Guimarães, Portugal
No Thumbnail Available
Volume
Number
Issue Date
Journal Title
Journal ISSN
Journal Volume
Articles
QGIS approach to extract fluvial terraces for archaeological purposes using remote sensing data
Duarte, Lia; Gomes, Alberto; Teodoro, Ana Cláudia; Monteiro-Rodrigues, Sérgio
Fluvial terraces, normally defining flattened surfaces are significant geomorphic features that explains the presence of rivers at high altitudes and constitute the remains of the old river along the valley. In Iberia, many of these terraces preserve Paleolithic artifacts and document the presence of the first human communities. Nowadays, the increasing use of Free and Open Source Software (FOSS) provides the opportunity to analyze and test different approaches to study these geomorphological features. According to the literature, several algorithms from open source GIS software have been used, such as Geographic Resources Analysis Support System (GRASS) GIS. In the recent versions, QGIS, a GIS open source software, is integrated with several algorithms from other software, such as GRASS GIS, System for Automated Geoscientific Analyses (SAGA), Orfeo-ToolBox (OTB), among others. Therefore, the procedures used to extract and identify fluvial terraces can be performed using QGIS software. The objective of this work was to combine Remote Sensing data and GIS algorithms in QGIS to identify fluvial terraces in order to support archaeological prospection of Paleolithic artifacts along the Minho River (Portugal border). Different data were used such as Digital Surface Model (DSM), slope derived from DSM, Normalized Difference Vegetation Index (NDVI) map derived from Sentinel 2A images (summer), Land Use Land Cover (LULC) derived from Corine Land Cover (CLC) and hydrological data from Minho valley. The method proposed allowed the definition of a fluvial staircase considering several terraces levels along the Minho valley. The data used were in WGS84 UTM zone 29 (EPSG:32629) and the spatial resolution adopted was 10 meters. Different scenarios were tested and the results were validated considering in situ measurements, in order to find the best weight associated to each parameter.
Robust Railroad Cable Detection in Rural Areas from MLS Point Clouds
Cserép, Máté; Hudoba, Péter; Vincellér, Zoltán
Monitoring of the railroad infrastructure is crucial for safety concerns and accident prevention. This task requires regular surveillance which is nowadays still carried out by expensive and time consuming manual visual inspections in many countries. The problem of railroad cable recognition (contact cables, catenary cables, return current cables) in rural areas based on LiDAR point clouds has it own methods, but current state of the art solutions suffer from extremely high computational load due the extensive size of the datasets. In this study we analyzed and compared novel robust solutions focusing on minimizing the assumptions (positions and distances of track bed, rail tracks, etc.) of the algorithms, and providing faster filtering methods that prepare the point cloud by removing the most of the points that cannot be part of a cable. Beside implementing the investigated methods based on open source libraries, we created a framework for algorithm pipelining, input, output and intermediate result management, and performance analysis.
Grassland Recognition with the Usage of Thermal Weights
Mangafić, Alen; Mesner, Nika; Triglav Čekada, Mihaela
In this paper we apply the usage of thermal weights, a new variable for geostatistical analysis and we present the method for their determination. In the case study we tested a data fusion between Sentinel-2 and Landsat 7/8 data, to incorporate also the thermal factor in the detection of land cover changes. The process distinguishes grasslands from other crops with similar vegetative appearance and offers us the possibility to create a new statistical sample with just grasslands. The data fusion is incorporated in the calculation of Land Surface Temperature (LSTFU) by combining the Sentinel-2 derived Normalized Difference Vegetation Index (NDVI), and from it derived land surface emissivity, with the Landsat 7/8 derived Top of Atmosphere Brightness Temperature (TOABT). The experimental LSTFU is modified into a normalized assessment variable by a time-series analysis. The result is a thermal weight layer which can help us in further object-based image analyses and classification. The thermal weight is calculated from Sentinel-2 and Landsat 7/8 datasets that has small acquisition time gaps between them. The accuracy assessment due to time gaps and sensor differences was evaluated with Cohens’s kappa (κ) and correlation matrix validation. The data fusion is made to test if a Sentinel-2 fusion approach could improve the Thermal Weight created just by Landsat imagery. The purpose was to evaluate the importance of thermal bands for LU/LC cover.
Hydraulic modeling for the assessment of flood hazard using the Iber software in the Amarante urban center
Martins, Márcia; Gomes, Alberto; Pinto Santos, Pedro
Recently, there is an availability increase of hydraulic modeling software that allows the analysis and definition of several hydraulic variables, namely water depth and flow velocity, which are important parameters for the assessment and management of flood-prone areas. The growing use of this software is related with the fact of being Free and Open Source Software (FOSS), making possible the understanding of different approaches and providing most reliable and accurate results of flood-prone areas according different return periods. In this study it was used the freely hydraulic software Iber, a tool for two-dimensional modeling of water flow in rivers and estuaries that provides the hydraulic variables (water depth and velocity) required for the definition of flooded areas. The main objective of this work was the analysis of flood hazard at the city of Amarante (North of Portugal), a place frequently affected by these extreme events. Due to the huge concentration of activities and services along the flood-prone area, economic and social damages caused by floods in the historical and urban center of Amarante are very important. Therefore, hydraulic modeling of the flooded area was performed for different return periods (10, 100 and 500 years) using the Iber software. The main results shows the maximum extent of the flood, the water depth and the flow velocity for a specific return period and also, a flood hazard map for the return period of 100 years. This case study aims to contribute for a better management of flood risk, which is a challenge for competent authorities, namely the local civil protection, fireman's and municipality services.
istSOS Version 3
Massimiliano, Cannata; Antonovic, Milan; Strigaro, Daniele; Cardoso, Mirko
istSOS version 3 is a new full stack open source application framework that, implementing the Sensor Observation Service standard from the OGC and including some special features, offers the capability to manage and disseminate observation from sensors networks. istSOS3 has been redesigned with the mission to solve the problems of high loads environments and quality of service. After some recent researches that have shown that istSOS version 2 is not adequate to meet high demanding environment in terms of high concurrency, big data and performance, istSOS version 3 has been rewritten from ground up taking advantages from the latest technologies and approaches like Python3 asynchronous programming, real time caching, ReactJS and JavaScript Compilers. istSOS3 server includes a Web based administration interface that permits an easy access to configurations and management operations, making the usage of OGC-SOS more user-friendly. But istSOS3 is also a developer friendly framework. All the components has been separated and can be reused creatively to meet different needs. New plugins can be easily integrated into the istSOS Python module or included in the web interface or create new ones.