Article

The contribution of laser scanning technology in the estimation of ancient Greek monuments' deformations

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Terrestrial laser scanning technology is nowadays more and more used for the documentation of cultural heritage monuments. The thorough exploitation of the main advantage of terrestrial laser scanners (TLS) that is the acquisition of extremely dense discrete points in a relatively small time period leads to detailed 3D representation of the monument, overcoming possible difficulties such as limited accessibility. Most often, this 3D representation is used for the monument's documentation as well as for virtual tours in, out or around it. This detailed documentation can be used for one more purpose: the estimation of the deformation that its elements have experienced through the centuries and, following, the monument's restoration, provided that, its' initial, constructional geometry is known. In this paper, research towards this goal is presented, dealing with the estimation of the deformations of a column of the ancient temple of Zeus in Nemea Greece using TLS technology. This column is standing erect since the temple's construction in 330 BC and it has been subject to serious deformations because of various causes.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Nowadays, a laser scanning and photogrammetry, as surveying and three-dimensional (3D) modelling techniques, are extremely important for documentation of cultural heritage (Guarnieri et al. 2013). In all the branches of cultural heritage field the 3D survey is an essential support for a number of activities: the object documentation, different kinds of analysis (statistical analysis, historical reconstructions, etc.), the communication and promotion of the sites, deformation estimation, adoption of BIM (Building Information Modelling) etc. (Aicardi et al. 2018, Georgopoulos et al. 2016, Rodríguez-Moreno et al. 2016. Aside from providing a record for future generations, photogrammetry can aid in the more practical quantitative planning of conservation and restoration. ...
Article
Full-text available
This paper describes the preparation of documentation of a part of the cultural and historical heritage of Bosnia and Herzegovina, the famous chapel on the Orthodox cemetery ‘Holy Archangels George and Gabriel’ located in Saraje�vo, by the method of UAV photogrammetry. Two aircrafts (semi-professional and amateur) DJI Phantom 4 Pro and DJI Mavic Pro were used, and 3D models were made based on the photos taken. The quality of chapel 3D models was evaluated by estimating the geometrical accuracy, with different aspects and combinations. The obtained absolute 3D accuracy of the high-resolution model is 14 mm, while the relative accuracy is 9 mm.
... Both ToF and PS scanners are extensively used for deformation monitoring of historic structures. The geometric deformations are estimated by comparing measured point clouds with an idealized shape [65][66][67][68][69][70][71][72][73] or by performing multitemporal measurements [74][75][76][77]. Furthermore, laser scanning appears to be particularly suitable for obtaining the necessary geometric data to generate numerical models for structural health analysis, in terms of rapidity and spatial resolution [78][79][80][81][82]. ...
Article
Full-text available
Built cultural heritage is under constant threat due to environmental pressures, anthropogenic damages, and interventions. Understanding the preservation state of monuments and historical structures, and the factors that alter their architectural and structural characteristics through time, is crucial for ensuring their protection. Therefore, inspection and monitoring techniques are essential for heritage preservation, as they enable knowledge about the altering factors that put built cultural heritage at risk, by recording their immediate effects on monuments and historic structures. Nondestructive evaluations with close-range sensing techniques play a crucial role in monitoring. However, data recorded by different sensors are frequently processed separately, which hinders integrated use, visualization, and interpretation. This article’s aim is twofold: i) to present an overview of close-range sensing techniques frequently applied to evaluate built heritage conditions, and ii) to review the progress made regarding the fusion of multi-sensor data recorded by them. Particular emphasis is given to the integration of data from metric surveying and from recording techniques that are traditionally non-metric. The article attempts to shed light on the problems of the individual and integrated use of image-based modeling, laser scanning, thermography, multispectral imaging, ground penetrating radar, and ultrasonic testing, giving heritage practitioners a point of reference for the successful implementation of multidisciplinary approaches for built cultural heritage scientific investigations.
