Sensors

Research

Jump to: Other

44 pages, 18175 KiB

Open AccessArticle

Introduction of Deep Learning in Thermographic Monitoring of Cultural Heritage and Improvement by Automatic Thermogram Pre-Processing Algorithms

by Iván Garrido, Jorge Erazo-Aux, Susana Lagüela, Stefano Sfarra, Clemente Ibarra-Castanedo, Elena Pivarčiová, Gianfranco Gargiulo, Xavier Maldague and Pedro Arias

Sensors 2021, 21(3), 750; https://doi.org/10.3390/s21030750 - 22 Jan 2021

Cited by 24 | Viewed by 4048

Abstract

The monitoring of heritage objects is necessary due to their continuous deterioration over time. Therefore, the joint use of the most up-to-date inspection techniques with the most innovative data processing algorithms plays an important role to apply the required prevention and conservation tasks [...] Read more.

The monitoring of heritage objects is necessary due to their continuous deterioration over time. Therefore, the joint use of the most up-to-date inspection techniques with the most innovative data processing algorithms plays an important role to apply the required prevention and conservation tasks in each case study. InfraRed Thermography (IRT) is one of the most used Non-Destructive Testing (NDT) techniques in the cultural heritage field due to its advantages in the analysis of delicate objects (i.e., undisturbed, non-contact and fast inspection of large surfaces) and its continuous evolution in both the acquisition and the processing of the data acquired. Despite the good qualitative and quantitative results obtained so far, the lack of automation in the IRT data interpretation predominates, with few automatic analyses that are limited to specific conditions and the technology of the thermographic camera. Deep Learning (DL) is a data processor with a versatile solution for highly automated analysis. Then, this paper introduces the latest state-of-the-art DL model for instance segmentation, Mask Region-Convolution Neural Network (Mask R-CNN), for the automatic detection and segmentation of the position and area of different surface and subsurface defects, respectively, in two different artistic objects belonging to the same family: Marquetry. For that, active IRT experiments are applied to each marquetry. The thermal image sequences acquired are used as input dataset in the Mask R-CNN learning process. Previously, two automatic thermal image pre-processing algorithms based on thermal fundamentals are applied to the acquired data in order to improve the contrast between defective and sound areas. Good detection and segmentation results are obtained regarding state-of-the-art IRT data processing algorithms, which experience difficulty in identifying the deepest defects in the tests. In addition, the performance of the Mask R-CNN is improved by the prior application of the proposed pre-processing algorithms. Full article

(This article belongs to the Special Issue Sensors for Cultural Heritage Monitoring)

► Show Figures

Figure 1

16 pages, 5655 KiB

Open AccessArticle

Design and Validation of a Scalable, Reconfigurable and Low-Cost Structural Health Monitoring System

by Juan J. Villacorta, Lara del-Val, Roberto D. Martínez, José-Antonio Balmori, Álvaro Magdaleno, Gamaliel López, Alberto Izquierdo, Antolín Lorenzana and Luis-Alfonso Basterra

Sensors 2021, 21(2), 648; https://doi.org/10.3390/s21020648 - 19 Jan 2021

Cited by 16 | Viewed by 3920

Abstract

This paper presents the design, development and testing of a low-cost Structural Health Monitoring (SHM) system based on MEMS (Micro Electro-Mechanical Systems) triaxial accelerometers. A new control system composed by a myRIO platform, managed by specific LabVIEW software, has been developed. The LabVIEW [...] Read more.

This paper presents the design, development and testing of a low-cost Structural Health Monitoring (SHM) system based on MEMS (Micro Electro-Mechanical Systems) triaxial accelerometers. A new control system composed by a myRIO platform, managed by specific LabVIEW software, has been developed. The LabVIEW software also computes the frequency response functions for the subsequent modal analysis. The proposed SHM system was validated by comparing the data measured by this set-up with a conventional SHM system based on piezoelectric accelerometers. After carrying out some validation tests, a high correlation can be appreciated in the behavior of both systems, being possible to conclude that the proposed system is sufficiently accurate and sensitive for operative purposes, apart from being significantly more affordable than the traditional one. Full article

(This article belongs to the Special Issue Sensors for Cultural Heritage Monitoring)

► Show Figures

Figure 1

28 pages, 6965 KiB

Open AccessArticle

A Methodology for Discriminant Time Series Analysis Applied to Microclimate Monitoring of Fresco Paintings

by Sandra Ramírez, Manuel Zarzo, Angel Perles and Fernando-Juan García-Diego

Sensors 2021, 21(2), 436; https://doi.org/10.3390/s21020436 - 09 Jan 2021

Cited by 10 | Viewed by 2746

Abstract

The famous Renaissance frescoes in Valencia’s Cathedral (Spain) have been kept under confined temperature and relative humidity (RH) conditions for about 300 years, until the removal of the baroque vault covering them in 2006. In the interest of longer-term preservation and in order [...] Read more.

