62 documents found, page 1 of 7

Mosaic.pt flood risk framework to support management in coastal zones

Concrete block tracking in breakwater models

The protection of harbours in coastal areas, that are exposed to the action of the sea waves, is made by breakwaters. During the phase of design of new breakwaters or the rehabilitation of existing ones, the evaluation of effectiveness of the shape and of the protective elements to save the harbour, 3D scale models are built inside wave basins or wave flumes. In the testing phase, water waves are generated, and...

Points clouds and orthomosaics from photographs

The three authors of this paper work at the Applied Geodetic Division of the National Laboratory for Civil Engineering (LNEC), in Lisbon, Portugal. LNEC is a state owned research and development institution founded in 1946. It works in the various domains of civil engineering (structures, hydraulic, geotechnics, environment, materials, among others), giving it a unique multidisciplinary perspective in this fiel...

A incerteza de medição dos distanciómetros eletromagnéticos usados na observaçã...

Este relatório apresenta uma metodologia para controlo dos erros instrumentais e avaliação da incerteza de medição dos distanciómetros eletromagnéticos (DEM) usados na observação geodésica de barragens de betão. A metodologia, que é baseada numa base de teste existente no campus do LNEC, é ilustrada com a análise de seis medições da base, entre 2010 e 2014, com os dois DEM utilizados pelo Núcleo de Geodesia Apl...

Monitoring structure and regional-level displacements for Lisbon using multitem...

The city of Lisbon is the capital of Portugal and has been devastated by catastrophic events in the past, such as earthquakes and tsunamis. This study provides a regional analysis of displacements for the city and its neighbourhoods, between 2008 and 2010, through the application of mutitemporal InSAR techniques on Envisat ASAR images. Smaller areas with identified problems were subjected to a more refined proc...

Dam regional safety warning using time-series InSAR techniques

Accurate and frequent monitoring of dams and its surroundings is an extremely important task to ensure the safety of settlements located downstream. Time-series InSAR techniques are a cost-effective way for measuring millimeter-level displacements on the Earth surface, at a regional scale, and can be used as an early warning system for the safety of structures and their surroundings. This study presents the app...

Visual inspection aided by digital photography: application to the slopes of Fo...

This paper presents a methodology for aided visual inspections of rock slopes based on change detection techniques usually used in remote sensing. This methodology, that uses photographs taken by an ordinary digital camera, has undergone several field tests during the excavation works of Foz Tua dam. Its main goal is to detect displacements of the visible rock blocks that can lead to rock falls and to mitigate ...

Unmanned aerial vehicles (UAV) as a support to visual inspections of concrete dams

Drone or UAV (unmanned aerial vehicle) are the most common names used to refer light aircrafts without human pilots aboard. This paper presents one application that explores its use as a carrier of digital cameras, allowing the acquisition of images at distances of a few meters of a dam. Dams, and especially large dams, are structures that usually present high risk. For this reason they are subject to surveilla...

Point clouds and orthomosaics from photographs their use in a Civil Engineering...

Generating point clouds or orthomosaics from photographs can be a very affordable and easy way of access to valuable information of an object or a surface. Close range photographs, good acquisition geometry, allows that one can achieve high quality point clouds and othomosaics, sometimes reaching sub-millimetre accuracy. The authors of this paper, the three working in the National Laboratory for Civil Engineeri...

Monitorização de estruturas com interferometria SAR

A monitorização de estruturas é uma atividade de grande importância para garantir a segurança de pessoas e bens. A geodesia tem um papel determinante nesta tarefa ao possibilitar a medição de deslocamentos em zonas de interesse com elevada precisão. A interferometria por radar de abertura sintética (InSAR) permite obter deslocamentos numa rede de observação que contempla não só a estrutura, mas também a sua env...