... Actualmente existen muchos tipos de escáneres 3D con diferentes características atendiendo al rango de distancia medida, la tecnología usada o la exactitud conseguida (Georgopoulos et al., 2016). El uso de los escáneres 3D en el estudio y conservación del patrimonio cultural es un hecho ya consolidado con aplicaciones sobre objetos y sitios arqueológicos de diferentes tamaños, características y épocas (Fehér, 2013;Neiß et al., 2016;Rodríguez-Gonzálvez et al., 2015). ...
... Using 3-D model, damaged part and details of the structure were easily detected and geometrically identified. The interesting method of estimation the deformations in heritage structure by TLS was presented in [13]. The column of an ancient Temple in Greece, which was built in 330 B.C., was chosen for the study. ...
Article
Full-text available
Historical structures, buildings, bridges, and walls are very sensitive to deformations which can be caused by many factors, such as winds, heavy rains, extreme temperature variations, ground and soil settlements, tectonic loadings, and others. The mapping of 3-D deformation maps of building provides an opportunity not only to understand the structural changes, but also to detect zones with a potential risk of damage. The high spatial resolution of terrestrial laser scanning (TLS) technology allows monitoring historical buildings with millimeter accuracy. Two towers of Istanbul Land Walls were surveyed three times with the 5-month time interval. The accurate deviation maps were obtained from TLS’s data by comparing epochs. Between first two campaigns, there happened an earthquake with the magnitude of Mw 5.7 with the epicenter of approximately 60kmfromthe study area. The findings and outputs of this article indicate that earthquake had a great impact on the monitored structures and deformations were found up to 15 mm for the tower I and up to 20 mm for the tower II.
... A scanner is a device that digitalises objects so that they are available in virtual format via point cloud model and image photographic texture recording. A wide range of scanners is available, and the applications in the field of cultural heritage are constantly growing, making it possible to create a faithful model of reality [Georgopoulos et al. 2016;Di Angelo et al. 2018]. For example, some structured light 3D scanners provide resolutions of between from 0.1 mm to 0.5 mm (Fig. 5 a). ...
Conference Paper
Full-text available
Nowadays, there are several virtual tools to document the archaeological objects for the general public. The use of knowledge network makes it possible to disseminate the content and provide access to the creation and the distribution of other types of image which were previously restricted to only a few people. In this way, the analogue image has been replaced with its digital version, assuming that it is the best approach to achieve a more comprehensive dissemination of information, without asking if the archaeological context has been marginalised. In general, virtual technology is being used to surprise, without really attempting to help explain the object, with all its historical memory. The purpose of this approach is to compare these working methods from both analogue and virtual points of view, considering problems such as the cost of modelling, the amount of time required, or the need for an expert user to manage the virtual tools. The virtual documentation will include all of the interactive information of the object, managed from a Wiki 1 , including bibliography, links to archaeological database, high resolution photography 2 and 3D models of the archaeological objects obtained from both 3D scanner and digital photography using the Image-Based Modelling system 3. In conclusion, it is considered that the traditional analogue information from these objects can and should be included in this virtual proposal.
... No statistics are available, but there is evidence of frequent deviations from the ideal cases. For example, a laser scan analysis of one of the surviving columns of the temple of Nemea indicates that its vertical axis is not vertical, as is derived from observations with the naked eye, but it has a bowtype shape with maximum deflection of several centimeters (Georgopoulos et al. 2016). Evidence from Fig. 7 in fact indicates that the platforms of certain temples (Basai, Ramnous, etc.) are not horizontal and rigid. ...