The famous Renaissance frescoes in Valencia’s Cathedral (Spain) have been kept under confined temperature and relative humidity (RH) conditions for about 300 years, until the removal of the baroque vault covering them in 2006. In the interest of longer-term preservation and in order to maintain these frescoes in good condition, a unique monitoring system was implemented to record both air temperature and RH. Sensors were installed at different points at the vault of the apse during the restoration process. The present study proposes a statistical methodology for analyzing a subset of RH data recorded by the sensors in 2008 and 2010. This methodology is based on fitting different functions and models to the time series, in order to classify the different sensors.The methodology proposed, computes classification variables and applies a discriminant technique to them. The classification variables correspond to estimates of model parameters of and features such as mean and maximum, among others. These features are computed using values of functions such as spectral density, sample autocorrelation (sample ACF), sample partial autocorrelation (sample PACF), and moving range (MR). The classification variables computed were structured as a matrix. Next, sparse partial least squares discriminant analysis (sPLS-DA) was applied in order to discriminate sensors according to their position in the vault. It was found that the classification of sensors derived from Seasonal ARIMA-TGARCH showed the best performance (i.e., lowest classification error rate). Based on these results, the methodology applied here could be useful for characterizing the differences in RH, measured at different positions in a historical building. Full article

(This article belongs to the Special Issue Sensors for Cultural Heritage Monitoring)

► Show Figures

Figure 1

24 pages, 41317 KiB

Open AccessArticle

Optimal Lateral Displacement in Automatic Close-Range Photogrammetry

by Gabriele Guidi, Umair Shafqat Malik and Laura Loredana Micoli

Sensors 2020, 20(21), 6280; https://doi.org/10.3390/s20216280 - 04 Nov 2020

Cited by 9 | Viewed by 3086

Abstract

Based on the use of automatic photogrammetry, different researchers made evident that the level of overlap between adjacent photographs directly affects the uncertainty of the 3D dense cloud originated by the Structure from Motion/Image Matching (SfM/IM) process. The purpose of this study was [...] Read more.

Based on the use of automatic photogrammetry, different researchers made evident that the level of overlap between adjacent photographs directly affects the uncertainty of the 3D dense cloud originated by the Structure from Motion/Image Matching (SfM/IM) process. The purpose of this study was to investigate if, in the case of a convergent shooting typical of close-range photogrammetry, an optimal lateral displacement of the camera for minimizing the 3D data uncertainty could be identified. We examined five different test objects made of rock, differing in terms of stone type and visual appearance. First, an accurate reference data set was generated by acquiring each object with an active range device, based on pattern projection (σ_z = 18 µm). Then, each object was 3D-captured with photogrammetry, using a set of images taken radially, with the camera pointing to the center of the specimen. The camera–object minimum distance was kept at 200 mm during the shooting, and the angular displacement was as small as π/60. We generated several dense clouds by sampling the original redundant sequence at angular displacements (nπ/60, n = 1, 2, … 8). Each 3D cloud was then compared with the reference, implementing an accurate scaling protocol to minimize systematic errors. The residual standard deviation of error made consistently evident a range of angular displacements among images that appear to be optimal for reducing the measurement uncertainty, independent of each specimen shape, material, and texture. Such a result provides guidance about how best to arrange the cameras’ geometry for 3D digitization of a stone cultural heritage artifact with several convergent shots. The photogrammetric tool used in the experiments was Agisoft Metashape. Full article

(This article belongs to the Special Issue Sensors for Cultural Heritage Monitoring)

► Show Figures

Figure 1

26 pages, 15659 KiB

Open AccessArticle

LiDAR- and AR-Based Monitoring of Evolved Building Façades upon Zoning Conflicts

by Naai-Jung Shih and Yi Chen

Sensors 2020, 20(19), 5628; https://doi.org/10.3390/s20195628 - 01 Oct 2020

Cited by 4 | Viewed by 2647

Abstract

Zoning conflicts have transformed Old Street fabrics in terms of architectural style and construction material in Lukang, Taiwan. This transformation should be assessed as a contribution to digital cultural sustainability. The objective of this study was to compare the evolved façades resultant from [...] Read more.

