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91.
Cledja Rolim Alejandro C. Frery Eliana Almeida Evandro Costa Luiz Marcos Gonçalves 《The Visual computer》2007,23(6):409-418
In this work we propose a new approach for fast visualization and exploration of virtual worlds based on the use of cartographic
concepts and techniques. Versions of cartographic maps with different levels of details can be created by using a set of operations
named cartographic generalization. Cartographic generalization employs twelve operators and domain-specific knowledge, being the contribution of this work their
transposition to 3D virtual worlds. The architecture of a system for 3D generalization is proposed and the system is implemented.
Differently from traditional cartographic processes, we use artificial intelligence for both selecting the key objects and
applying the operators. As a case study, we present the simplification of the historical quarter of Recife (Brazil). 相似文献
92.
Luisa M. S. Gonçalves Cidália C. Fonte Eduardo N. B. S. Júlio Mario Caetano 《International journal of remote sensing》2013,34(9):2851-2867
The 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 article is to evaluate the performance of supervised classifiers using the information provided by the application of uncertainty measures to the testing sets, instead of statistical accuracy indices. The second main objective is to show that the information provided by the uncertainty measures for the training set may be used to assess and redefine the sample sites included in this set, in order to improve the classification results. To achieve the proposed objectives, two supervised classifiers, one probabilistic and another fuzzy, were applied to a very high spatial resolution (VHSR) image. The results show that similar conclusions on the classifiers’ performance are obtained with the uncertainty measures and the traditional accuracy indices obtained from error matrices. It is also shown that the redefinition of the training set based on the information provided by the uncertainty measures may generate more accurate outputs. 相似文献
93.
H. Gonçalves J. A. Gonçalves L. Corte-Real A. C. Teodoro 《International journal of remote sensing》2013,34(24):7936-7968
Automatic image registration is a process related to several application fields: remote sensing, medicine and computer vision, among others. Particularly in the field of remote sensing, the ever-increasing number of available satellite images requires automatic image registration methods, capable of correctly aligning a new image. An automatic image registration method – CHAIR (correlation- and Hough transform-based method of automatic image registration) – is proposed, the key concept of which relies on the ‘correlation image’ produced in both the horizontal and vertical directions. In particular, the computation of the distance of an identified diagonal brighter strip in the correlation image (through the Hough transform) to an offset (the main diagonal) allows for the determination of translational shifts and consequently control points. The set of obtained control points allows for the correction of several types of distortions. The geometric correction quality achieved by CHAIR was objectively evaluated through measures recently proposed, which allow for a more complete assessment of the obtained results. The CHAIR performance was evaluated on both synthetic and real data, with different spatial resolutions and spectral contents. CHAIR has been shown to be able to correctly align two images with a subpixel accuracy, having a priori a ‘gold standard’ image covering a considerable part of the image to be registered, and has also been shown to work for images of different sensors and/or different spectral bands, situations where traditional correlation methods often yield low and smooth peaks on the correlation surface. It is also able to account for elevation differences and to some extent for rotation and scale effects. Furthermore, it has been shown to have potential for registering synthetic aperture radar (SAR) with optical images. 相似文献
94.
Gon?alo Furtado 《Nexus Network Journal》2012,14(1):3-15
Similarities can certainly be found between systems research and computational sciences, and architecture and design. The
first pair deals with information, complex dynamics and organizations; the second pair is often understood as synthetic and
systemic. Postwar history recalls a sequence of exchanges between these fields; the aim of this paper is to highlight the
relevance of some exchanges and their contemporary legacy. In this connection, the first part briefly outlines the meaning
and history of the former disciplines, highlighting the strict circular models and how first-order cybernetics evolved towards
a second order. The second part points to some exchanges between systems research, computational sciences and art forms, as
well as to its architectural legacy. To a large extent, the current architectural interest in new sciences of emergence and
complexity is rooted in the early systems research approach. Both areas are possible root sources of a future, effective built
environment. 相似文献
95.
User testing a hypermedia tour guide 总被引:4,自引:0,他引:4
Although handheld guides have been proposed as a way to enhance visitors' experience of museums and exhibitions, the authors describe user studies that actually test the theory in a real-world setting. 相似文献
96.