Article
Full-text available
Structural analyses indicate that monumental articulated ancient Greek and Roman (MAGR) columns and temples have a very particular seismic response, differing from rigid structures (made with mortar); tall columns in particular, have an excellent seismic performance, favoring anthropogenic effects as causes of their destruction. Archeoseismological studies, on the other hand, provide evidence of seismic damage in MAGR structures. To investigate this apparent conflict, we analyzed the conditions and limitations of structural models, as well as historical and archeological evidence of response of such structures to natural and anthropogenic effects. In addition, we examined two groups of MAGR structures: first, structures damaged or destroyed by known causes, including earthquakes and wind; second, structures damaged by unknown causes, based on comparative damage analyses with emphasis on geotechnical (soil dynamics) effects. This analysis indicates that reports of deliberate destructions of MAGR structures are exaggerated, and in addition, (i) these structures seem safe against earthquakes only if structurally healthy, concerning both their superstructure and foundations; this condition is not always satisfied, and hence, no controversy exists between structural engineering and archeoseismological approaches; (ii) their seismic response is sensitive to small changes of the source- and site-specific parameters; and (iii) no deterministic evidence of absence or of occurrence of critical earthquakes can be derived from their survival or damage, because the latter reflects superimposition of natural and anthropogenic destructive effects, some with apparently similar outcomes, and rarely only single event destructions. These results are important for palaeoseismology (paleoseismology), seismic risk assessment, archaeology (archeology), and restoration of ancient monuments.
... A scanner is a device that digitalises objects so that they are available in virtual format via point cloud model and image photographic texture recording. A wide range of scanners is available, and the applications in the field of cultural heritage are constantly growing, making it possible to create a faithful model of reality [Georgopoulos et al. 2016;Di Angelo et al. 2018]. For example, some structured light 3D scanners provide resolutions of between from 0.1 mm to 0.5 mm (Fig. 5 a). ...
Conference Paper
Full-text available
Nowadays, there are several virtual tools to document the archaeological objects for the general public. The use of knowledge network makes it possible to disseminate the content and provide access to the creation and the distribution of other types of image which were previously restricted to only a few people. In this way, the analogue image has been replaced with its digital version, assuming that it is the best approach to achieve a more comprehensive dissemination of information, without asking if the archaeological context has been marginalised. In general, virtual technology is being used to surprise, without really attempting to help explain the object, with all its historical memory. The purpose of this approach is to compare these working methods from both analogue and virtual points of view, considering problems such as the cost of modelling, the amount of time required, or the need for an expert user to manage the virtual tools. The virtual documentation will include all of the interactive information of the object, managed from a Wiki 1 , including bibliography, links to archaeological database, high resolution photography 2 and 3D models of the archaeological objects obtained from both 3D scanner and digital photography using the Image-Based Modelling system 3. In conclusion, it is considered that the traditional analogue information from these objects can and should be included in this virtual proposal.
... One of the first promising laboratory studies on the implementation of TLS in displacement and deformation measurements demonstrated that, with favourable environmental conditions, TLS measurement can be used to measure the vertical displacement down to ±0.29 mm [4]. The application of TLS in displacement and deformation measurement has been widely investigated regarding both geometry [5][6] and spectral analyses of the intensity of the reflected beam [7][8]. The papers have been partially, extensively summarised and organised by researchers from the University of Nottingham Ningbo [9]. ...
Article
Full-text available
Terrestrial laser scanning (TLS) technology has become increasingly popular in investigating displacement and deformation of natural and anthropogenic objects. Regardless of the accuracy of deformation identification, TLS provides remote comprehensive information about the measured object in a short time. These features of TLS were why TLS measurement was used for a static load test of an old, steel railway bridge. The results of the measurement using the Z+F Imager 5010 scanner and traditional surveying methods (for improved georeferencing) were compared to results of precise reflectorless tacheometry and precise levelling. The analyses involved various procedures for the determination of displacement from 3D data (black & white target analysis, point cloud analysis, and mesh surface analysis) and the need to pre-process the 3D data was considered (georeferencing, automated filtering). The results demonstrate that TLS measurement can identify vertical displacement in line with the results of traditional measurements down to ±1 mm.
... Usually, a 3D model can be generated by means of 3D scanners. These devices are already known for their accurate three-dimensional measurements (Georgopoulos et al. 2016), being an alternative to classical measurement methods. 3D laser scanning is generally expensive and requires an expert user. ...