Zoning conflicts have transformed Old Street fabrics in terms of architectural style and construction material in Lukang, Taiwan. This transformation should be assessed as a contribution to digital cultural sustainability. The objective of this study was to compare the evolved façades resultant from the changes made by the development of architectural history and urban planning. A combination of 3D scan technology and a smartphone augmented reality (AR) app, Augment^®, was applied to the situated comparison with direct interaction on-site. The AR application compared 20 façades in the laboratory and 18 façades in four different sites using a flexible interface. The comparisons identified the correlation of evolved façades in real sites in terms of building volumes and components, pedestrian arcades on store fronts, and previous installations. The situated comparisons were facilitated in a field study with real-time adjustments to 3D models and analyses of correlations across details and components. The application of AR was demonstrated to be effective in reinstalling scenes and differentiating diversified compositions of vocabulary in a remote site. Full article

(This article belongs to the Special Issue Sensors for Cultural Heritage Monitoring)

► Show Figures

Figure 1

19 pages, 8727 KiB

Open AccessArticle

Integrated Use of Measurements for the Structural Diagnosis in Historical Vaulted Buildings

by Giuliana Cardani and Grigor Angjeliu

Sensors 2020, 20(15), 4290; https://doi.org/10.3390/s20154290 - 31 Jul 2020

Cited by 12 | Viewed by 2659

Abstract

The process of the structural diagnosis of historical buildings is analyzed. The correlation of different data is a fundamental issue, related to the multidisciplinary nature of the study of built heritage. Quantitative data are collected by sensors, these being environmental data (temperature and [...] Read more.

The process of the structural diagnosis of historical buildings is analyzed. The correlation of different data is a fundamental issue, related to the multidisciplinary nature of the study of built heritage. Quantitative data are collected by sensors, these being environmental data (temperature and humidity) or cracks (displacements). Another important source being qualitative data, derived from historic investigation, diagnostic investigations, etc. However sometimes the results may be difficult to correlate due to the different nature of the data, being quantitative and qualitative, as well as spread over the long life of the construction. In particular, the here proposed methodology suggests the use of light detection and ranging (LiDAR) scanning for the geometric and structural deformation survey, damage survey, historic evolution, monitoring of the crack pattern and environmental data. The integrated use of the collected data with digital and finite element models is investigated in two case studies. The combined use of the set of collected data is shown to be fundamental to the interpretation of the active damage mechanisms in the system, and for making appropriate decisions related to their safety. Finally, a guideline is proposed to allow for a more general use of the herein proposed structural diagnosis procedure. Full article

(This article belongs to the Special Issue Sensors for Cultural Heritage Monitoring)

► Show Figures

Figure 1

17 pages, 6379 KiB

Open AccessArticle

A Genetic Algorithm Procedure for the Automatic Updating of FEM Based on Ambient Vibration Tests

by Francesca Bianconi, Georgios Panagiotis Salachoris, Francesco Clementi and Stefano Lenci

Sensors 2020, 20(11), 3315; https://doi.org/10.3390/s20113315 - 10 Jun 2020

Cited by 47 | Viewed by 3471

Abstract

The dynamic identification of the modal parameters of a structure, in order to gain control of its functionality under operating conditions, is currently under discussion from a scientific and technical point of views. The experimental observations obtained through structural health monitoring (SHM) are [...] Read more.

The dynamic identification of the modal parameters of a structure, in order to gain control of its functionality under operating conditions, is currently under discussion from a scientific and technical point of views. The experimental observations obtained through structural health monitoring (SHM) are a useful calibration reference of numerical models (NMs). In this paper, the procedures for the identification of modal parameters in historical bell towers using a stochastic subspace identification (SSI) algorithm are presented. Then, NMs are manually calibrated on the identification’s results. Finally, the applicability of a genetic algorithm for the automatic calibration of the elastic parameters is considered with the aim of searching for the properties of the autochthonous material, in order to reduce modelling error following the model assurance criterion (MAC). In this regard, several material values on the same model are examined to see how to approach the evolution and the distribution of these features, comparing the characterization proposed by the genetic algorithm with the results considered by the manual iterative procedure. Full article

(This article belongs to the Special Issue Sensors for Cultural Heritage Monitoring)

► Show Figures

Figure 1

18 pages, 1564 KiB

Open AccessArticle

A Comprehensive Study of the Microclimate-Induced Conservation Risks in Hypogeal Sites: The Mithraeum of the Baths of Caracalla (Rome)

by Francesca Frasca, Elena Verticchio, Alessia Caratelli, Chiara Bertolin, Dario Camuffo and Anna Maria Siani

Sensors 2020, 20(11), 3310; https://doi.org/10.3390/s20113310 - 10 Jun 2020

Cited by 15 | Viewed by 3358

Abstract

The peculiar microclimate inside cultural hypogeal sites needs to be carefully investigated. This study presents a methodology that aimed at providing a user-friendly assessment of the frequently occurring hazards in such sites. A Risk Index was specifically defined as the percentage of time [...] Read more.

