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Pindal Cave in Asturias reconstructed in 3D.

Pindal cave, listed as World Heritage by UNESCO since July of this year, can tour in 3D thanks to a research by a team of professors at the Polytechnic School of Avila, who heads Diego González Aguilera.

This team, known as Tidop Research Group (Information Technology for Heritage Documentation) just completed under the supervision of Professor Mario Menéndez, Department of Prehistory and Archaeology at UNED, its comprehensive documentation and metric 3D reconstruction.
But what is the real importance of this work? “The determination of the geometric component in the accurate documentation of the heritage involves the quantification of the special characteristics of the object, especially its shape and dimensions, orientation and location”, profesor González Aguilera explains, “and this operation becomes important in the sense that their results may become the basis for reconstruction and is also a testimony of the prior state to any intervention or modification.”
Pindal cave stands in the vicinity of the town of Pimiango in Ribadedeva (Asturias), near the border with Cantabria. This beautiful corner is well known for some cave paintings discovered in 1908.

Terrestrial laser scanner

Recently, the use of terrestrial laser scanner, used in researchs, enables a new approach to the problem of documentation and three-dimensional geometric modeling of the Paleolithic caves and parietal art. According to the studio manager says, this is the land Trimble GX scanner mounted on the Manfrotto 400 swivel that allows spins with three degrees of freedom, necessary to accommodate the position of the scanner to the characteristics of the cave. “The data captured by this team is finally summarized the three-dimensional XYZ coordinates of mesh points and their radiometric values in RGB color system,” points out the technical details González Aguilera.
Basically this laser and two high resolution digital cameras were the tools needed to carry out the fieldwork. “The field work was conducted for five alternate days. They included five members of the group Tidop aided by two operators of the Council.
“Thus it was possible to combine the laser scanning and the photo shoot,” says González Aguilera, further explains that, given the complexity of the geometry inside the cave and the problems caused by occlusions, both for laser scans as for photographic archive was necessary to make a total of 19 laser stations, from which they made general scans of 360º with mesh steps of 2 centimeters in 20 meters, and two shots per point.
“This data collection configuration ensured more than 15% of overlapping between the point clouds obtained, thereby having a guarantee for proper fusion of the point clouds”, says the professor of the Polytechnic. In fact, a total of 33 million points in XYZ coordinates were obtained for the geometrical definition of the interior of the cavern.
On the other hand were the photo sessions that involved two different types of work: a set of shots to complete the work of the laser, through the ability to provide high-resolution photographic texture to the point cloud, and another set of shots with the fisheye lens for the generation of linked panoramas that allow us to generate a virtual visit. For this 25 photographic stations were chosen from which we made the seven necessary shots to compose each of the 25 panoramas.

Computer processing

After the processing of all the data the team obtained a ground orthophoto. “It shows a top view of the cave, which can be considered as a precise and detailed plan of the cave”, begins to list his conclusions Professor González Aguilera. Furthermore, orthophotos of the cave paintings room and a textured 3D model were obtained. “This is an interactive model through which you can navigate, retaining the metric properties and being able to see the object from inaccessible points of view,” says the teacher, pointing this advantage of the system.
Diego González Aguilera explains that from the data obtained has been possible to draw another set of tools and applications that have resulted in obtaining virtual flights, that is, a number of video files generated from the laser three-dimensional models, as well as a virtual tour that has been generated by coherent composition of the whole panoramic photographs taken before and also has been able to generate transverse and longitudinal sections of the cave. With this work done in the environment that will, among other things, better and wider dissemination of the cave is complete. With this the work is completed and it will allow, among other things, a better and wider dissemination of the cave.

