Optimization of Photogrammetric Flights with UAVs for the Metric Virtualization of Archaeological Sites. Application to Juliobriga (Cantabria, Spain)

ABSTRACT: Three-dimensional models are required to virtualize heritage sites. In recent years, different techniques that ease their generation have been consolidated, such as photogrammetry with Unmanned Aerial Vehicles (UAVs). Nonmetric cameras allow relatively inexpensive data collections. Traditional aerial photogrammetry has established methodologies, but there are not commonly used recommendations for the selection of parameters when working with UAV platforms. This research applies the Taguchi Design of Experiments Method, with four parameters (height of flight, forward and lateral overlaps, and inclination angle of the sensor) and three levels (L9 matrix and nine flights), to determine the set that offers the best metric goodness and, therefore, the most faithful model. The Roman civitas of Juliobriga (Cantabria, North of Spain) was selected for this experiment. The optimal flight results of the average signal-to-noise ratio analysis were height of 15 m, forward and lateral overlaps of 80%, and inclination of 0° (nadiral). This research also highlights the noticeable contribution of the inclination in the accuracy of the model with respect to the others, which is 16.4 times higher than that of the less relevant one (height of flight). This leads to propose avoiding inclination angle as a variable, and the sole development of nadiral flights to obtain accurate models

Metric contrast of thermal 3D models of large industrial facilities obtained by means of low-cost infrared sensors in UAV platforms

Monitoring for maintenance or studies of energy efficiency in buildings, large infrastructure, industrial facilities, etc., are common nowadays. These kind of studies are developed with inspections which determine the state of the facilities that are analysed. The difficulty is increased along with the size and complexity of the facility itself, and even more when the attribute to be surveyed is not noticeable or responsive for the human eye. In recent years, a series of techniques that rely on different sensors mounted on UAVs allow detecting problems that are associated with facilities of large dimensions. Almost all of them work in the visible band (RGB), but the generation of thermal 3D models permits detecting any heat anomaly related to the functioning of these facilities. This research proposes a methodology and workflow for the generation and Metric Contrast of Thermal Models (MCTM). This methodology is metrically applied to a mining-industrial facility in which thermal conditions have great influence for a proper functioning. For this metric contrast, several distances have been measured in the field and compared to those obtained from the models. The average difference between the true magnitude and those obtained from the RGB and thermal models are 5 and 31 cm, and their standard deviations are 7 and 29 cm, respectively. The comparison between the RGB and the thermal model provides an average distance between points is 0.19 m, and for 75% of the points the distance is lesser than 0.35 m. Although the RGB model is more accurate, the precision of the thermal model is enough for the objectives se

Mining exploration with UAV, low-cost thermal cameras and GIS tools. Application to the specific case of the complex sulfides hosted in carbonates of Udías (Cantabria, Spain)

The depletion of natural resources implies the need for a constant search for new reserves to satisfy demand. In the mining sector, Unmanned Aerial Vehicles (UAVs) have revolutionised geo-information capture and modelling to allow the use of low-cost sensors for prospecting and exploration for potentially exploitable resources. A very powerful alternative for managing the huge volume of data is the Geographic Information System (GIS), which allows storage, visualisation, analysis, processing and map creation. The research in this paper validates a new quasi-automatic identification of mining resources using GIS thermal-image analysis obtained from UAVs and low-cost sensors. It was tested in a case that differentiated limestone from dolostone with varying iron content, and different thermal behaviour from solar radiation, thereby ensuring that the thermal image recorded these differences. The objective is to discriminate differences in an image in a quasi-automatic way using GIS tools and ultimately to determine outcrops that could contain mineralisation. The comparison between the proposed method with traditional precision alternatives offered differences of only 4.57%, a very small deviation at this early stage of exploration. Hence, it can be considered very suitabl

4D models generated with UAV photogrammetry for landfill monitoring thermal control of Municipal Solid Waste (MSW) landfills