The peculiar microclimate inside cultural hypogeal sites needs to be carefully investigated. This study presents a methodology that aimed at providing a user-friendly assessment of the frequently occurring hazards in such sites. A Risk Index was specifically defined as the percentage of time for which the hygrothermal values lie in ranges that are considered to be hazardous for conservation. An environmental monitoring campaign that was conducted over the past ten years inside the Mithraeum of the Baths of Caracalla (Rome) allowed for us to study the deterioration before and after a maintenance intervention. The general microclimate assessment and the specific conservation risk assessment were both carried out. The former made it possible to investigate the influence of the outdoor weather conditions on the indoor climate and estimate condensation and evaporation responsible for salts crystallisation/dissolution and bio-colonisation. The latter took hygrothermal conditions that were close to wall surfaces to analyse the data distribution on diagrams with critical curves of deliquescence salts, mould germination, and growth. The intervention mitigated the risk of efflorescence thanks to reduced evaporation, while promoting the risk of bioproliferation due to increased condensation. The Risk Index provided a quantitative measure of the individual risks and their synergism towards a more comprehensive understanding of the microclimate-induced risks. Full article

(This article belongs to the Special Issue Sensors for Cultural Heritage Monitoring)

► Show Figures

Graphical abstract

33 pages, 10014 KiB

Open AccessArticle

Analysis of the Selection Impact of 2D Detectors on the Accuracy of Image-Based TLS Data Registration of Objects of Cultural Heritage and Interiors of Public Utilities

by Jakub Markiewicz and Dorota Zawieska

Sensors 2020, 20(11), 3277; https://doi.org/10.3390/s20113277 - 09 Jun 2020

Cited by 6 | Viewed by 2350

Abstract

The aim of this article is to present the influence of detector selection for the image-based Terrestrial Laser Scanning (TLS) registration method. The presented results are the extended continuation of investigations presented in the article, ‘The Influence of the Cartographic Transformation of TLS [...] Read more.

The aim of this article is to present the influence of detector selection for the image-based Terrestrial Laser Scanning (TLS) registration method. The presented results are the extended continuation of investigations presented in the article, ‘The Influence of the Cartographic Transformation of TLS Data on the Quality of the Automatic Registration’. In order to obtain the correct results of the TLS registration process, it is necessary to detect and match the correct tie points, which are evenly distributed across the entire area. Commonly, for TLS data registration manually or semi-manually corresponding points are detected. However, when large, complicated cultural heritage objects are investigated, it is sometimes impossible to place marked control points. The only possibility of resolving this problem is the use of image-based TLS data registration. One of the most important factors that influences the quality and ability to use it correctly, is accurate selection. For this purpose, the authors decided to test three blob detectors ASIFT, SURF, CenSurE, and two point detectors FAST and BRISK. The results indicated that selection depends on two factors: if the time required for data processing is not important, the ASIFT algorithm should be used, which allows for full registration, but if not, a combination of other algorithms with results supervision should be considered. Full article

(This article belongs to the Special Issue Sensors for Cultural Heritage Monitoring)

► Show Figures

Figure 1

19 pages, 4887 KiB

Open AccessArticle

Suitability of Automatic Photogrammetric Reconstruction Configurations for Small Archaeological Remains

by Manuel Rodríguez-Martín and Pablo Rodríguez-Gonzálvez

Sensors 2020, 20(10), 2936; https://doi.org/10.3390/s20102936 - 22 May 2020

Cited by 15 | Viewed by 3147

Abstract

Three-dimensional (3D) reconstruction is a useful technique for the documentation, characterization, and evaluation of small archeological objects. In this research, a comparison among different photogrammetric setups that use different lenses (macro and standard zoom) and dense point cloud generation calibration processes for real [...] Read more.

Three-dimensional (3D) reconstruction is a useful technique for the documentation, characterization, and evaluation of small archeological objects. In this research, a comparison among different photogrammetric setups that use different lenses (macro and standard zoom) and dense point cloud generation calibration processes for real specific objects of archaeological interest with different textures, geometries, and materials is raised using an automated data collection. The data acquisition protocol is carried out from a platform with control points referenced with a metrology absolute arm to accurately define a common spatial reference system. The photogrammetric reconstruction is performed considering a camera pre-calibration as well as a self-calibration. The latter is common for most data acquisition situations in archaeology. The results for the different lenses and calibration processes are compared based on a robust statistical analysis, which entails the estimation of both standard Gaussian and non-parametric estimators, to assess the accuracy potential of different configurations. As a result, 95% of the reconstructed points show geometric discrepancies lower than 0.85 mm for the most unfavorable case and less than 0.35 mm for the other cases. Full article

