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Publicações

Publicações por Joaquim João Sousa

2013

The viStaMPS tool for visualization and manipulation of time series interferometric results

Autores
Sousa, JJ; Magalhaes, LG; Ruiz, AM; Sousa, AMR; Cardoso, G;

Publicação
COMPUTERS & GEOSCIENCES

Abstract
In the last decade, Synthetic Aperture Radar Interferometry (InSAR) has become operational as a technique that allows remote detection of deformation at the Earth's surface. Analysis of time series of SAR images extends the area where InSAR can be successfully applied and also permits detection of smaller displacements through the reduction of error sources. Stanford Method for Persistent Scatterers (StaMPS) InSAR implementation, which is based on the processing of multi-temporal SAR data, is widely used for ground deformation monitoring. This is due mainly to its proven reliability and freeware distribution among the scientific community. However, some issues can make the interpretation of the results a difficult task: StaMPS supports data processing based on command prompt, which increases the difficulty of usage by users not familiar with the specific programming language that supports StaMPS. Moreover, several visualization tasks are not implemented in the standard approach requiring that each user develop its own code for visualization and interpretation purposes. In this paper, we present viStaMPS, a new visual application developed to enhance the visualization, manipulation and exportation of StaMPS results. The programmed application is developed in Matlab through the Graphical User Interface (GUI) and no coding is required for running it, which avoids any programming language knowledge for standard uses. The included graphical interface is very versatile allowing the user to choose among several features: visualization, manipulation and exportation of data which are not available in the original StaMPS.

2015

Monitoring of landslide activity in Slovakia territory using multi-temporal insar techniques

Autores
Bakon, M; Papco, J; Perissin, D; Lazecky, M; Sousa, JJ; Hlavacova, I; Batorova, K; Ondrejka, P; Liscak, P; Paudits, P; Real, N;

Publicação
European Space Agency, (Special Publication) ESA SP

Abstract
Slope deformations are the most important geohazards in Slovakia which annually cause an extensive economic damage of significant influence. About 22000 slope deformations have been registered so far, covering an area of almost 2600 km2. Since 2010, 639 new slope failures have been witnessed and their activation was driven mainly by the climatic anomalies such as extraordinary rainfalls. Many of these landslides currently represent a direct threat to the lives, health and property of the residents in the affected areas. The landslide Nizna Mysla is considered to be the second most catastrophic landslide in the history of Slovakia. Damages to buildings and engineering networks had not been identified in the'90s of the last century when the first problems with the slope stability appeared. Up-tonow monitoring techniques has currently been reassessed to account for the results from satellite Synthetic Aperture Radar (SAR) techniques.

2016

Application of Multi-Temporal Interferometric Synthetic Aperture Radar (MT-InSAR) technique to Land Deformation Monitoring in Warri metropolis, Delta State, Nigeria

Autores
Mahmud, MU; Yakubu, TA; Oluwafemi, O; Sousa, JJ; Miguel Ruiz Armenteros, AM; Arroyo Parras, JG; Bakon, M; Lazecky, M; Perissin, D;

Publicação
INTERNATIONAL CONFERENCE ON ENTERPRISE INFORMATION SYSTEMS/INTERNATIONAL CONFERENCE ON PROJECT MANAGEMENT/INTERNATIONAL CONFERENCE ON HEALTH AND SOCIAL CARE INFORMATION SYSTEMS AND TECHNOLOGIES, CENTERIS/PROJMAN / HCIST 2016

Abstract
Warri is one of the mega cities in Delta State in the coastal region of Nigeria hosting many industries. One of the three of Nigeria oil refineries is located in Warn. This study reveals the occurence of land deformation in the Warri area which is not only because it was formed in a tectonic setting but because of the high demand of the underground water for indutrial and domestics uses, high population density and oil and gas exploration in the area. Land deformation in this area is currently being accelerated by this indiscriminate withdrawal of underground water from the aquifers and exploration of the oil and gas leading to the compacting sediments. In this study Multi-Temporal Interferometric Synthetic Aperture Radar (MT-InSAR) technique was applied to monitor land deformation in Warri metropolis in the period between 09/02/2006 and 12/08/2010 with Envisat data obtained from European Space Agency (ESA). The processing was done using Stanford Method for Persistent Scatterers/Multi-Temporal InSAR (StaMPS). From the analysis of the results, land deformation is occurring in Warri metropolis at a moderate rates (+/-5 mm/yr). During the preliminary investigations, structures, particularly buildings, were physically observed subsiding while some others with cracks of various types and degrees. (C) 2016 The Authors. Published by Elsevier B.V.

