Material multimedia per l'aprenentatge autònom a l'àmbit geomàtic

Peer Reviewe

Automatic manhole extraction from MMS data to update basemaps

Basemaps are the main resource used in urban planning, building and infrastructure asset management. Therefore, they must be accurate and up to date to better serve citizens, contractors, property owners and town planning departments. Traditionally, they have been updated by aerial photogrammetry, but this is not always possible and alternatives need to be sought. In such cases, a useful option for large scales is the mobile mapping system (MMS). However, automatic extraction from MMS point clouds is limited by the complexity of the urban environment. Therefore, the influence of the urban pattern is analysed in three zones with varied urban characteristics: areas with high buildings, open areas, and areas with a low level of urbanization. In these areas, the capture and automatic extraction of 3D urban elements is performed using commercial software, which is useful for some elements but not for manholes. The objective of this study is to establish a methodology for extracting manholes automatically and completing hidden buildings' corners, in order to update urban basemaps. Shape and intensity are the main detection parameters for manholes, whereas additional information from satellite image Quickbird is used to complete the buildings. The worst rate of detection for all the extracted urban elements was found in areas of high buildings. Finally, the article analyses the computing cost for manhole extraction, and the economic cost and time consume of the entire process, including the proposed methodolgy using an MMS point cloud and the traditional survey in this case.Peer ReviewedPostprint (updated version

Spatial data infrastructure (SDI) for inventory rockfalls with fragmentation information

The version of record of this article, first published in Natural Hazards is available online at Publisher's webside: https://doi.org/10.1007/s11069-022-05282-2The fragmentation phenomenon has a significant effect on rockfall risk assessment. This information is difficult to obtain, but it is key to improving rockfall modelling. For this reason, the RockModels team has gathered data on the fragmentation of several natural events since 2014 that nowadays wants to share them with professionals, academics and stakeholders. The best way for the dissemination of this information is the use of standard or data specifications in order to be interoperable. A fragmentation rockfall database has been created using all the gathered information, according to the INSPIRE Natural Hazard Area Data Specification currently in force. However, new tables have had to be added, since this specification does not consider fragmentation data. There are currently 6000 records of geometries of source areas, envelopes, deposits and mostly individual blocks. A web mapping application, with an automatic function for coordinate reference system transformation, has been created to facilitate access to the spatial database information. All that was developed on open-source software such as OpenLayers JavaScript library, database (PostGre-PostGIS) and the map generating Web Map Service (GeoServer). As more data are collected, the database can be easily updated and the new information will be published. Moreover, to improve data interpretation, a future task is to incorporate 3D models on the web application. The existence of this public database will facilitate research and advance in knowledge of this kind of natural hazards.Peer ReviewedPostprint (published version

Necesidad del geoide en el posicionamiento con GPS

The common use of global positioning systems, and specially GPS, in work like survey, cartography, photogrammmetry, LIDAR... make it necessary have a gemid model to transform ellipsoidal to orthometric heights used in engineering. Because of the lack of parallelism between both reference systems not to have these models can produce important errors since the variation can take values of 10cm/Km or more in some areas, for example in the SW of Spain. If we do not consider this difference in the elaboration of DTM used to design substructure can happen that in gravity canalization the water does not arrive at the wanted poin

Integración de MDT's para intervenciones urbanísticas

Desde la implantación de los núcleos habitables primitivos hasta hoy en día se han desarrollado diferentes métodos para poder llevar a cabo el estudio y análisis del territorio. Todos estos estudios han tenido últimamente un aliado imprescindible en los sistemas de representación, e información del territorio a partir de las aplicaciones de sistemas informáticos que han permitido los avances en las tecnologías de la comunicación. Las aportaciones que se han hecho a nivel de usuario genérico, a partir de Google Earth y similares han hecho posible que sea fácilmente accesible la visualización de entornos urbanos y rurales. Las facilidades de acceso a diferentes institutos ligados a las administraciones Territoriales, Autonómicas y del Estado ponen al alcance datos técnicos que permiten adaptarlos a las necesidades de diferentes profesionales en sus labores de planificación y análisis del terreno. Son estas necesidades las que nos han planteado el trabajo que estamos realizando en la formación de los futuros profesionales del planeamiento urbanístico y de la ingeniería en geomática y topografía. En la docencia de Grado y de Máster se debe trabajar con la tecnología e información disponible actualmente para alcanzar una formación cualificada en el campo de la representación y el diseño de espacios urbanos.Peer Reviewe

The use of geomatic techniques to improve the management of metro infrastructure

The management of large infrastructures requires comprehensive knowledge of their characteristics and the elements that constitute them. It is essential to know which elements are involved and where they are located. At the same time also, it is vital to understand the overall geometry. However, it is difficult to obtain this information about underground infrastructures due to their lighting characteristics, hazards, lack of GNSS (Global Navigation Satellite System) signals and time available. In this case, to achieve the required quality in both tasks, the mobile mapping systems that are widely used in large surveys and urban inventories have to be adapted to obtain data in underground conditions. To achieve this, geodesic support is necessary. Therefore, a laser scanning and kinematic photogrammetry survey was carried out to obtain the centimetric precision and complete information that is still used today. This paper presents an adaptation of these systems for use in the Ferrocarril Metropolità de Barcelona.Peer ReviewedPostprint (author's final draft

Habilidades informacionales integradas en los grados de edificación y geomática (EPSEB-UPC): caso práctico de cooperación entre docentes y bibliotecarios