(This article belongs to the Special Issue Sensors for Cultural Heritage Monitoring)

► Show Figures

Figure 1

39 pages, 10598 KiB

Open AccessArticle

The Quality Assessment of Different Geolocalisation Methods for a Sensor System to Monitor Structural Health of Monumental Objects

by Jakub Markiewicz, Sławomir Łapiński, Patryk Kot, Aleksandra Tobiasz, Magomed Muradov, Joanna Nikel, Andy Shaw and Ahmed Al-Shamma’a

Sensors 2020, 20(10), 2915; https://doi.org/10.3390/s20102915 - 21 May 2020

Cited by 17 | Viewed by 3315

Abstract

Cultural heritage objects are affected by a wide range of factors causing their deterioration and decay over time such as ground deformations, changes in hydrographic conditions, vibrations or excess of moisture, which can cause scratches and cracks formation in the case of historic [...] Read more.

Cultural heritage objects are affected by a wide range of factors causing their deterioration and decay over time such as ground deformations, changes in hydrographic conditions, vibrations or excess of moisture, which can cause scratches and cracks formation in the case of historic buildings. The electromagnetic spectroscopy has been widely used for non-destructive structural health monitoring of concrete structures. However, the limitation of this technology is a lack of geolocalisation in the space for multispectral architectural documentation. The aim of this study is to examine different geolocalisation methods in order to determine the position of the sensor system, which will then allow to georeference the results of measurements performed by this device and apply corrections to the sensor response, which is a crucial element required for further data processing related to the object structure and its features. The classical surveying, terrestrial laser scanning (TLS), and Structure-from-Motion (SfM) photogrammetry methods were used in this investigation at three test sites. The methods were reviewed and investigated. The results indicated that TLS technique should be applied for simple structures and plain textures, while the SfM technique should be used for marble-based and other translucent or semi-translucent structures in order to achieve the highest accuracy for geolocalisation of the proposed sensor system. Full article

(This article belongs to the Special Issue Sensors for Cultural Heritage Monitoring)

► Show Figures

Figure 1

13 pages, 2852 KiB

Open AccessArticle

Hyper-Spectral Imaging Technique in the Cultural Heritage Field: New Possible Scenarios

by Marcello Picollo, Costanza Cucci, Andrea Casini and Lorenzo Stefani

Sensors 2020, 20(10), 2843; https://doi.org/10.3390/s20102843 - 16 May 2020

Cited by 83 | Viewed by 5987

Abstract

Imaging spectroscopy technique was introduced in the cultural heritage field in the 1990s, when a multi-spectral imaging system based on a Vidicon camera was used to identify and map pigments in paintings. Since then, with continuous improvements in imaging technology, the quality of [...] Read more.

Imaging spectroscopy technique was introduced in the cultural heritage field in the 1990s, when a multi-spectral imaging system based on a Vidicon camera was used to identify and map pigments in paintings. Since then, with continuous improvements in imaging technology, the quality of spectroscopic information in the acquired imaging data has greatly increased. Moreover, with the progressive transition from multispectral to hyperspectral imaging techniques, numerous new applicative perspectives have become possible, ranging from non-invasive monitoring to high-quality documentation, such as mapping and characterization of polychrome and multi-material surfaces of cultural properties. This article provides a brief overview of recent developments in the rapidly evolving applications of hyperspectral imaging in this field. The fundamentals of the various strategies, that have been developed for applying this technique to different types of artworks are discussed, together with some examples of recent applications. Full article

(This article belongs to the Special Issue Sensors for Cultural Heritage Monitoring)

► Show Figures

Figure 1

35 pages, 11047 KiB

Open AccessArticle

Tower of Belém (Lisbon)–Status Quo 3D Documentation and Material Origin Determination

by Paula Redweik, José Juan de Sanjosé Blasco, Manuel Sánchez-Fernández, Alan D. Atkinson and Luís Francisco Martínez Corrales

Sensors 2020, 20(8), 2355; https://doi.org/10.3390/s20082355 - 21 Apr 2020

Cited by 2 | Viewed by 4131

Abstract

The Tower of Belém, an early 16th century defense tower located at the mouth of the Tagus river, is the iconic symbol of Lisbon. It belongs to the Belém complex, classified since 1983 as a World Heritage Site by the UNESCO, and it [...] Read more.

