11 documents found, page 1 of 2
The large trans-Neptunian object 2002 TC302from combined stellar occultation, p...
Ortiz, J. L.; Santos-Sanz, P.; Sicardy, B.; Benedetti-Rossi, G.; Duffard, R.; Morales, N.; Braga-Ribas, F.; Fernández-Valenzuela, E.; Nascimbeni, V.Made available in DSpace on 2020-12-12T01:33:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-07-01; Context. Deriving physical properties of trans-Neptunian objects is important for the understanding of our Solar System. This requires observational efforts and the development of techniques suitable for these studies. Aims. Our aim is to characterize the large trans-Neptunian object (TNO) 2002 TC302. M...
Inspeção visual assistida de paramentos de barragens de betão
Ramos, S.; Roque, D.; Fonseca, A. M.; Navarro, A.A comunicação apresenta um estudo de aplicação de técnicas de Processamento Digital de Imagens (PDI) à inspeção visual de obras de engenharia, neste caso particular, o paramento da barragem do Covão do Meio na Serra da Estrela. A Inspeção Visual Assistida consiste no levantamento fotográfico e na monitorização da evolução de patologias através da aplicação de algoritmos de Processamento Digital de Imagem. O est...
Introducing mapping standards in the quality assessment of buildings extracted ...
Freire, S.; Santos, T.; Navarro, A.; Soares, F.; Silva, J.D.; Afonso, N.; Fonseca, A.; Tenedório, J.Many municipal activities require updated large-scale maps that include both topographic and thematic information. For this purpose, the efficient use of very high spatial resolution (VHR) satellite imagery suggests the development of approaches that enable a timely discrimination, counting and delineation of urban elements according to legal technical specifications and quality standards. Therefore, the nature...
Avaliação Preliminar da Qualidade Posicional de uma Orto-Imagem QuickBird
Afonso, N.; Fonseca, A. M.; Lima, J. N.; Santos, T.; Freire, S.; Navarro, A.; Tenedório, J.Este trabalho foi realizado no âmbito do projecto GeoSAT, que teve como objectivo a definição de metodologias para extracção de informação geográfica a partir de imagens de satélite de alta resolução em ambiente urbano. Nesta comunicação apresentam-se e descrevem-se os processos de avaliação da qualidade posicional, de uma orto-imagem do satélite QuickBird da cidade de Lisboa, desde a recolha dos pontos até à a...
Preliminary Assessment of the Positional Accuracy of a Quickbird Ortho Image
Afonso, N.; Fonseca, A. M.; Lima, J. N.; Santos, T.; Navarro, A.; Tenedório, J.This work has been accomplished on the scope of the GeoSAT research project, where the main goal was the definition of methodologies for geographic information extraction from high-resolution satellite images in an urban environment. This paper is intended to present and describe the positional quality assessment processes, of a QuickBird satellite ortho image from the city of Lisbon. For evaluate the possible ...
Hierarchical object-based classification of dense urban areas by integrating hi...
Dinis, J.; Navarro, A.; Soares, F.; Santos, T.; Freire, S.; Fonseca, A.; Afonso, N.; Tenedório, J.In Portugal, updating municipal plans (1:10 000) is required every ten years. High spatial resolution imagery has shown its potential for detailed urban land cover mapping at large scales. However, shadows are a major problem in those images and especially in the case of urban environments. The purpose of this study is to develop a less time consuming and less expensive alternative approach to the traditional g...
Hierarchical object-based classification of dense urban areas by integrating hi...
Dinis, J.; Navarro, A.; Soares, F.; Santos, T.; Freire, S.; Fonseca, A. M.; Afonso, N.; Tenedório, J.In Portugal, updating municipal plans (1:10 000) is required every ten years. High spatial resolution imagery has shown its potential for detailed urban land cover mapping at large scales. However, shadows are a major problem in those images and especially in the case of urban environments. The purpose of this study is to develop a less time consuming and less expensive alternative approach to the traditional g...
Extracting buildings in the city of Lisbon using Quickbird images and lidar data
Santos, T.; Freire, S.; Navarro, A.; Soares, F.; Dinis, J.; Adriano, P.; Fonseca, A. M.; Tenedório, J.The methodology is based on semi-automatic extraction of features, using information from a QuickBird image and LIDAR data. The QuickBird image is suitable to delineate the different elements on the surface based on their spectral characteristics. However, this task is much more successful and richer when altimetric information is also used in the extraction process. Thus, with the introduction of LIDAR data, w...
Cartographic data extraction from airborne imagery by hierarchical-based morpho...
Soares, F.; Navarro, A.; Santos, T.; Freire, S.; Fonseca, A. M.; Afonso, N.; Tenedório, J.This paper presents a comprehensive approach to effectively extract cartographic urban data from high resolution satellite imagery. It consists of a sequence of image processing techniques, for image segmentation, based on RGB band separation, analysis and preprocessing, followed by a morphological-based approach for data segmentation. The chosen image objects for this study are roof-tile buildings and road net...
Muller’s ratchet and the pattern of variation at a neutral locus
Gordo, I.; Navarro, A.; Charlesworth, B.The levels and patterns of variation at a neutral locus are analyzed in a haploid asexual population Undergoing accumulation of deleterious mutations due to Muller's ratchet. We find that the movement Of Muller's ratchet can be associated with a considerable reduction in genetic diversity below classical neutral expectation. The extent to which variability is reduced is a function Of the deleterious initiation ...