Article
The image-based modelling systems create 3D models of objects using a set of overlapping photographs. Several applications are available that do not require a user expert or expensive equipment. In this paper, four free systems were applied in two cases: ReMake, which is a freemium software, CMP Web Service and Arc 3D, which are free web services, and Visual SfM, which is a free software. The purpose of this study is to evaluate the applications that support topographical measurements and to assess the potential for their use in accurate modelling. The results show that these systems can be an auxiliary technique for surveyors and can provide an advantage in some cases.
Article
Full-text available
Intercomparison among six terrestrial laser scanner systems focused on the measurement of small elements (< 0.5 m) is performed. Phase shift (PS) and time of flight (ToF) scanners are considered. Two standard artefacts containing threedimensional printing spheres and steps of variable height are used for the experiment. Results show errors between -4.5 and 3.5 mm in the measurement of distances between step planes. The most stable systems for measuring small elements seem the Leica C10, Faro Photon and Riegl LMS Z390i. The quality of the results is linked to the overall quality of the system rather than the specific technology used for range measurement (PS or ToF) which does not appear to be a determining factor.
Article
Full-text available
The paper presents a synergic and multidisciplinary approach where laser scanner survey, radar interfer-ometric monitoring and finite element (FE) numerical modelling are used for expeditious and no-contact dynamic identification of monumental masonry towers. The methodology is applied to a real case of great historical interest: the "Torre del Mangia" (Mangia's tower) in Siena (Italy). The tower geometry was acquired through Terrestrial Laser Scanning (TLS) techniques. The tower oscillations were detected using an interferometric radar in "Piazza del Campo", the square facing the Mangia's Tower, along three alignments, and movement of the structure at several heights were recorded. A FE model, built on the basis of the geometry acquired through the TLS, was used to interpret and verify the physical meaning of the experimental results. Through the discussion of the case study, the paper shows that the proposed approach can be considered as an effective and expeditious method for assessing the dynamic behavior of monumental buildings (and to plan interventions) on territorial scale.
Article
Full-text available
SUMMARY The terrestrial laser scanning system Trimble GS100 was used in two projects for geometrical building inspection. In this paper, two projects, a water tower and an underground tunnel in Hamburg, are presented wherein geometrical building parameters and discrete points are de- rived from laser scanning data with the goal of inspecting existing buildings relative to con- struction plans. Using data acquired by laser scanning as-built measurements could be com- pared with building plans to determine deviations and possible collisions. The results achieved in these projects demonstrate clearly that terrestrial laser scanning data allows very extensive inspection of buildings due to the high geometrical quality of the point clouds. However, if increased precision (of better than 2mm) is required, the performance potential of the laser scanning system is limited. Since extensive CAD modelling was not necessary for these particular projects very fast results (up to a factor of 1:1 for the ratio of scanning to data processing) have been produced. ZUSAMMENFASSUNG Das terrestrische Laserscanning System Trimble GS100 wurde in zwei Projekten zur Untersuchung von Bauwerken eingesetzt. In diesem Beitrag werden mit dem Wasserturm und dem U-Bahntunnel in Hamburg zwei Projekte vorgestellt, bei denen geometrische Parameter des Gebäudes und diskrete Punkte aus Laserscanningdaten abgeleitet werden, um existierende Gebäude mit Bauplänen zu überprüfen. Anhand der mit dem Laserscanner gewonnenen Daten konnten Bauwerksplanungen mit dem Ist-Bestand hinsichtlich Abweichungen und Kollisionen überprüft werden. Die Ergebnisse zeigen, dass aus Laserscanningdaten abgeleitete Werte sehr umfangreiche Prüfungen zulassen, und dass jedoch bei erhöhten Genauigkeitsanforderungen (von besser als 2 mm) das System an seine Grenzen stößt. Da umfangreiche CAD-Modellierungsarbeiten nicht erforderlich waren, konnten sehr schnell Ergebnisse (bis zu Faktor 1:1 für das Verhältnis Erfassung/Auswertung) erzeugt werden.