The Tower of Belém, an early 16th century defense tower located at the mouth of the Tagus river, is the iconic symbol of Lisbon. It belongs to the Belém complex, classified since 1983 as a World Heritage Site by the UNESCO, and it is the second most visited monument in Portugal. On November 1st, 1755, there was a heavy earthquake in Lisbon followed by a tsunami, causing between 60,000 and 100,000 deaths. There is a possibility of a repetition of such a catastrophe, which could bring about the collapse of the structure. This was the reasoning behind the decision to evaluate the Tower of Belém by means of surveys using Terrestrial Laser Scanning and photogrammetry. Until now, there was no high-resolution 3D model of the interior and exterior of the tower. A complete 3D documentation of the state of the Tower was achieved with a cloud of more than 6,200 million 3D points in the ETRS89 PT-TM06 coordinate system. Additionally, measurements were made using a hyperspectral camera and a spectroradiometer to characterize the stone material used in the Tower. The result is a digital 3D representation of the Tower of Belém, and the identification of the quarries that may have been used to extract its stone. The work carried out combines geometrical and material analysis. The methods used may constitute a guide when documenting and intervening in similar heritage elements. Finally, the information contained therein will allow an eventual reconstruction of the Tower in the case of another catastrophe. Full article

(This article belongs to the Special Issue Sensors for Cultural Heritage Monitoring)

► Show Figures

Figure 1

28 pages, 6764 KiB

Open AccessArticle

Virtual Disassembling of Historical Edifices: Experiments and Assessments of an Automatic Approach for Classifying Multi-Scalar Point Clouds into Architectural Elements

by Arnadi Murtiyoso and Pierre Grussenmeyer

Sensors 2020, 20(8), 2161; https://doi.org/10.3390/s20082161 - 11 Apr 2020

Cited by 24 | Viewed by 4083

Abstract

3D heritage documentation has seen a surge in the past decade due to developments in reality-based 3D recording techniques. Several methods such as photogrammetry and laser scanning are becoming ubiquitous amongst architects, archaeologists, surveyors, and conservators. The main result of these methods is [...] Read more.

3D heritage documentation has seen a surge in the past decade due to developments in reality-based 3D recording techniques. Several methods such as photogrammetry and laser scanning are becoming ubiquitous amongst architects, archaeologists, surveyors, and conservators. The main result of these methods is a 3D representation of the object in the form of point clouds. However, a solely geometric point cloud is often insufficient for further analysis, monitoring, and model predicting of the heritage object. The semantic annotation of point clouds remains an interesting research topic since traditionally it requires manual labeling and therefore a lot of time and resources. This paper proposes an automated pipeline to segment and classify multi-scalar point clouds in the case of heritage object. This is done in order to perform multi-level segmentation from the scale of a historical neighborhood up until that of architectural elements, specifically pillars and beams. The proposed workflow involves an algorithmic approach in the form of a toolbox which includes various functions covering the semantic segmentation of large point clouds into smaller, more manageable and semantically labeled clusters. The first part of the workflow will explain the segmentation and semantic labeling of heritage complexes into individual buildings, while a second part will discuss the use of the same toolbox to segment the resulting buildings further into architectural elements. The toolbox was tested on several historical buildings and showed promising results. The ultimate intention of the project is to help the manual point cloud labeling, especially when confronted with the large training data requirements of machine learning-based algorithms. Full article

(This article belongs to the Special Issue Sensors for Cultural Heritage Monitoring)

► Show Figures

Figure 1

14 pages, 2664 KiB

Open AccessArticle

Real-Time Wood Behaviour: The Use of Strain Gauges for Preventive Conservation Applications

by Willemien Anaf, Ana Cabal, Mie Robbe and Olivier Schalm

Sensors 2020, 20(1), 305; https://doi.org/10.3390/s20010305 - 06 Jan 2020

Cited by 9 | Viewed by 4045

Abstract

Within the heritage field, the application of strain gauges on wood surfaces is a little-explored but inexpensive and effective method to analyse the environmental appropriateness of rooms for the wooden heritage collections they contain. This contribution proposes a wood sensor connected to a [...] Read more.

Within the heritage field, the application of strain gauges on wood surfaces is a little-explored but inexpensive and effective method to analyse the environmental appropriateness of rooms for the wooden heritage collections they contain. This contribution proposes a wood sensor connected to a data logger to identify short moments with an elevated risk of harm. Two experiments were performed to obtain insights pertaining to the applicability of wood sensors to evaluate preservation conditions. (1) The representativeness of strain gauges on dummies was tested for their use in evaluating the preservation conditions of a range of wooden objects exposed to the same environment. For this, three situations were mimicked: a bare wood surface, a wood surface covered with a preparation layer, and a wood surface covered with a preparation and varnish layer. (2) The usability of strain gauges to monitor the wood behaviour in real-time measurements was tested with a monitoring campaign of almost two years in a church where a new heating system was installed. The results of both experiments are promising, and the authors encourage a broader application of strain gauges in the heritage field. Full article

