14 documents found, page 1 of 2
The FireLoc Project: Identification, Positioning and Monitoring Forest Fires wi...
Fonte, Cidália C.; Cardoso, Alberto; Estima, Jacinto; Almeida, J.-P. de; Patriarca, JoaquimThe severity and impacts of forest fires have increased in the last years in several parts of the world, where devastating fires occur now almost every year. As these types of events are likely to increase due to climate changes, it is important to develop tools to assist authorities in the early identification and geolocation of ignitions so that they can be tackled as fast as possible. Several types of system...
Automatic Extraction and Filtering of OpenStreetMap Data to Generate Training D...
Fonte, Cidália C.; Patriarca, Joaquim; Jesus, Ismael; Duarte, DiogoThis paper tests an automated methodology for generating training data from OpenStreetMap (OSM) to classify Sentinel-2 imagery into Land Use/Land Cover (LULC) classes. Di erent sets of training data were generated and used as inputs for the image classification. Firstly, OSM data was converted into LULC maps using the OSM2LULC_4T software package. The Random Forest classifier was then trained to classify a time...
Analysing the Potential of OpenStreetMap Data to Improve the Accuracy of SRTM 3...
Monteiro, Elisabete S. V.; Fonte, Cidália C.; Lima, João L. M. P. deTerrain slope and drainage networks are useful components to the basins morphometric characterization as well as to hydrologic modelling. One way to obtain the slope, drainage networks, and basins delineation is by their extraction from Digital Elevation Models (DEMs) and, therefore, their accuracy depends on the accuracy of the used DEM. Regional DEMs with high detail and accuracy are produced in many countrie...
Improving the positional accuracy of drainage networks extracted from Global Di...
Monteiro, Elisabete S. V.; Fonte, Cidália C.; Lima, João L. M. P. deDrainage networks allow the extraction of topographic parameters that are useful for basins characterization and necessary for hydrologic modelling. One way to obtain drainage networks is by their extraction from Digital Elevation Models (DEMs). However, it is common that no freely available DEMs at regional or national level exist. One way to overcome this situation is to use the available free Global Digital ...
On the Contribution of Volunteered Geographic Information to Land Monitoring Ef...
Arsanjani, Jamal Jokar; Fonte, Cidália C.Land-related inventories are important sources of geoinformation for environmentalists, researchers, policy-makers, practitioners, and ecologists. Traditionally, a considerable amount of energy, time, and money have been dedicated to map global/regional/local land use datasets. While remote sensing images and techniques along with field surveying have been the main sources of data for determining land use featu...
Assessing positional accuracy of drainage networks extracted from ASTER, SRTM a...
Monteiro, Elisabete; Fonte, Cidália C.; Lima, João L.M.P.This study intends to evaluate the positional accuracy and compare the completeness of the drainage networks extracted from three sources of free geographic data, namely from the Digital Elevation Models ASTER and SRTM and the collaborative project OpenStreetMap (OSM), in an area included in the basin of Mondego river, located in the centre of continental Portugal. The drainage networks extracted from ASTER and...
A Hybrid approach for land cover mapping based on the combination of soft class...
Luisa M. S. Gonçalves; Fonte, Cidália C.In this article, the authors present a hybrid approach to produce more accurate land cover maps of diverse landscapes representing Mediterranean environments. The innovation of the proposed methodology is to use, in the combination of soft classifiers outputs, information about the classification uncertainty associated with each pixel and its neighbourhood. The hybrid combined classification method developed in...
Assessing the influence of uncertainty in land cover mapping and digital elevat...
Gonçalves, Luísa M.S.; Fonte, Cidália C.; Gomes, RicardoThis paper proposes an approach to assess the influence of the uncertainty present in the parameters dependent on the land cover and elevation data over the peak flow values and the subsequent delineation of flooded areas. The proposed approach was applied to produce vulnerability and risk maps that integrate uncertainty for the urban area of Leiria, Portugal. A SPOT-4 satellite image and DEMs of the region wer...
The application of uncertainty measures in the training and evaluation of super...
Gonçalves, Luísa M. S.; Fonte, Cidália C.; Júlio, Eduardo N. B. S.; Caetano, MarioThe production of thematic maps from remotely sensed images requires the application of classification methods. A great variety of classifiers are available, producing frequently considerably different results. Therefore, the automatic extraction of thematic information requires the choice of the most appropriate classifier for each application. One of the main objectives of the research described in this artic...
Using Uncertainty Information to Combine Soft Classifications
Gonçalves, Luisa M. S.; Fonte, Cidália C.; Caetano, MarioThe classification of remote sensing images performed with different classifiers usually produces different results. The aim of this paper is to investigate whether the outputs of different soft classifications may be combined to increase the classification accuracy, using the uncertainty information to choose the best class to assign to each pixel. If there is disagreement between the outputs obtained with the...