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Indentifying the Heritage´s wounds

A PhD student of the University of Salamanca develops a low cost methodology to evaluate, in a rigorous way, pathologies in façades and constructions without contact and through new sensors and technologies.

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Buildings, environments, sculptures, ruins, churches, murals, museums, paintings or streets,  they are living testaments of the humanity and form the most value heritage of the present and future. However, despite of their value, many of them present pathological processes (wounds) as a result of several factors such as degradation over time or due to human activity.

To avoid this situation Susana del Pozo, a PhD student of the University of Salamanca, is engaged in a project that attempts to develop a low-cost methodology able to detect “in a rigorous way” the pathologies of façades and civil constructions. Without contact with them and by using new sensors and technologies.

In this way, multispectral imaging is placed as a feasible no-destructive solution. By contrast to other inspection protocols in civil engineering and cultural heritage fields. This method requires as input espectral information from passive systems (digital or multispectral cameras) or active systems (like the Terretrial Laser Scanners), operating in the infrared spectrum. “These devices can capture the reflected light from materials, and if these proprortion of light is known, it is possible to evaluate pathologies of them”, explains Susana.  Therefore, the challenge is to transform the output digital signal of each sensor in its corresponding physical value of reflectance. This process is commonly known as radiometric calibration.

In this project, Susana has used a low-cost sensor: a multispectral camera with six channels, several canvas and color vinyls (used as control surfaces) and natural surfaces/materials (as check surfaces). Furthermore, an self-developed software called MULRACS has been used to assist in the calibration process. “MULRACS allows the transformation of images from any kind of sensor to reflectance values through an intuitive interface and data processing”, claims Susana.

Nowadays, routine inspections of such buildings are mainly visual, involving subjective results. Taking this into account, the develop of new methodologies able to evaluate building pathologies in a rigorous and remote way, are a key for the correct maintenance of such constructions, particularly in areas that are more exposed to degradation agents.

The combination of a low cost hardware-software makes this methodology “unique” in the market. It allows performing different studies and analysis materials, opening new possibilities for different disciplines relating with conservation and constructions. The main advantage of the methodology lies in the possibility of capture geometric and radiometric information at the same time, allowing the quantification of the detected pathologies.

This approach is based on the interaction between the energy and the construction´s materials. In particular, the methodology evaluates the reflected light for each of the wavelenghts of the electromagnetic spectrum. Finally, the so called “spectral signature” of each material is obtained.

In this way, Susana del Pozo uses several devices -passive and active sensors- with the aim of capturing the reflected radiation from materials of historic façades and civil infrastructures, for wich a correct planning is crutial to obtain quality results.

The added value of this project, which starts in September of 2011 and is linked to her Doctoral Thesis, is the cost saving, investing in low cost and flexible methodologies, in which aerial platforms such as UAVs or paramotors can be used flying at moderate heights, for which atmospheric effects are negligible.

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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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