The management of the increasing volume of municipal solid waste is an essential activity for the health of the environment and of the population. The organic matter of waste deposited in landfills is subject to aerobic decomposition processes, bacterial aerobic decomposition, and chemical reactions that release large amounts of heat, biogas, and leachates at high temperatures. The control of these by-products enables their recovery, utilization, and treatment for energy use, avoiding emissions to the environment. UAVs with low-cost thermal sensors are a tool that enables the representation of temperature distributions for the thermal control of landfills. This study focuses on the development of a methodology for the generation of 3D thermal models through the projection of TIR image information onto a 3D model generated from RGB images and the identification of thermal anomalies by means of photointerpretation and GIS analysis. The novel methodological approach was implemented at the Meruelo landfill for validation. At the facility, a 4D model (X,Y,Z-temperature) and a 13.8 cm/px GSD thermal orthoimage were generated with a thermal accuracy of 1.63 °C, which enabled the identification of at least five areas of high temperatures associated with possible biogas emissions, decomposing organic matter, or underground fires, which were verified by on-site measurements and photointerpretation of the RGB model, in order to take and assess specific corrective measures.The authors wish to express their gratitude to the “Concepción Arenal” Grant Programme of the University of Cantabria and to the Government of Cantabria for the financial support provided for the development of the research activities. Grant Number: UC-20-41

Optimal location of solar photovoltaic plants using Geographic Information Systems and multi-criteria analysis

Nowadays, solar energy is considered to be one of the most developed renewable energy sources, and its production capacity has increased in recent years. To optimize yields and production, the correct selection of the location of these plants is essential. This research develops a methodological proposal that allows for detecting and evaluating the most appropriate places to implement solar photovoltaic plants almost automatically through GIS tools. A multi-criteria analysis is proposed to analyze large extensions of land with ten duly weighted criteria that cover the energy and territorial requirements that any installation must meet. The method assigns each site a location coefficient that reflects the weighting of the chosen criteria so that the value ordered from highest to lowest reflects the best to the worst location. Unlike other research works that can be considered similar, the methodological proposal is much more consistent than traditional alternatives as it uses a multi-criteria analysis and a weighting mechanism that is also statistically consistent, objective, and based on logical criteria. This innovative methodology is applied to Cantabria (north of Spain), although it could be used for other contexts

Implementación de un SIG en el entorno del transporte de pasajeros

Grado en Ingeniería de los Recursos Energético

Geometric and thermal modeling with low-cost unmanned aerial vehicles for mining applications

La fotogrametría y los modelos tridimensionales han sido revolucionados por los vehículos aéreos no tripulados (UAV). Estos equipos permiten la captura de imágenes con diferentes sensores de bajo coste, como cámaras RGB y térmicas. Comprender la respuesta radiométrica de los sensores y él método fotogramétrico es esencial para crear modelos 3D térmicos que representen la posición, geometría y temperatura en cada punto del modelo. La presente Tesis aborda la falta de metodologías para la generación de modelos 3D geométricos y térmicos y su aplicación en minería. La investigación se centra en el desarrollo de una metodología basada en la combinación de imágenes RGB y térmicas capturadas por UAV de bajo coste para la generación e implementación de los modelos en minería, la cual se valida a través de cuatro experimentos. El primer experimento evalúa las limitaciones de los sensores RGB de bajo costo en la generación de modelos. El segundo experimento analiza la precisión de los modelos térmicos. El tercer y cuarto experimento se aplica la metodología propuesta demostrando su eficacia en la identificación de litologías y recursos hidrotermales. Esta metodología tiene un gran potencial en la industria minera y otras aplicaciones geofísicas.Photogrammetry and three-dimensional modeling have been revolutionized by unmanned aerial vehicles (UAVs). This equipment allows the capture of images with different low-cost sensors, such as RGB and thermal cameras. Understanding the radiometric response of the sensors and the photogrammetric method is essential to create 3D thermal models that represent the position, geometry and temperature at each point of the model. This thesis addresses the lack of methodologies for the generation of 3D geometric and thermal models and their application in mining. The research focuses on the development of a methodology based on the combination of RGB and thermal images captured by low-cost UAV for the generation and implementation of models in mining, which is validated through four experiments. The first experiment evaluates the limitations of low-cost RGB sensors in model generation. The second experiment analyzes the accuracy of thermal models. The third and fourth experiments apply the proposed methodology demonstrating its effectiveness in the identification of lithologies and hydrothermal resources. This methodology has great potential in the mining industry and other geophysical applications

