Understanding Uncertainties in Thermographic Imaging

7 p.The present article proposes a workflow based on free/open-source software solutions for the acquisition of competences in engineering courses related to the use of thermographic images. The approach is aimed to three-dimensional visualization techniques over thermographic images to improve the comprehension and interpretation of the different error sources that affects the measurements, and therefore the conclusions and analysis derived from them. The present work is framed inside the virtual laboratories discipline, as the new learning material can be employed for the acquisition of competences and skills. Additionally, it can be used for the evaluation of competences in asynchronous and e-learning programs. The learning materials could be easily deployed in a learning management system, allowing the students to work with the models by means of open-source solutions easily, both in asynchronous and face-to-face courses. Consequently, the present approach will improve the application of professional techniques, so the future professionals will reach the working market better prepared.S

Combination of the Photogrammetric and Microwave Remote Sensing for Cultural Heritage Documentation and Preservation– Preliminary Results

Nowadays, cultural heritage is an integral part of modern societies and it is necessary to preserve the tangible and intangible evidences of the past. Cultural heritage objects and sites are being devastated by natural causes and human acts. There are many existing techniques for structural health monitoring, but in the cultural heritage area, there is a need for a non-destructive measurements. The main advantages and drawbacks of some of these technologies have been presented for both laser scanner and photogrammetry techniques. The aim of this article is to present the integration of existing methods for spatial documentation (classical surveying, laser scanner, photogrammetry) and structures health monitoring using electromagnetic spectroscopy. The multi-sensor platform was developed to characterise and analyse various building materials such as marble, sandstone and bricks. The spatial techniques were used for generation of architectural documentation and geolocalisation of the multi-sensor platform. The preliminary results demonstrated that the proposed technology enables commonly used image and rage-based surface measurements as well as measurements through the entire structure for more detailed analysi

AUTOMATIZING DEGRADATION MAPPING OF ANCIENT STELAE BY DUAL-BAND IMAGING AND MACHINE LEARNING-BASED CLASSIFICATION

Degradation patterns are the visible consequence of the impacts of environmental factors and biological agents on stone heritage. Accurately documenting them is a key requisite when studying exposed stone antiquities to interpret weathering causes, identify conservation needs, and plan cleaning interventions. However, a significant gap can be identified in practical automatized procedures for mapping patterns on stone antiquities, such as ancient stelae. This work evaluates a workflow that uses visible and near-infrared imaging, combined with machine learning-based digital image segmentation tools, to classify degradation patterns on marble stelae correctly and cost-effectively. For this work, different classification methods are considered. Results are analyzed using error matrixes and reference degradation maps. The application cases include stelae displayed in the courtyard of the Archaeological Museum of Eretria (Euboea, Greece). The proposed methodology aims at being easily adapted to facilitate the conservators’ work

Review of Surveying Devices for Structural Health Monitoring of Cultural Heritage Buildings

Cultural heritage is the evidence of the past. Nowadays monumental objects create the important part of the cultural heritage, so it is essential to document this type of objects and perform structural health monitoring analysis for preservation. Currently, the digital architectural documentation is recorded as vector drawings, digital object models, 3D models or orthoimages, which are the obligatory form of the inventory of historical objects [1]. In order to generate this type of high resolution and high quality documentation, different sensors as well as appropriate methods are used. The aim of this paper is to present both the conception of the novel surveying device (based on RGB camera, Terrestrial Laser Scanning – TLS with electromagnetic sensor) and methodology of data processing. This paper will review existing state of the art sensors and discuss their advantages and disadvantages as well as the further improvement of such sensors. Additionally, the conception of the new architectural documentation will be described