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Análisis termográfico de edificios

 

El uso de la termografía infrarroja comMapaEnergeticoo técnica sobradamente provada para la inspección de edificios y localización de patologías como fugas de aire, humedades, etc. Nos permite realizar un examen visual “in-situ” de calidad de los objetos de estudio gracias a la posibilidad de visualizar en tiempo real los resultados pudiendo detectar sin dificultad los desperfectos o elementos característicos de estos. Estas técnicas de medición cualitativa nos proporcionan la posibilidad de realizar inspecciones rápidas y eficaces sin contacto directo con el objeto y de forma no destructiva, lo que disminuye tanto el riesgo de incidentes para los operarios como los daños producidos en los propios objetos de estudio ocasionados por otras técnicas intrusivas. Además, también se ha demostrado la utilidad de la termografía infrarroja como técnica puramente de medida a través de su utilización para el cálculo de propiedades termofísicas de materiales tales como difusividad y transmitancia térmica.

En el caso de termografía cualitativa, las publicaciones existentes tratan de estudios realizados in-situ, principalmente en edificios históricos o elementos del patrimonio cultural, mientras que los estudios cualitativos se realizan, en la mayor parte de los casos, en laboratorios sobre muestras de tamaño limitado. En aquellos casos en los que se han realizado estudios termográficos cuantitativos sobre edificios in-situ, los valores de temperatura son empleados con el objetivo de obtener propiedades termofísicas (conductancia térmica) reales del cerramiento, sin embargo su distribución espacial no es considerada.

Conjugar ambas aplicaciones permitirá la automatización del cálculo de pérdidas de calor a partir de las temperaturas medidas con una cámara termográfica. De este modo, no solo se usa la termografía para representar el estado de la pared, sino que también se usan los valores de temperatura contenidos en la termografía para la extracción de parámetros métricos del edificio en estudio, por lo que la hibridación de la información termográfica con el material cartográfico de precisión permitiría extraer la geometría real del objeto de estudio con textura termográfica, pudiendo así realizar mediciones precisas de los elementos de interés directamente sobre el resultado obtenido.

 

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Estudios como el publicado por EuroACE en 2010 colocan la mejora de la eficiencia energética en edificación en cabeza de las acciones necesarias para la reducción de emisiones de gases del efecto invernadero y gasto energético, así como para servir de empuje a la generación de empleo. Especial es el caso del parque de edificios ya construidos, la mayoría procedente de los años 1940-80, con normativa inexistente y recursos escasos. En ellos las obras de rehabilitación energética pueden suponer un ahorro de hasta el 75% en consumo de energía. En España existen 13 millones de viviendas susceptibles de intervención, cuya rehabilitación energética supondría una reducción de las emisiones del sector del 34% con respecto al año 2001.

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Building thermographic analysis

 

 

The use of infraMapaEnergeticored thermography as a widely tested technique for building inspection and location of pathologies such as air leakage and moisture allows the performance of  quality “in-situ” visual examination of the objects under study due to the possibility of obtaining real-time results, being able to detect without difficulty damages or material characteristics. This qualitative measurement technique provides the capability of doing quick, effective and non-destructive inspection without direct contact with the object under study, decreasing the risk of incidents to operators and the damage of the objects comparing with other intrusive techniques. Furthermore, the utility of infrared thermography as a measurement technique has been proved by its use for the determination of the thermophysical properties of materials such as diffusivity and thermal transmittance.

In the qualitative approach, some authors have performed in-situ studies, mainly in historical buildings or cultural heritage elements, whereas quantitative studies are performed mainly in laboratories with limited size samples. In those cases where quantitative thermography studies were performed in-situ, temperature values were employed in order to obtain the real thermophysical properties (thermal conductance) of the building envelope, but their spatial distribution is not considered.

Combine both applications will enable the automation of the heat loss computation from the measured temperatures with a thermographic camera. Thus, the thermography is not only used to represent the state of the wall, but also temperature values represented on the thermography for extracting the metric parameters of the study object so the hybridization of the thermographic information with precise cartographic material would  allow to extract the actual geometry of the object of study with thermal texture, being able to make accurate measurements of the elements of interest directly on the obtained results.