Thermal control in mining processing plants using three-dimensional thermal models obtained with drones

RESUMEN: El paso del tiempo, los efectos climáticos y las actividades desarrolladas contribuyen a la degradación y afección de las estructuras. La conservación y mantenimiento en condiciones óptimas, requiere del control y seguimiento de edificios de acuerdo a la Ley de Ordenación de Ordenación de la Edificación (LOE). La evolución y valoración del estado estructural dentro del ámbito de la Inspección Técnica del Edificio (ITE) de forma tradicional, se realiza en base a una inspección visual por un técnico competente. Sin embargo, esta concepción convencional se ve afectada por la irrupción de vehículos aéreos no tripulados (UAVs), comúnmente conocidos como drones, equipados con sensores aéreos, cámaras métricas y multiespectrales para la captura de información e imágenes a partir de las cuales desarrollar las evaluaciones e inspecciones. La reciente incorporación de los UAVs en las múltiples facetas de la ingeniería, supone la ausencia de metodologías para su implementación el ámbito de las inspecciones estructurales. Hecho que se magnifica cuando se trata de valoraciones del comportamiento térmico de infraestructuras. Lo que deriva en el objetivo fundamental del presente TFM, la investigación y desarrollo de una metodología de trabajo que sea capaz de integrar las plataformas UAV, los sensores métricos y multiespectrales para generar modelos métricos/térmicos de infraestructuras a inspeccionar o monitorizar geométricamente. De este objetivo se derivan una serie de hitos que deben alcanzarse para la consecución del objetivo: A. Conocimiento y formación en los distintos campos de la ciencia intervinientes, como son la edificación, fotogrametría, termografía y las plataformas UAV. B. Diseño y planificación de los vuelos UAVs, estudiando la optimización de los en vuelos en base a los parámetros de diseño. C. Diseño de la metodóloga y procesado de la información e imágenes obtenidas que permita el dimensionamiento y modelado métrico de la patología a evaluar. D. Desarrollo y validación de una metodología de trabajo innovadora que permita alcanzar el objetivo. Los UAVs de acuerdo a sus siglas en ingles quiere decir Unmanned Aerial Vehicle, que traducido al castellano significa Vehículo Aéreo No Tripulado (VANT). A pesar de que la utilización de las aeronaves no tripuladas a gran escala es relativamente reciente, está teniendo un rápido desarrollo en multitud de campos ingenieriles. La termografía se puede definir como una metodologia fisica no destructiva que permite la medicion y visualización de temperaturas de superficies con gran precision, basándose en la medición de la radiacción infrarroja emitida por los cuerpos. El resultado de la termografia son mapas térmicos o imágenes termográficas, que representan la distribución térmica de la superficie observada. Constituyendo una herramienta complementaria en las actividades de inspección estructural. Control térmico en plantas de beneficio minero mediante modelos térmicos tridimensionales obtenidos con drones En última instancia, la fotogrametría se puede definir como técnica que permite definir la geométrica y posicionamiento de objetos a partir de mediciones realizadas sobre fotografías de los mismos. La consecución de modelos tridimensional y la obtención de información cuantitativa a partir de imágenes se apoya en el método general de la fotogramétrica, el cual busca reproducir mediante 4 pasos la visión estereoscópica, principio en el cual se basa la capacidad de los seres humanos para percibir el relieve de las cosas. Basándose en estos tres pilares y el apoyo de herramientas informáticas, en primera instancia se realizó un análisis del dimensionamiento de proyectos de vuelo tomando como zona de estudio el Campus Universitario de Torrelavega, para la optimización de la captación de imágenes RGB y térmicas en base a una serie de criterios establecidos que buscaban optimizar el tiempo y volumen de trabajo. Alcanzo de esta manera una serie de recomendaciones estándares para el dimensionamiento de los vuelos realizados bajo la metodología de trabajo propuesta. En la segunda fase se desarrolló un procedimiento de integración y tratamiento de las imágenes térmicas, analizando las alternativas propuestas por diversos autores y las particulares de este tipo de imágenes. La metodología que se propone implica trabajar con imágenes combinadas o fusionas, que son una interpolación entre la imagen RGB y la térmica de la superficie fotografiada, procesando el conjunto de imágenes según el flujo de trabajo convencional que se aplica a las imágenes RGB en la confección de modelos tridimensionales. El conjunto de procedimiento alcanzados es materializado y contrastado con la implementación del método en una planta de beneficio minero como las instalaciones de Cementos ALFA S.A. en la localidad de Mataporquera. Donde se procedió a realizar el modelado tridimensional de la totalidad de la planta, además del silo y la chimenea de forma independiente, como estructuras representativas sobre las cuales potenciar la calidad del resultado obtenido. Las actividades realizadas consistieron en la realización de dos vuelos, uno general de la totalidad de la instalación según las recomendaciones establecidos, y un segundo vuelo de detalle perimetral envolvente para cada una de las dos estructuras mencionadas tomando imágenes térmicas y RGB. A partir de las fotografías captura y mediante el software Agisoft se generaron modelos tridimensionales a partir de las imágenes RGB y las combinadas obteniendo diversos modelos en función de la georreferenciación implementada en cada caso. Los modelos resultantes son contrastados y validados mediante la comparación de puntos de control y mediciones de distancias, áreas y volúmenes, permitiendo de esta manera