Geometric analysis on stone façades with terrestrial laser scanner technology

Licensee MDPI, Basel, Switzerland. This article presents a methodology to process information from a Terrestrial Laser Scanner (TLS) from three dimensions (3D) to two dimensions (2D), and to two dimensions with a color value (2.5D), as a tool to document and analyze heritage buildings. Principally focused on the loss of material in stone, this study aims at creating an evaluation method for loss control, taking into account the state of conservation of a building in terms of restoration, from studying the pathologies, to their identification and delimitation. A case study on the Cathedral of the Seu Vella de Lleida was completed, examining the details of the stone surfaces. This cathedral was affected by military use, periods of abandonment, and periodic restorations.Postprint (published version

Multispectral Imaging for the Analysis of Materials and Pathologies in Civil Engineering, Constructions and Natural Spaces

Tesis por compendio de publicaciones[EN] Multispectral imaging is a non-destructive technique that combines imaging and spectroscopy to analyse the spectral behaviour of materials and land covers through the use of geospatial sensors. These sensors collect both spatial and spectral information for a given scenario and a spectral range, so that, their graphical representation elements (pixels or points) store the spectral properties of the radiation reflected by the material sample or land cover. The term multispectral imaging is commonly associated with satellite imaging, but the application range extends to other scales as close-range photogrammetry through the use of sensors on board of airborne systems (gliders, trikes, drones, etc.) or through their use at ground level. Its usefulness has been proved in a variety of disciplines from topography, geology, atmospheric science to forestry or agriculture. The present thesis is framed within close-range remote sensing applied to the civil engineering, cultural heritage and natural resources fields via multispectral image analysis. Specifically, the main goal of this research work is to study and analyse the radiometric behaviour of different natural and artificial covers by combining several sensors recording data in the visible and infrared ranges of the spectrum. The research lines have not been limited to the 2D data analysis, but in some cases 3D intensity data have been integrated with 2D data from active (terrestrial laser scanners) and passive (multispectral digital cameras) sensors in order to analyse different materials and possible associated pathologies, getting more comprehensive products due to the metric that 3D brings to 2D data. Works began with the radiometric calibration of the active and passive sensors used by the vicarious calibration method. The calibrations were carried out through MULRACS, a multispectral radiometric calibration software developed for this purpose (see Appendix B). After the calibration process, active and passive sensors were used together for the discretization of sedimentary rocks and detecting pathologies, as moisture, in façades and in civil structures. Finally, the Doctoral Thesis concludes with a theoretical book chapter in which all the know-how and expertise arising during this research stage have been compiled.[ES]Las imágenes multiespectrales se constituyen como técnica no destructiva que combina imagen y espectroscopía para analizar el comportamiento espectral de distintos materiales y superficies terrestres a través del uso de sensores geoespaciales. Estos sensores adquieren tanto información espacial como espectral para un escenario y un rango espectral dados de tal forma sus unidades de representación gráfica (ya sean píxeles o puntos) registran las propiedades de la radiación reflejada para cada material o cobertura a estudiar y longitud de onda. Las imágenes multiespectrales no solo se limitan a las observaciones satelitales a las que tradicionalmente se vinculan, sino que tienen un campo de aplicación más amplio gracias a los estudios de rango cercano realizados a través del uso de sensores tanto embarcados en sistemas aéreos (planeadores, paramotores, drones, etc.) como a nivel terreno. Su utilidad ha sido demostrada en multitud de disciplinas; desde la topografía, geología, aerología, hasta la ingeniería forestal o la agricultura entre otros. La presente tesis se enmarca dentro de la teledetección de rango cercano aplicada a la ingeniería civil, el patrimonio cultural y los recursos naturales a través del análisis multiespectral de imágenes. Concretamente, el principal objetivo de este trabajo de investigación consiste en el estudio y análisis del comportamiento radiométrico de distintas coberturas naturales y artificiales mediante el uso combinado de distintos sensores que registran información espectral en los rangos visible e infrarrojo del espectro electromagnético. Las líneas de investigación no se han limitado al análisis de datos bidimensionales (imágenes) sino que en algunos casos se han integrado datos de intensidad registrados en 3D a través de sensores activos (láser escáner terrestres) con datos 2D capturados con sensores pasivos (cámaras digitales convencionales y multiespectrales) con el objetivo de analizar diferentes materiales y posibles patologías asociadas a los mismos ofreciendo resultados más completos gracias a la métrica que los datos 3D aportan a los datos 2D. Los trabajos comenzaron con la calibración radiométrica de los sensores por el método de calibración vicario. Las calibraciones fueron resueltas gracias al uso del software MULRACS, un software para la calibración radiométrica multiespectral desarrollado durante este periodo para tal fin (ver Apéndice B). Tras el proceso de calibración, se combinó el uso de sensores activos y pasivos para la diferenciación de distintos tipos de rocas sedimentarias y la detección de patologías, como humedades, en fachadas de edificios históricos y en estructuras de ingeniería civil. Finalmente, la Tesis Doctoral concluye con un capítulo teórico de libro en el cual se recopilan todos los conocimientos y experiencias adquiridos durante este periodo de investigación