 

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Studies such as the one published by EuroACE in 2010, places improved energy efficiency in building construction at the top of the list of actions that need to be taken to reduce greenhouse gases and energy costs, in addition to acting as a stimulus to generate employment. In particular is the case of existing buildings stock, most of which dates back to the period 1940-80, constructed using non-existent standards and scarce resources. Here, energy refurbishment works could represent a saving of up to 75% in energy consumption. In Spain there are 13 million homes that could be the subject of intervention, where energy refurbishment could result in a reduction in sector emissions of 34% compared to 2001.

 

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Mobile Laser System (MLS) applied to urban tree inventory

In urbanized Western Europe trees are considered an important component of the built-up environment. This also means that there is an increasing demand for tree inventories. Laser mobile mapping systems provide an efficient and accurate way to sample the 3D road surrounding including notable roadside trees. In this research line, a processing chain aiming at the extraction of tree locations and tree sizes from laser mobile mapping data is reached.

  • Vegetation extraction

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  • Tree parameter extraction

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Such steps, in combination with code optimization are expected to be sufficient to reach the final goal of automatized estimation of features sampled by mobile mapping at a rate that matches the acquisition speed and at a quality that matches the result of a human operator.

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Miembro del grupo TIDOP

Lloyd A. Courtenay

Graduado en arqueología por la Universidad Complutense de Madrid. Actualmente está acabando un Máster en Arqueología del Cuaternario y Evolución Humana por la Universidad Rovira i Virgili, Tarragona, con el objetivo de seguir con su formación investigadora matriculándose en un programa de Doctorado en prehistoria para el próximo año académico. Habiéndose especializado en el campo de la tafonomía, trabaja principalmente en el estudio microscópico de los restos óseos que aparecen en los yacimientos arqueológicos y paleontológicos. Su principal campo de investigación está dirigido hacia la aplicación de nuevas metodologías en yacimientos del Pleistoceno Inferior Africano. En los últimos años ha emprendido su carrera profesional adaptando los nuevos avances estadísticos en otros campos como la Inteligencia Artificial, buscando maneras de aplicarlos al estudio del registro fósil. Siguiendo esta línea de investigación, ha conseguido desarrollar una serie de algoritmos aplicando métodos de Machine y Deep Learning para el procesado de datos derivados de modelos 3D. Con el diseño de algoritmos complejos como las Redes de Neuronas Artificiales y las Máquinas de Vectores de Soporte, ha desarrollado nuevos modelos estadísticos que pueden distinguir entre la actividad de diferentes carnívoros a través de las marcas de dientes que dejan. Estos modelos permiten también la clasificación de las alteraciones microscópicas halladas como producto de agentes naturales o por el contrario, si fueron consecuencia de las actividades de caza de los antiguos homínidos.

Líneas de investigación:

  • Tafonomía y zooarqueología aplicado al estudio del Pleistoceno Inferior
  • Desarrollo de nuevos métodos para el estudio microscópico de los restos fósiles
  • Diseño y aplicación de nuevos métodos estadísticos en la arqueología, incluyendo la aplicación de técnicas 3D para la documentación de restos óseos, y el uso de algoritmos de Inteligencia Artificial para procesar tales datos
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TIDOP Member

Lloyd A. Courtenay

An Archaeology graduate having studied in the Complutense University of Madrid, he is currently finishing his Master’s degree in Quaternary Archaeology and Human Evolution in the University Rovira I Virgili, Tarragona. Starting next academic year, he intends to continue his professional career by enrolling in a Doctoral programme in prehistory. Specialised in the field of taphonomy, he works primarily on the microscopic study of osteological materials found in archaeological and paleontological sites. His main field of research lies in the development of new methods for the study of Lower Pleistocene sites in Africa. Over the last couple of years, he has focused his research on the adaptation of new statistical advances from other fields of research, such as Artificial Intelligence, with the hope of finding new means of applying these techniques to the prehistoric fossil register. Through this line of research, he has achieved the development of Machine and Deep Learning algorithms for the processing of 3D data. His most notable advances have included the development of Artificial Neural Networks and Support Vector Machines for the differentiation of carnivore activity through the tooth marks animals may leave on bone. He has also achieved models that are able to successfully classify microscopic traces, discerning between natural agents and those produced by ancient hominids in prehistoric butchery practices.