(This article belongs to the Special Issue Sensors for Cultural Heritage Monitoring)

► Show Figures

Figure 1

22 pages, 20102 KiB

Open AccessArticle

A Gaussian Process Model for Color Camera Characterization: Assessment in Outdoor Levantine Rock Art Scenes

by Adolfo Molada-Tebar, Gabriel Riutort-Mayol, Ángel Marqués-Mateu and José Luis Lerma

Sensors 2019, 19(21), 4610; https://doi.org/10.3390/s19214610 - 23 Oct 2019

Cited by 6 | Viewed by 2836

Abstract

In this paper, we propose a novel approach to undertake the colorimetric camera characterization procedure based on a Gaussian process (GP). GPs are powerful and flexible nonparametric models for multivariate nonlinear functions. To validate the GP model, we compare the results achieved with [...] Read more.

In this paper, we propose a novel approach to undertake the colorimetric camera characterization procedure based on a Gaussian process (GP). GPs are powerful and flexible nonparametric models for multivariate nonlinear functions. To validate the GP model, we compare the results achieved with a second-order polynomial model, which is the most widely used regression model for characterization purposes. We applied the methodology on a set of raw images of rock art scenes collected with two different Single Lens Reflex (SLR) cameras. A leave-one-out cross-validation (LOOCV) procedure was used to assess the predictive performance of the models in terms of CIE XYZ residuals and

Δ E_{a b}^{*}

color differences. Values of less than 3 CIELAB units were achieved for

Δ E_{a b}^{*}

. The output sRGB characterized images show that both regression models are suitable for practical applications in cultural heritage documentation. However, the results show that colorimetric characterization based on the Gaussian process provides significantly better results, with lower values for residuals and

Δ E_{a b}^{*}

. We also analyzed the induced noise into the output image after applying the camera characterization. As the noise depends on the specific camera, proper camera selection is essential for the photogrammetric work. Full article

(This article belongs to the Special Issue Sensors for Cultural Heritage Monitoring)

► Show Figures

Figure 1

11 pages, 2490 KiB

Open AccessArticle

High Energy Double Peak Pulse Laser Induced Plasma Spectroscopy for Metal Characterization Using a Passively Q-Switched Laser Source and CCD Detector

by Juri Agresti, Andrea Azelio Mencaglia and Salvatore Siano

Sensors 2019, 19(17), 3634; https://doi.org/10.3390/s19173634 - 21 Aug 2019

Cited by 1 | Viewed by 3125

Abstract

Here, the development and testing of a portable double peak pulse laser induced plasma spectroscopy (DPP-LIPS) based on passively Q-switched Nd:YAG (Neodymium-doped Yttrium Aluminum Garnet) laser excitation is reported. The latter delivered structured laser pulses at a repetition rate of up to 20 [...] Read more.

Here, the development and testing of a portable double peak pulse laser induced plasma spectroscopy (DPP-LIPS) based on passively Q-switched Nd:YAG (Neodymium-doped Yttrium Aluminum Garnet) laser excitation is reported. The latter delivered structured laser pulses at a repetition rate of up to 20 Hz, including two energy peaks of about 100 mJ each with a relative temporal spacing of about 80 µs. Plasma spectra were collected using a low-cost Czerny–Turner spectrometer equipped with a non-intensified CCD (Charge-Coupled Device) array. Such a DPP-LIPS setup is technologically simpler and cheaper than the usual ones. Despite the relatively large temporal separation between the mentioned laser peaks, significant spectral intensity enhancements with respect to the usual single peak pulse configuration were observed. The amplification factor measured ranged between 2 and 10, depending on the specific emission peaks and the Q-switched configuration, and a consequent significant improvement of the detection limit of trace elements was observed. The instrument was calibrated for the quantitative analysis of copper alloy through systematic measurements carried out on reference samples and was then tested in an example archaeometric characterization of a statuette from the Egyptian Museum of Florence. Full article

(This article belongs to the Special Issue Sensors for Cultural Heritage Monitoring)

► Show Figures

Figure 1

25 pages, 6094 KiB

Open AccessArticle

Acoustic Sensor Data Flow for Cultural Heritage Monitoring and Safeguarding

by Panagiotis Kasnesis, Nicolaos-Alexandros Tatlas, Stelios A. Mitilineos, Charalampos Z. Patrikakis and Stelios M. Potirakis

Sensors 2019, 19(7), 1629; https://doi.org/10.3390/s19071629 - 05 Apr 2019

Cited by 10 | Viewed by 4058

Abstract

Cultural heritage sites, apart from being the tangible link to a country’s history and culture, actively contribute to the national economy, offering a foundation upon which cultural tourism can develop. This importance at the cultural and economic level, advocates for the need for [...] Read more.