3D digitalizacija i vizualizacija kulturne baštine

Informacijske i komunikacijske tehnologije su napravile ogroman pomak u istraživanjima u području humanističkih znanosti, informacijske znanosti su potpuno suživljene sa informacijskim i komunikacijskim tehnologijama. Stoga je digitalizacija u AKM institucijama sasvim prirodan slijed dešavanja, odgovor na društvene i komunikacijske projmene koje su počele još u prošlom stoljeću. Digitalizacija i vizualizacija nepokretnih kulturnih dobara zanimljivo je područje zbog niza faktora koji otežava digitalizaciju a samim tim i vizualizaciju. Konstantno se rađaju nove ideje stvaranja 3D digitalnih modela i prikupljanja informacija (fotografija i oblaka točaka), primjerice terestrički, laserski skeneri koji rade na principu kombiniranja udaljenosti s dva unutarnja kutna mjerenja rotirajućih ogledala skenera, nakon čega se može odrediti sferni koordinatni sustav centriran na skener i bilo koja točka na površini objekta može se snimiti pomoću ovog sfernog koordinatnog sustava. Vizualizacija kulturne baštine svakodnevno odlazi korak dalje za svijetom igrica, te kombiniranjem stvarnosti, virtualne stvarnosti i proširene stvarnosti kreira sasvim nova iskustva za korisnika.Information and communication technologies have made a huge breakthrough in research in the field of humanities, information science is fully involved in information and communication technologies. Therefore digitization in AKM institutions is a very natural sequence of events, the response to social and communication projects that started in the last century. Digitization and visualization of architectural heritage is an interesting area due to a number of factors that make digitization difficult and with team and visualization. Constantly creating new ideas for creating 3D digital models and collecting information (photos and point clouds), eg terrestrial laser scanners working on the principle of combination of distance with two internal angular measurements of rotating reflecting scanners, after which a functional coordinate system centered on the scanner can be determined any point on the surface of the object can be recorded using this punctual coordinate system. Visualization of cultural heritage goes on to the world of gaming every day, combining reality, virtual reality and expanded reality creates a whole new experience for the users

Multispectral Radiometric Analysis of Façades to Detect Pathologies from Active and Passive Remote Sensing

This paper presents a radiometric study to recognize pathologies in façades of historical buildings by using two different remote sensing technologies covering part of the visible and very near infrared spectrum (530–905 nm). Building materials deteriorate over the years due to different extrinsic and intrinsic agents, so assessing these affections in a non-invasive way is crucial to help preserve them since in many cases they are valuable and some have been declared monuments of cultural interest. For the investigation, passive and active remote acquisition systems were applied operating at different wavelengths. A 6-band Mini-MCA multispectral camera (530–801 nm) and a FARO Focus3D terrestrial laser scanner (905 nm) were used with the dual purpose of detecting different materials and damages on building façades as well as determining which acquisition system and spectral range is more suitable for this kind of studies. The laser scan points were used as base to create orthoimages, the input of the two different classification processes performed. The set of all orthoimages from both sensors was classified under supervision. Furthermore, orthoimages from each individual sensor were automatically classified to compare results from each sensor with the reference supervised classification. Higher overall accuracy with the FARO Focus3D, 74.39%, was obtained with respect to the Mini MCA6, 66.04%. Finally, after applying the radiometric calibration, a minimum improvement of 24% in the image classification results was obtained in terms of overall accuracy