Se expone el caso práctico de la colaboración entre PDI y PAS de biblioteca para la impartición del itinerario competencial en Habilidades Informacionales en los grados de la Escola Politècnica Superior d'Edificació de Barcelona (EPSEB). Docentes y bibliotecarios diseñan conjuntamente actividades que contemplan sesiones taller especializadas, cursos “ad-hoc” y cursos de contenidos transversales de complejidad progresiva integrados en asignaturas obligatorias. Los contenidos se adaptan a cada asignatura implicada en el itinerario y se da una orientación práctica para captar el interés de los alumnos. Coordinados por el Servei General de Biblioteques de la UPC, los bibliotecarios desarrollan material didáctico de apoyo y valoran los resultados conjuntamente de forma periódica para proponer mejoras. Las actividades se imparten en modalidad presencial y semipresencial. Así mismo, la biblioteca imparte formación al profesorado conducente tanto a desarrollar su faceta investigadora como a dinamizar la docencia en el aula. La experiencia en sesiones formativas desde el año 2000 y la buena acogida por parte de del profesorado y el estudiantado, avalan la puesta en marcha del itinerario a partir de septiembre 2009.Postprint (author's final draft

Comparison of photogrammetric techniques for rockfalls monitoring

The use of Unmanned Aerial Vehicles, UAVs to image capture for monitoring natural hazards has had a major boost for its wide possibilities in the last decade. These are, for example, the studying and monitoring of unstable slopes, glaciers and rocky escarpments. Moreover, to evaluate the risk after a rockfall or debris flow event, for example measuring volume of displaced material, trajectories of blocks or building and/or infrastructure damaged. But the use of these devices requires a specific treatment regarding the studied case and geomatic techniques suitable to get the adequate precision of the movement, size of items or events to study. For each application it is necessary to determine what kind of capture is the most appropriate to obtain an optimal benefit-cost ratio. A comparison of the use of terrestrial photogrammetry, UAV photogrammetry and video from UAV has been done. The best result has been obtained combining techniques aerial and terrestrial since ground points with a best quality can be identified and measured and all the surface has a best image coverage.Peer ReviewedPostprint (published version

Metric survey of the monument of Queen Elisenda's Tomb in the monastery of Pedralbes, Barcelona

When an urban development is planned the cartography of this territory is necessary, in the same way before starting a project to rehabilitate a monument the graphic information about it has to be available. At present, different techniques are available which allow to obtain three-dimensional models with a different accuracy level and runtimes. This paper shows the work carried out to obtain the graphic information and three-dimensional models that are necessary for the rehabilitation project of the tomb of Queen Elisenda in the Monastery of Pedralbes, Barcelona (Spain). This monument has the peculiarity of being symmetrical about the wall separating monastery church and the cloister. To do this, different techniques have been used that allow us to obtain an accurate model and as complete as possible, for the analysis of the construction process of the monument. In order to achieve the complete architectural survey the integration of laser scanning and photogrammetric data, and CAD models has been necessary. Due to the detail of the sculptures and the Queen’s sarcophagus two sensors, with different resolution, range and accuracy, have been used to obtain the laser scanning data. Stereo pairs have been taken to obtain the 3D model of these elements to complete the model and obtain an ortophotography. In this way, a comparative analysis of both techniques has been carried out, in order to decide which one is the suitable for certain application. This investigation has been restricted to the tomb, in the two symmetrical parts of the monument.Peer ReviewedPostprint (published version

Fotogrametría y videogrametría desde UAV para la captura de geoinformación en estudios geológicos

tripulados (UAV en sus siglas en inglés) ha tenido un gran impulso en la última década por sus amplias posibilidades. Entre otros riesgos naturales, los deslizamientos de ladera rápidos y la caída de bloques rocosos tienen un gran potencial de causar daños, tanto humanos como materiales. Este tipo de movimientos ocurren en zonas de gran pendiente (> 45°), muy poco accesibles en la práctica, lo que suele impedir la obtención sobre el terreno de una serie de datos completa y representativa y, por otra parte, entraña un riesgo para los observadores. El uso de UAV como plataforma para sensores de captura de información geoespacial en estudios geológicos está plenamente justificada en estos casos en que no es recomendable la proximidad a la zona activa. En el uso de estos dispositivos no se pueden utilizar siempre los mismos parámetros, sino que requiere de un tratamiento específico para cada caso de estudio. Su elección depende de la precisión requerida, así como, del tipo y del tamaño de movimiento de la ladera. En la actualidad existen gran variedad de vehículos aéreos no tripulados y cámaras fotográficas que permiten la toma de vídeo y fotografía fija, así como otros tipos de sensores (cámaras de infrarrojo cercano, termografía, LiDAR…). Para cada aplicación, es necesario determinar qué tipo de captura es el más adecuado para obtener una óptima relación coste-beneficio. En esta ponencia nos centramos en la captura de imágenes desde multicópteros considerando dos fuentes diferentes de información: fotografía y vídeo. Se analizarán las características y precisiones de los modelos obtenidos con ambos tipos de captura y con la captura con fotogrametría terrestre, así como las posibles aplicaciones de la información en función de la calidad obtenida. El área de prueba ha sido uno de los frentes de una cantera ubicada en la región de “El Garraf”, al SO de la provincia de Barcelona. La pared de la cantera es de roca caliza, de aproximadamente 100 m de longitud y 75 m de alto, y en la actualidad presenta varias cicatrices y grietas con interés geológico. Además en esta pared se produjo un desprendimiento de rocas hace pocos meses que dañó alguno de los almacenes situados más abajo, en las cercanías. Se han obtenido modelos independientes utilizando cada tipo de captura: UAV y terrestre, y combinando ambos, tanto en el caso de vídeo como fotografía. Los resultados obtenidos muestran la ventaja del empleo de las imágenes terrestres para la georreferenciación y ajuste del bloque fotogramétrico conjunto.Peer ReviewedPostprint (published version