http://repositorio.lnec.pt:8080/jspui/handle/123456789/44 2026-10-26T10:19:05Z 2026-10-26T10:19:05Z Lima, J. N. Roque, D. http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019874 2026-09-03T14:59:03Z 2026-05-01T00:00:00Z

GEODAM – Geodetic methods of automatic monitoring / Métodos geodésicos de monitorização automática - Relatório de progresso do projeto do P2I/LNEC 2021/2027 Lima, J. N.; Roque, D. O projeto Geodetic Methods of Automatic Monitoring (GeodAM) aborda, em Geodesia Aplicada, os problemas de planeamento, controlo da qualidade, estimação de parâmetros e predição na observação geodésica de barragens de betão e outras obras, pelos métodos convencionais (nivelamento geométrico e triangulação) e também por métodos espaciais (GNSS e InSAR), privilegiando o desenvolvimento de ferramentas que permitam a monitorização automática com recurso às estações em permanência in situ. A monitorização automática possibilita um acompanhamento das obras quase em tempo real, representando uma mais-valia para os donos de obra. Este relatório apresenta a descrição da atividade desenvolvida entre 2024 e 2025. Analisam-se e avaliam-se os resultados obtidos face aos objetivos inicialmente traçados e, por último, propõe-se a sua revisão, devido aos constrangimentos, e as perspetivas futuras.

2026-05-01T00:00:00Z Roque, D. Henriques, M. Lima, J. N. http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019865 2026-09-03T14:20:58Z 2026-04-01T00:00:00Z

DICE – Imagens digitais para apoio a estudos de Engenharia Civil - Relatório de progresso do projeto P2I/LNEC 2021/2027 Roque, D.; Henriques, M.; Lima, J. N. Este relatório apresenta a descrição da atividade desenvolvida no âmbito do projeto DICE, entre 2024 e 2025. Os resultados da atividade são analisados e avaliados, em face dos objetivos inicialmente previstos, sendo proposta a revisão do plano de atividades.

2026-04-01T00:00:00Z Diaz, A. Roque, D. Lima, J. N. Rodríguez, J. Solla, M. http://repositorio.lnec.pt:8080/jspui/handle/123456789/1019141 2026-05-04T15:34:20Z 2025-09-01T00:00:00Z

Improvement of InSAR displacements based on GNSS station calibration over corner reflector Diaz, A.; Roque, D.; Lima, J. N.; Rodríguez, J.; Solla, M. This article presents an analysis of the effectiveness of performing a calibration through Global Navigation Satellite System (GNSS) data on different approaches of the Interferometric Synthetic Aperture Radar (InSAR). InSAR has become a key technique for monitoring ground surface, but its results often exhibit systematic biases and deviations from ground truth measurements. This study addresses the need for more reliable displacement data by evaluating a GNSS-based calibration approach across three InSAR processing approaches: i) Persistent Scattering Interferometry (PSI) method using the open-source software StaMPS, ii) PSI method using the commercial SARPROZ software and iii) the Quasi-PS method implemented with SARPROZ. Sentinel-1 A/B data from both ascending and descending orbits, covering the period from October 2017 to January 2019, were used. Displacement errors from the same points were modeled using polynomial regressions and calibrated using reference data from GNSS and levelling, both with submillimeter precision. The effectiveness of the calibration was assessed at two levels: locally (via a corner reflector) and globally (via a GNSS baseline several kilometers long). Results show that 25 out of 27 displacement time series required correction in the mean value, with StaMPS showing the greatest need for calibration. The calibration improved the original results at all scales and acted mainly on the mean difference, with linear calibration being the most robust and consistent option. These findings highlight the importance of incorporating ground truth data to enhance InSAR reliability and support its application in geodetic and structural monitoring.

2025-09-01T00:00:00Z Henriques, M. J. Silva, H. http://repositorio.lnec.pt:8080/jspui/handle/123456789/1018817 2025-11-27T12:21:48Z 2025-04-01T00:00:00Z

Drone survey of an embankment dam to detect surface changes Henriques, M. J.; Silva, H. A point cloud is a set of three-dimensional coordinates, to which color (that of the object's surface) can be added. It's a simple way to reproduce this object (which could be a dam, a building, a breakwater, a street, a room) on the computer. The point cloud can be obtained by laser scanner survey, photogrammetric survey and, in the case of small objects, also by 3D scanning. The coordinates resulting from laser scanners and photogrammetric surveys are generally obtained with less accuracy than those obtained by classical methods developed within the scope of geodesy and surveying (topography). For this reason, the use of point clouds (and the 3D models created from these) in dams to detect changes, for example for safety control studies, is more suitable to embankment dams as these are works where there is a requirement for slightly lower accuracy of results, on the order of few centimetres. Despite being less precise coordination methods, the laser scanner and photogrammetric methods have a very important advantage in earthworks as they cover the entire surface with a cloud with a high density of points. A localized problem can be easily detected if it has an expression on the surface of the work. As part of a study aimed at obtaining better knowledge of some details of an embankment dam situated in Portugal, two aerial photogrammetric surveys were carried out, approximately one year apart, with a drone. From these surveys point clouds and 3D models of the dam's surface were created. The communication presents various aspects of the surveys as well as the clouds and models generated.

2025-04-01T00:00:00Z