Implicaciones de la fotogrametría y de las técnicas láser en la identificación y caracterización de las trazas antrópicas sobre restos óseos en los yacimientos arqueológicos del pleistoceno

Tesis por compendio de publicaciones[ES] La tafonomía durante las últimas décadas ha demostrado ser una disciplina de gran relevancia para la explicación e interpretación de los yacimientos arqueológicos y paleontológicos. La tafonomía es una disciplina que permite proponer diferentes tipos de soluciones a los diversos problemas interpretativos encontrados en los yacimientos arqueológicos. A través de la experimentación y de su enfoque analógico deductivo permite proponer hipótesis explicativas. Durante los últimos años el análisis de las marcas de corte ha generado una gran expectación. Este tipo de trazas están asociadas a la acción humana y pueden resultar de gran importancia para explicar el comportamiento de las poblaciones prehistóricas. De este modo, las marcas de corte resultan ser una herramienta clave en la explicación del debate caza-carroñeo, y pueden ayudar a explicar qué pasos se siguen en el procesado de una carcasa animal. Es relevante también el análisis de las marcas de corte en relación a la selección de las materias primas con las que fueron realizadas dichas marcas, en cuanto al aprovechamiento de las carcasas. Por lo tanto, es crucial, la definición correcta y la información obtenida de estas y también la realización de una identificación de los materiales utilizados en el proceso de aprovechamiento de los animales. Desde finales del siglo XIX, los investigadores toman conciencia de la relevancia que puede tener el estudio de las alteraciones que aparecen sobre los huesos, catalogándolas en un primer momento de forma descriptiva. A raíz de la irrupción de la tafonomía en la investigación arqueológica, algunos investigadores han tratado de discriminar las distintas clases de marcas que aparecen en los huesos, experimentando con diferentes métodos para observar mejor las marcas de corte. En la actualidad, la metodología más utilizada, se basa en la aplicación de técnicas microscópicas usando para estas investigaciones microscopios electrónicos de barrido (Scanning Electron Microscope - SEM). En estos últimos años, los investigadores, a partir de estas técnicas, han sido capaces de lograr resultados espectaculares gracias a las mediciones tridimensionales que han podido obtener de las marcas de corte en huesos. La documentación 3D de las marcas de corte con estas técnicas microscópicas obtiene muy buenos resultados, pero también plantea diferentes inconvenientes: utiliza equipos económicamente muy costosos, en muchos casos las muestras necesitan de una preparación antes de realizar el proceso, sólo técnicos especialistas en el campo pueden realizar un manejo óptimo del instrumento y por último su principal inconveniente, es que es un equipo fijo de trabajo, por lo que no se puede desplazar hasta el yacimiento arqueológico. Con el fin de resolver todas estas problemáticas y con el objetivo de mejorar la metodología ampliando el volumen de los datos susceptibles de ser analizados, en esta Tesis Doctoral se explica el uso de la fotogrametría y de la visión computacional para llevar a cabo estos estudios. Más concretamente, se describe el proceso de captura de datos, el procesado de los mismos y los análisis estadísticos y morfométricos realizados a los datos resultantes obtenidos a partir de estas técnicas. Para realizar este estudio, se han llevado a cabo varios cientos de siluetas de marcas de cortes experimentales en huesos y en fósiles, realizados con diferentes materias primas (sílex, basalto, cuarcita y metal). Esta muestra constituye una de las mayores bases de datos de este tipo recopiladas hasta el día de hoy. Por último, se sugieren nuevas líneas de investigación a las que este procedimiento podría ser fácilmente aplicable