determinar la precisión alcanzada y las desviaciones existente respecto a la realidad. En definitiva, el conjunto de actividades realizadas en el presente TFM logra la implementación de una metodología para el dimensionamiento de vuelos fotogramétricos y el posterior tratamiento que permite la obtención de modelos 3D RGB y térmicos a partir de imágenes obtenidas mediante sensores integrados en plataformas UAV, a partir de los cuáles se puede obtener información térmica cualitativa e información métrica cuantitativa.ABSTRACT: The passage of time, climatic effects and activities contribute to the degradation and structural damage. The conservation and maintenance in optimal conditions requires the control and monitoring of buildings acording to Ley de Ordenación de Ordenación de la Edificación (LOE). The evolution on terms of the Technical Building Inspection (ITE) in a traditional way, is carried out based on a visual inspection by a competent technician. However, this conventional conception is affected by the irruption of unmanned aerial vehicles (UAVs), commonly known as drones, equipped with aerial sensors, metric and multispectral cameras to capture information and images which to allows evaluations and inspections. The recent incorporation of UAVs in the multiple facets of engineering, supposes the absence of methodologies for their implementation in the structural inspection. This is magnified when it comes to evaluations of the thermal behavior of infrastructures. Which derived into the main objective of this TFM, the research and development of a methodology capable of integrate UAV platforms, metric and multispectral sensors to generate metric / thermal models of infrastructures to inspect or monitor geometrically. From this objective a bunch of milestones are derived which must be overcome to achieve the objective: A. Acquisition of the knowledge and training in the different fields of science involved, such as structures, photogrammetry, thermography and UAV platforms. B. Design and planning of UAVs flights, by the optimization of flights based on design parameters. C. Design of the methodologist for processing the information and images obtained that allows the metric sizing and modeling of the evaluated pathology. D. Development and validation of an innovative work methodology that allows to achieve the objective. According to its acronym UAVs means Unmanned Aerial Vehicle. Although the use of unmanned aircraft on a large scale is relatively recent, it is developing rapidly in a multitude of engineering fields. Thermography can be defined as a non-destructive physical methodology for measurement and visualization of surface temperatures with precision, based on the measurement of infrared radiation emitted by the bodies. The result of thermography are thermal maps or thermographic images, which represent the thermal distribution of the observed surface. Themography can be seen as a complementary tool in structural inspection activities. Photogrammetry can be defined as a technique to define the geometry and positionof objects from measurements made on photographs. The achievement of 3D models and the obtaining of quantitative information from images is supported by the general method of photogrammetric, which seeks to reproduce stereoscopic vision through 4 steps, principle that concive humans the ability to perceive the relief of things. Based on these three pillars and the support of computer tools, the first step was to analyse of sizing of flight projects using the Torrelavega University Campus as study area, for the optimization of the capture of RGB and thermal images based on a bunch of established criteria that optimize the time and volume of work. In this way, it achieve a standard recommendation for the sizing of flights carried out under the proposed work methodology. In the second phase, a procedure was developed for the integration and treatment of thermal images, analyzing the alternatives proposed by various authors and the particularities of this type of images. The proposed methodology involves working with combined or merged images, which are an interpolation between the RGB image and the thermal image of the photographed surface, processing the set of images according to the conventional workflow that is applied to RGB images for generate three- dimensional models. The metodology is materialized and contrasted with the implementation of the method in a mining plant such as the facilities of Cementos ALFA S.A. based on Mataporquera. Where the three-dimensional modeling of the entire plant was carried out, in addition, as representative structures on which to enhance the quality of the result obtained, the silo and the chimney independently were modelized too. The activities carried out consisted on two flights, a general one of the entire installation according to the established recommendations, and a second flight of enveloping perimeter detail for one of each mentioned structures, taking thermal and RGB images. From the captured photographs and by using Agisoft software, three-dimensional models were generated from the RGB images and the combined, obtaining different models depending on the georeferencing implemented in each case. The resulting models were contrasted and validated by comparing control points and measurements of distances, areas and volumes, that allows to determine the precision achieved and the deviations respect to reality. Consequently, the activities carried out in this TFM achieves the implementation of a methodology for the sizing of photogrammetric flights and the subsequent treatment that allows obtaining 3D RGB and thermal models from images obtained by sensors integrated in UAV platforms, from which qualitative thermal information and quantitative metric information can be obtained.Máster en Ingeniería de Mina