Hugo M. Santos Bruno Pedras Abel Tamayo Jaume Casabó Lluis Escriche Berta Covelo José Luis Capelo Carlos Lodeiro 《Inorganic chemistry communications》2009,12(11):1128-1134
Two new emissive chemosensors based on coumarin-343 have been synthesized, and their photophysical studies conducted. L1 contains an aza-thio macrocycle ring as the chelating unit, which has great affinity for soft metal ions, whereas L2 is a parent species without macrocyclic unit. Both compounds were separated by column chromatography and characterized by elemental analysis, 1H,13C NMR, UV–vis and FAB mass spectroscopy. The X-ray structures of L1 and L2 and the supramolecular interactions in the solid state are discussed. Preliminary results on the metal–ion sensing effects of the ligands are presented. Titrations with Ag+, Pd2+ and Ni2+ have been studied by UV–vis absorption and fluorescence spectroscopy. 相似文献
97.
98.
Cayo Emilio Gonçalves Letícia Oliveira Laier Márcio José da Silva 《Catalysis Letters》2011,141(8):1111-1117
Abstract
In this work, a novel process based on use of a SnCl2·2H2O catalyst which is less corrosive, inexpensive, and a water tolerant Lewis acid was employed for synthesis of fuel bio-additives from glycerol. High yields and selectivities were achieved for glycerol esterification with acetic acid under mild reaction conditions. The SnCl2 catalyst showed to be as active as p-toluene sulfonic and sulfuric acid, catalysts commonly used in acid-catalysed esterification reactions. However, its use has significant advantages in comparison to these Br?nsted acid catalysts, including lower reactor corrosion and unnecessary neutralization at the end reaction. The SnCl2 catalyst can also be recovered and reused without loss of catalytic activity. Additionally, effects of reaction temperature, HOAc:glycerol molar ratio and catalyst concentration on both selectivity and yield of glycerol acetates were also investigated. The lower corrosiveness, facilitated handling, as well as potential for reuse without activity loss after simple recycle protocols are positive aspects of SnCl2 catalysts. 相似文献99.
Combining Upscaling and Downscaling of Methane Emissions from Rice Fields: Methodologies and Preliminary Results 总被引:1,自引:0,他引:1
H.A.C. Denier van der Gon P.M. van Bodegom S. Houweling P.H. Verburg N. van Breemen 《Nutrient Cycling in Agroecosystems》2000,58(1-3):285-301
The uncertainty in the methane (CH4) source strength of rice fields is among the highest of all sources in the global CH4 budget. Methods to estimate the source strength of rice fields can be divided into two scaling categories: bottom-up (upscaling) and top-down (downscaling). A brief review of upscaling and downscaling methodologies is presented. The combination of upscaling and downscaling methodologies is proposed as a potential method to reduce the uncertainty in the regional CH4 source strength of rice fields. Some preliminary results based on upscaling and downscaling are presented and the limitations of the approaches are discussed. The first case study focuses on upscaling by using a field-scale model in combination with spatial databases to calculate CH4 emissions for the island of Java. The reliability of upscaling results is limited by the uncertainty in model input parameters such as soil properties and organic carbon management. Because controlling variables such as harvested rice area may change on relatively short time scales, a land use change model (CLUE) was used to quantify the potential land use changes on Java in the period 1994–2010. The predicted changes were evaluated using the CH4 emission model. Temporal scaling by coupling land use change models and emission models is necessary to answer policy-related questions on future greenhouse gas emissions. In a downscaling case study, we investigate if inverse modeling can constrain the emissions from rice fields by testing a standard CH4 from rice scenario and a low CH4 from rice scenario (80 and 30 Tg CH4 yr–1, respectively). The results of this study are not yet conclusive; to obtain fine-resolution CH4 emission estimates over the Southeast Asian continent, the monitoring network atmospheric mixturing ratios need to be extended and located closer to the continental sources. 相似文献
100.
R Santos F Oliveira J Fernandes S Gon?alves F Macieira M Cadete 《Water science and technology》2005,52(8):177-180
Mycobacteria have emerged as a major cause of opportunistic infections. Until the present, only a few studies have characterized mycobacteria present in the water distribution system of urban areas. In this study, we characterize these microorganisms in the Lisbon water distribution system. Our results indicate a high rate of positivities (90.5%) with mainly saprophytic mycobacteria. Around 63% of these results belong to strains of Mycobacterium gordonae indicating a generalized proliferation of this species in the Lisbon water distribution system. A total of 21.05% of the isolates are from M. kansasii, M. intracellulare and M. chelonae. 相似文献