Article
The Asinelli and Garisenda towers are the main symbols of the city of Bologna (Italy). These leaning towers, whose heights are about 97 and 48 m respectively, were built during the early 12th century and are two of the few surviving ones from about 100 tall medieval buildings that once characterized the city. Therefore, they are part of the Italian cultural heritage and their safeguard is extremely important. In order to evaluate in detail the deformations of these towers, in particular the deviations from a regular inclination of their walls, the terrestrial laser scanning (TLS) has been used and an efficient direct analysis method has been developed. The towers have been scanned from six viewpoints, providing 19-point clouds with a complete coverage of the visible surfaces with large overlap areas. For each tower, after the registration of the partial point clouds into a common reference frame, an accurate morphological analysis of the acquired surfaces has been carried out. The results show several zones affected by significant deformations and inclination changes. In the case of the Asinelli tower, for which a finite element model is available, the results have also been interpreted on the basis of the static load and normal modes. The correspondence between the measured deformation and the theoretically expected deformation, caused by a seismic sequence, is clear. This fact suggests a high sensibility of the tower to dynamic loads. Although a direct evaluation of the risk cannot be carried out with the obtained results, they lead to the general indication that the structural health of these buildings must be frequently checked and that man-made loads (e.g. vibration due to vehicular traffic) should be avoided or at least reduced.
Article
SUMMARY Cultural heritage recording is a prime application for terrestrial laser scanners due to the high spatial resolution, high accuracy and fast data capture rates offered by this technology. To date, insufficient attention has been given to the many error sources contributing to the uncertainty of scanner datasets. A full error budget is derived for directly georeferenced terrestrial laser scanner networks that considers both relevant error sources fundamental to surveying and those unique to sampled laser scanner systems. In the case of the latter, new probabilistic models are proposed for angular positional uncertainty due to laser beamwidth and target centroid pointing. Analysis of a cultural heritage recording project in Ayutthaya, Thailand, highlights the disparity between 'expected' precision and the more realistic precision indicated by the error budget, to which the laser beamwidth is demonstrated to be a significant contributor.
Article
The romanesque-byzantine style, 1000 year old leaning bell tower of Caorle (Venice Province, Italy) is a unique masonry structure, characterized by single and double lancet windows harmonically distributed on a cylinder-shaped shaft surmounted by a conic cusp. A terrestrial laser scanning (TLS) survey was carried out in 2011 and some analyses were performed on the resulting point cloud to provide the following: bell tower leaning angle, wall inclination/tapering and radius, local deviation from circular shape, and local curvature. Emphasis was placed on the changes of these quantities with elevation. In order to perform these analyses, a MATLAB/Octave toolbox was developed and is available as supplementary material of this paper. In this way, a reliable picture of the current geometry of the bell tower was obtained. In particular, a correlation between leaning angle (average value 1.4° towards East-South-East) and some surface deformations and damage (bulges, brick displacements or also material loss) was found. These results are useful for cultural heritage preservation purposes. © 2012.
Article
The use of Terrestrial Laser Scanning (TLS) data for deformation measurement is gaining increasing interest. This paper is focused on a new procedure for land deformation monitoring based on repeated TLS scans. The kernel of the procedure is the least squares 3D surface matching proposed by Gruen and Akca [Gruen, A., Akca, D., 2005. Least squares 3D surface and curve matching. ISPRS Journal of Photogrammetry and Remote Sensing 59 (3), 151−174]. This paper describes the three main steps of the procedure, namely the acquisition of the TLS data, the global co-registration of the point clouds, and the estimation of the deformation parameters using local surface matchings. The paper briefly outlines the key advantages of the proposed approach, such as the capability to exploit the available high data redundancy using advanced analysis tools, the flexibility of the proposed solution, and the capability of providing fully 3D deformation measurements, including displacement vectors and rotations. Furthermore, it illustrates the performance of the proposed procedure with a validation experiment where a deformation measurement scenario was simulated and TLS and topographic data were acquired. From the analysis of this experiment, interesting features are highlighted: the validation errors below 1 cm in the displacements and below 1 gon in the rotations of small targets measured at a distance of 134 m; the increase by factor two of the errors when the same scene is measured from a distance of 225 m; and the importance of an accurate global co-registration in order to avoid systematic errors in the estimated deformation parameters. It is interesting to note that the above results were achieved under non-optimal conditions, e.g. using non-calibrated data and sub-optimal targets from the matching viewpoint. Besides the simulation experiment, the validation results achieved on landslide test site are briefly discussed.