2017

Bringing together UAS-based land surveying and procedural modelling of buildings to set up enhanced VR environments for cultural heritage

Autores
Adao, T; Padua, L; Hruska, J; Peres, E; Sousa, JJ; Morais, R; Magalhaes, LG;

Publicação
2017 24 ENCONTRO PORTUGUES DE COMPUTACAO GRAFICA E INTERACAO (EPCGI)

Abstract
A methodology to rapidly produce environments that combine the intuition of in situ augmented reality (AR) with the commodity of virtual reality (VR) is proposed in this paper, by bringing together unmanned aerial systems (UAS) imagery and procedural modelling. While fully synthesized environments provide a very accurate visualization of the conserved parts of the real-world, missing parts - namely ruins - can be complemented with procedurally modelled structures. Regarding methodology's steps, firstly, a UAS flight mission gathers georeferenced imagery data about the site of interest. Then, the image set is converted to an accurate 3D model of the referred site, through photogrammetry. By considering the geographic information that also results from the previous process, ruins are manually outlined for georeferencing purposes. To complement ruins' missing information, virtual models of buildings are produced too, in a procedural modelling tool. Finally, at the full VR environment setup step, all elements are imported and subjected to geometric transformations that aim to match the procedurally modelled buildings with the outlined ruins. To improve the insight about the process work-flow, system's architecture and implementation are presented along with a case-study regarding a historically relevant site - Vila Velha's city gates (Vila Real, Portugal) - and preliminary results.

2016

Multi-sensor InSAR deformation monitoring over urban area of Bratislava (Slovakia)

Autores
Bakon, M; Papco, J; Perissin, D; Sousa, JJ; Lazecky, M;

Publicação
INTERNATIONAL CONFERENCE ON ENTERPRISE INFORMATION SYSTEMS/INTERNATIONAL CONFERENCE ON PROJECT MANAGEMENT/INTERNATIONAL CONFERENCE ON HEALTH AND SOCIAL CARE INFORMATION SYSTEMS AND TECHNOLOGIES, CENTERIS/PROJMAN / HCIST 2016

Abstract
The integrated use of multiple Synthetic Aperture Radar (SAR) platforms for the deformation monitoring via satellite radar interferometry offers several perspectives for investigation of the behaviour of new and ageing structures, such as buildings and infrastructures, under varying or hazardous environment. Spanning almost 24 years of space-borne radar observations, this study aims to perform classical PSInSAR (Persistent Scatterer Interferometric Synthetic Aperture Radar) analysis incorporating measurements of ERS, Envisat, TerraSAR-X, Sentinel-1A and Radarsat-2 satellites. The results from the processing of different sensing geometries over Bratislava (Slovakia) urban area are presented, focusing on the description of characteristics associated with the specifics of every satellite platform in use. The discussion over technical feasibility of infrastructure monitoring is accompanied by the outline of possible future needs for the utilisation of the wealth source of information provided by the satellite radar imagery. (C) 2016 The Authors. Published by Elsevier B.V.

2016

POTENTIAL OF SENTINEL-1A FOR NATION-WIDE ROUTINE UPDATES OF ACTIVE LANDSLIDE MAPS

Autores
Lazecky, M; Comut, FC; Nikolaeva, E; Bakon, M; Papco, J; Ruiz Armenteros, AM; Qin, Y; de Sousa, JJM; Ondrejka, P;

Publicação
XXIII ISPRS CONGRESS, COMMISSION VII

Abstract
Slope deformation is one of the typical geohazards that causes an extensive economic damage in mountainous regions. As such, they are usually intensively monitored by means of modern expertise commonly by national geological or emergency services. Resulting landslide susceptibility maps, or landslide inventories, offer an overview of areas affected by previously activated landslides as well as slopes known to be unstable currently. Current slope instabilities easily transform into a landslide after various triggering factors, such as an intensive rainfall or a melting snow cover. In these inventories, the majority of the existing landslide-affected slopes are marked as either stable or active, after a continuous investigative work of the experts in geology. In this paper we demonstrate the applicability of Sentinel-1A satellite SAR interferometry (InSAR) to assist by identifying slope movement activity and use the information to update national landslide inventories. This can be done reliably in cases of semi-arid regions or low vegetated slopes. We perform several analyses based on multitemporal InSAR techniques of Sentinel-1A data over selected areas prone to landslides.

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