Thermal water prospection with UAV, low-cost sensors and GIS. Application to the case of La Hermida

The geothermal resource is one of the great sources of energy on the planet. The conventional prospecting of this type of energy is a slow process that requires a great amount of time and significant investments. Nowadays, geophysical techniques have experienced an important evolution due to the irruption of UAVs, which combined with infrared sensors can provide great contributions in this field. The novelty of this technology involves the lack of tested methodologies for their implementation in this type of activities. The research developed is focused on the proposal of a methodology for the exploration of hydrothermal resources in an easy, economic, and rapid way. The combination of photogrammetry techniques with visual and thermal images taken with UAVs allows the generation of temperature maps or thermal orthomosaics, which analyzed with GIS tools permit the quasi-automatic identification of zones of potential geothermal interest along rivers or lakes. The proposed methodology has been applied to a case study in La Hermida (Cantabria, Spain), where it has allowed the identification of an effluent with temperatures close to 40 °C, according to the verification measurements performed on the geothermal interest area. These results allow validation of the potential of the method, which is strongly influenced by the particular characteristics of the study areaThe authors wish to express their gratitude to the “Concepción Arenal” Grant Programme of the University of Cantabria and to the Government of Cantabria for the financial support provided for the development of the research activities (Grant Reference Number: UC-20-41)