Research lines:

  • Taphonomy and zooarchaeology applied to the Lower Pleistocene
  • Development of new methodological approaches for the study of fossil remains
  • Design and application of new statistical models for archaeological studies, including 3D modelling for the documentation of bone, and the use of Artificial Intelligence algorithms for the processing of this data
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Drones terrestres aplicados al modelizado tridimensional e inspección de infraestructuras críticas y de difícil acceso.

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Equipar drones con sensores láser, detectores de obstáculos y sistemas de control remoto permite obtener de forma segura y fiable los modelos tridimensionales de escenarios críticos, entendiendo como escenarios críticos todos aquellos escenarios en los que una persona correría peligro realizando los trabajos.

Este tipo de escenarios abarcan desde grutas angostas y estrechas a las que es difícil acceder, hasta escenarios industriales complejos, como subestaciones eléctricas, en las que existen riesgos de descargas eléctricas, salas de calderas, edificios con problemas estructurales etc.

A pesar de ser lugares críticos, su mantenimiento e inspección es un aspecto clave en el campo del control preventivo de averías y deformaciones, por lo que obtener el modelo tridimensional de estos lugares es fundamental. En este sentido, los drones terrestres, cada vez más sofisticados, permiten integrar escáner láser terrestre para capturar el entorno, asi como detectores de obstáculos y diferentes sistemas de comunicación, de modo que pueden moverse de forma autónoma o ser teledirigidos de forma remota.

Hasta el momento se ha investigado la integración de drones terrestres y escáner láser utilizando dos metodologías de trabajo diferentes, según el grado de precisión y detalle que se necesite y dependiendo de las dimensiones del espacio en el que se esté trabajando.

 

Finalmente, se está investigando la manera de combinar los modelos tridimensionales obtenidos por los drones terrestres con datos procedentes de drones aéreos equipados con cámaras fotográficas o cámaras termográficas. Combinar ambos modelos es esencial para obtener una cobertura total de la escena de estudio y poder detectar anomalías en cualquier lugar. Ésta línea de acción se está introduciendo para controlar subestaciones eléctricas y plantas solares fotovoltaicas ya que en ambos casos es posible detectar zonas con un calentamiento anormal que indiquen un funcionamiento que deberá revisarse.

 

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Land drones applied to three-dimensional modeling and control of complex industrial environments

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Land drones can be armed with different devices such as terrestrial laser scanner, obstacle detectors or remote control systems, in order to provide accurate 3D models of unattended or critical environments in a safe way.

Environments like narrow caves that are difficult to access, electrical substations where there are risk of electric shock, boiler rooms or buildings with structural problems are considered critical environments for human operators due to the danger they entail.

Despite being critical spaces, its maintenance, inspection and control are essential to prevent damages and detect breakdowns, so accurate three-dimensional models are indispensable. For this purpose, terrestrial drones allow the integration of terrestrial laser scanners to capture the environment, as well as obstacle detectors and different communication systems, so that they can be autonomous vehicles or remote-controlled vehicles.

Depending on the accuracy needed and the dimensions of the study case, two different  combinations of technologies have been explored, both combining laser scanner with land drones.

To complete this research line, we are working in different methodologies to combine 3D models obtained with land drones and data obtained with aerial drones equipped with conventional cameras or thermo graphic cameras.

Mix both kind of models make the three-dimensional model much more complete and it is possible to detect pathologies in almost everywhere.  Some of this process has been used with success in electrical substations and photovoltaic solar plants, detecting, for example, anomalies in some panels.

 

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