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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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Ventana modal ingles
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Ventana modal español
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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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