Cultural heritage sites, apart from being the tangible link to a country’s history and culture, actively contribute to the national economy, offering a foundation upon which cultural tourism can develop. This importance at the cultural and economic level, advocates for the need for preservation of cultural heritage sites for the future generations. To this end, advanced monitoring systems harnessing the power of sensors are deployed near the sites to collect data which can fuel systems and processes aimed at protection and preservation. In this paper we present the use of acoustic sensors for safeguarding cultural sites located in rural or urban areas, based on a novel data flow framework. We developed and deployed Wireless Acoustic Sensors Networks that record audio signals, which are transferred to a modular cloud platform to be processed using an efficient deep learning algorithm (f1-score: 0.838) to identify audio sources of interest for each site, taking into account the materials the assets are made of. The extracted information is presented exploiting the designed STORM Audio Signal ontology and then fused with spatiotemporal information using semantic rules. The results of this work give valuable insight to the cultural experts and are publicly available using the Linked Open Data format. Full article

(This article belongs to the Special Issue Sensors for Cultural Heritage Monitoring)

► Show Figures

Figure 1

Other

Jump to: Research

13 pages, 3692 KiB

Open AccessLetter

Development of an IoT Structural Monitoring System Applied to a Hypogeal Site

by Alessio De Angelis, Francesco Santoni, Paolo Carbone, Manuela Cecconi, Alessia Vecchietti and Francesco Di Lorenzo

Sensors 2020, 20(23), 6769; https://doi.org/10.3390/s20236769 - 26 Nov 2020

Cited by 8 | Viewed by 2170

Abstract

This paper describes the development of a distributed sensing system that can be disseminated in an environment of interest to monitor the vibration of a structure. This low-cost system consists of several sensor nodes and a central receiving node. All nodes are built [...] Read more.

This paper describes the development of a distributed sensing system that can be disseminated in an environment of interest to monitor the vibration of a structure. This low-cost system consists of several sensor nodes and a central receiving node. All nodes are built using off-the-shelf electronic components. Each of the sensor nodes is battery-powered and equipped with a triaxial MEMS accelerometer, a wireless Long Range (LoRa) transceiver module for data transmission, a GPS module used for synchronization, and a microcontroller. The operation of the sensor node is validated by controlled laboratory tests where it is compared to a commercial reference accelerometer. Furthermore, the feasibility and potential benefits of the application of the proposed system to a structure in an archaeological site is investigated. Results show that the proposed sensor node could successfully monitor the vibration at several locations within the site. Therefore, it may be employed to detect the most relevant stresses to the structure, allowing for the identification of risks. Full article

(This article belongs to the Special Issue Sensors for Cultural Heritage Monitoring)

► Show Figures

Figure 1

28 pages, 20225 KiB

Open AccessLetter

Digital Cultural Heritage Preservation in Art Painting: A Surface Roughness Approach to the Brush Strokes

by Anna Mironova, Frederic Robache, Raphael Deltombe, Robin Guibert, Ludovic Nys and Maxence Bigerelle

Sensors 2020, 20(21), 6269; https://doi.org/10.3390/s20216269 - 03 Nov 2020

Cited by 13 | Viewed by 4423

Abstract

There is a growing interest in cultural heritage preservation. The notion of HyperHeritage highlights the creation of new means of communication for the perception and data processing in cultural heritage. This article presents the Digital Surface HyperHeritage approach, an academic project to identify [...] Read more.

There is a growing interest in cultural heritage preservation. The notion of HyperHeritage highlights the creation of new means of communication for the perception and data processing in cultural heritage. This article presents the Digital Surface HyperHeritage approach, an academic project to identify the topography of art painting surfaces at the scale at which the elementary information of sensorial rendering is contained. High-resolution roughness and imaging measurement tools are then required. The high-resolution digital model of painted surfaces provides a solid foundation for artwork-related information and is a source of many potential opportunities in the fields of identification, conservation, and restoration. It can facilitate the determination of the operations used by the artist in the creative process and allow art historians to define, for instance, the meaning, provenance, or authorship of a masterpiece. The Digital Surface HyperHeritage approach also includes the development of a database for archiving and sharing the topographic signature of a painting. Full article

(This article belongs to the Special Issue Sensors for Cultural Heritage Monitoring)

► Show Figures

Graphical abstract

Journal Menu

Journal Browser

Sensors for Cultural Heritage Monitoring

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Related Special Issue

Published Papers (20 papers)

Research

Other

Further Information

Guidelines

MDPI Initiatives

Follow MDPI