Article
The automatic co-registration of point clouds, representing 3D surfaces, is a relevant problem in 3D modeling. This multiple registration problem can be defined as a surface matching task. We treat it as least squares matching of overlapping surfaces. The surface may have been digitized/sampled point by point using a laser scanner device, a photogrammetric method or other surface measurement techniques. Our proposed method estimates the transformation parameters of one or more 3D search surfaces with respect to a 3D template surface, using the Generalized Gauss–Markoff model, minimizing the sum of squares of the Euclidean distances between the surfaces. This formulation gives the opportunity of matching arbitrarily oriented 3D surface patches. It fully considers 3D geometry. Besides the mathematical model and execution aspects we address the further extensions of the basic model. We also show how this method can be used for curve matching in 3D space and matching of curves to surfaces. Some practical examples based on the registration of close-range laser scanner and photogrammetric point clouds are presented for the demonstration of the method. This surface matching technique is a generalization of the least squares image matching concept and offers high flexibility for any kind of 3D surface correspondence problem, as well as statistical tools for the analysis of the quality of final matching results.
Geodetic surveys at the temple of Zeus
  • G Georgopoulos
  • E Telioni
Georgopoulos, G. and Telioni, E. 2005. Geodetic surveys at the temple of Zeus, in Nemea, Greece, Technical report (in Greek).
Geometrical building inspection by terrestrial laser scanning Surveyors key role in accelerated development
  • T Kersten
  • H Sternberg
  • C Mechelke
Deformation monitoring and analysis of structures using laser scanners
  • G Roberts
  • L Hirst
Roberts, G. and Hirst, L. 2005. Deformation monitoring and analysis of structures using laser scanners. In: FIG Working Week 2005 and GSDI-8. From Pharaohs to Geoinformatics, Cairo, Egypt, 16-21
Deformation estimation and study of the optical refinements of column K31 of the Temple of Zeus, in Nemea, using terrestrial laser scanner
  • A Tsontzou
Tsontzou, A. 2014. Deformation estimation and study of the optical refinements of column K31 of the Temple of Zeus, in Nemea, using terrestrial laser scanner., Diploma thesis (in Greek). School of Rural & Surveying Engineering, N.T.U. Athens, 180 p.
Measurements of K31 refinements for restoration purposes
  • K Zambas
Zambas, K. 2000. Measurements of K31 refinements for restoration purposes, Technical report (in Greek).
Geometric modeling of a large dam by terrestrial laser scanning
  • M Alba
  • A Guissani
  • F Roncoroni
  • M Scaioni
  • P Valgoi
Alba, M., Guissani, A., Roncoroni, F., Scaioni, M. and Valgoi, P. 2006. Geometric modeling of a large dam by terrestrial laser scanning. In: XXIII FIG Congress, Shaping the change, Munich, Germany, October 8-13.
Terrestrial laser scanning for preserving cultural heritage: analysis of geometric anomalies for ancient structures
  • C Castagnietti
  • E Bertacchini
  • A Capra
  • M Dubini
Castagnietti, C., Bertacchini, E., Capra, A. and Dubini, M. 2012. Terrestrial laser scanning for preserving cultural heritage: analysis of geometric anomalies for ancient structures. In: FIG Working Week 2012. Knowing to manage the territory, protect the environment, evaluate the cultural heritage, Rome, Italy, 6-10 May.
The refinements of the Parthenon columns
  • K Zambas
Zambas, K. 1998. The refinements of the Parthenon columns. Ph D. Thesis (in Greek). N.T.U. Athens, 254 p.