

Reports on Geodesy and Geoinformatics

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2016

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Vol. 100

149--163

EN

In this paper is given an information about complex geodetic research in Ukrainian Antarctic station “Academician Vernadsky”. Research were carried by Lviv polytechnic scientists, during Antarctic expeditions in years 2002 - 2005, 2013, 2014. Main objectives of the studies were: (a) study of the islands glaciers surface volumes changes in Antarctic archipelago and Antarctic Peninsula using terestrial laser scaning and digital terrestrial stereophotogrammetry survey; (b) investigation of Penola strain tectonic fault, using the results of precise GNSS observations.

8

The attempt to use levelling rods for testing metric properties of surveying instruments, which are used for reflectorless distance measurements

Świerczyńska E., Kołakowska M.

Reports on Geodesy and Geoinformatics

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2014

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Vol. 96

38--54

EN

This paper presents results of two experimental cycles of measurements performed with the use of the terrestrial laser scanner Z+F IMAGER 5006h and the reflectorless tacheometer Leica TPS 1202. These tests aimed at determination of metric properties of surveying instruments, which are used for reflectorless distance measurements and which are often applied to project the geometry of objects. In the course of research works issues influencing the reflection of a laser beam by the measured surface, as well as their influence on the data quality. In order to analyse metric properties of applied instruments, levelling rods were used as test fields of geometrically specified division. It was stated basing on the performed analyses, that the influence of the incidental angle of a laser beam on the accuracy of reflectorless measurements is included within the limits of the error of distance measurements of a given instrument. However, the uniform trend of increasing differences between measured values and the nominal value may be noticed, together with the increase of the incidental angle of the axis of collimation on the measured surface of the test field.

9

Development of large concrete object geometrical model based on terrestrial laser scanning

Zaczek-Peplinska J., Popielski P., Kasprzak A., Wójcik P.

Reports on Geodesy and Geoinformatics

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2014

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Vol. 97

91--102

EN

The paper presents control periodic measurements of movements and survey of concrete dam on Dunajec River in Rożnów, Poland. Topographical survey was conducted using laser scanning technique. The goal of survey was data collection and creation of a geometrical model. Acquired cross- and horizontal sections were utilised to create a numerical model of object behaviour at various load depending of changing level of water in reservoir. Modelling was accomplished using finite elements technique. During the project an assessment was conducted to terrestrial laser scanning techniques for such type of research of large hydrotechnical objects such as gravitational water dams. Developed model can be used to define deformations and displacement prognosis.

10

Volumes determination in terms of various data density and surface diversity

Sokol S., Bajtala M., Lipták M., Brunčák P.

Journal of Sustainable Mining

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2014

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Vol. 13, iss. 4

23--27

EN

Purpose The aim of this paper is to assess the impact of input data density and diversity on surfaces obtained using the terrestrial laser scanning (TLS) method for creating digital elevation model (DEM). For this we can use several approaches, while we have chosen an intermediary parameter – volume calculation, which is in practice the most frequently requested requirement from surveyors. Methods Precise terrestrial measurement and terrestrial laser scanning were used to ensure that detailed knowledge about the surface and volumes of two piles of earth and a stone pit in comparison with theoretical defined surfaces was obtained. Results Mathematically defined surfaces generally have smooth shapes, and thus the effect of different density on the input data is less apparent in the final comparison of volumes. In our case the results for most of the different interpolation methods and the different density of the input data was less than 0.5%. From the experimental measurements of the two earth bodies and the quarry, which have an irregular shape with unsmooth surfaces, we can only test the relative precision of the calculated volumes to the data with the highest density. Experimental measurements in the area of the quarry, where the scanned surface was uneven and considerably different in height, confirmed the assumption that a vastly irregular surface should exhibit more significant variations than a smooth surface, but for the nearest neighbour method relative errors under 1% were achieved. Practical implications According to the results from the analysis above, the lower density of input data we have, the lower the precision of calculating volumes we can assume, but it is interesting that we did not achieved significantly worse results with strongly irregular surfaces compared to a less irregular surface. Originality/ value The input values for the analysis of theoretically defined surfaces were obtained by the calculation of integral calculus and earth-moving bodies and quarry from an experimental measurement terrestrial laser scanning method and were used in Slovakia for the first time.

11

Monitoring technical conditions of engineering structures using the terrestrial laser scanning technology

Zaczek-Peplinska J., Pasik M., Adamek A., Adamek A., Kołakowska M., Łapiński S.

Reports on Geodesy and Geoinformatics

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2013

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Vol. 95

1--10

EN

The laser scanning technology offers quite new possibilities in the field of the existing monitoring of engineering structures. The basic advantage of the laser scanning technology is huge amount of measuring observations and practically complete geometric and spectral information about the measured structures, which may be required within the short time. In the context of detection of threatens related to deformations and displacements of building structures, the surface - quasi-continuous distribution of measuring points is one of the most important factors. which ensure the possibility to perform correct evaluation of safety conditions of investigated structures. The proposed technological solution offers a series of new possibilities and the resulting methodology of determination of deformations and displacements of various structures, will considerably increase the scope of possible works and analyses. This will also create the new segment of data, which will result in delivery of additional information concerning conditions of the structure to experts from various fields, such as, among others, civil engineering, construction or geotechnique, who monitor the given structure.