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941.
Carlos Ricolfe-Viala Author Vitae Antonio-José Sánchez-Salmerón Author Vitae 《Pattern recognition》2010,43(4):1688-1699
Camera lens distortion is crucial to obtain the best performance cameral model. Up to now, different techniques exist, which try to minimize the calibration error using different lens distortion models or computing them in different ways. Some compute lens distortion camera parameters in the camera calibration process together with the intrinsic and extrinsic ones. Others isolate the lens distortion calibration without using any template and basing the calibration on the deformation in the image of some features of the objects in the scene, like straight lines or circles. These lens distortion techniques which do not use any calibration template can be unstable if a complete camera lens distortion model is computed. They are named non-metric calibration or self-calibration methods.Traditionally a camera has been always best calibrated if metric calibration is done instead of self-calibration. This paper proposes a metric calibration technique which computes the camera lens distortion isolated from the camera calibration process under stable conditions, independently of the computed lens distortion model or the number of parameters. To make it easier to resolve, this metric technique uses the same calibration template that will be used afterwards for the calibration process. Therefore, the best performance of the camera lens distortion calibration process is achieved, which is transferred directly to the camera calibration process. 相似文献
942.
Julián D. Arias-Londoño Author Vitae Juan I. Godino-Llorente Author Vitae Nicolás Sáenz-Lechón Author Vitae Author Vitae Germán Castellanos-Domínguez Author Vitae 《Pattern recognition》2010,43(9):3100-3112
This paper presents new a feature transformation technique applied to improve the screening accuracy for the automatic detection of pathological voices. The statistical transformation is based on Hidden Markov Models, obtaining a transformation and classification stage simultaneously and adjusting the parameters of the model with a criterion that minimizes the classification error. The original feature vectors are built up using classic short-term noise parameters and mel-frequency cepstral coefficients. With respect to conventional approaches found in the literature of automatic detection of pathological voices, the proposed feature space transformation technique demonstrates a significant improvement of the performance with no addition of new features to the original input space. In view of the results, it is expected that this technique could provide good results in other areas such as speaker verification and/or identification. 相似文献
943.
Automatic metro map layout using multicriteria optimization 总被引:1,自引:0,他引:1
Stott J Rodgers P Martínez-Ovando JC Walker SG 《IEEE transactions on visualization and computer graphics》2011,17(1):101-114
This paper describes an automatic mechanism for drawing metro maps. We apply multicriteria optimization to find effective placement of stations with a good line layout and to label the map unambiguously. A number of metrics are defined, which are used in a weighted sum to find a fitness value for a layout of the map. A hill climbing optimizer is used to reduce the fitness value, and find improved map layouts. To avoid local minima, we apply clustering techniques to the map-the hill climber moves both stations and clusters when finding improved layouts. We show the method applied to a number of metro maps, and describe an empirical study that provides some quantitative evidence that automatically-drawn metro maps can help users to find routes more efficiently than either published maps or undistorted maps. Moreover, we have found that, in these cases, study subjects indicate a preference for automatically-drawn maps over the alternatives. 相似文献
944.
Javier Sánchez-Monedero Pedro A. Gutiérrez F. Fernández-Navarro C. Hervás-Martínez 《Neural Processing Letters》2011,34(2):101-116
Recently, a multi-objective Sensitivity–Accuracy based methodology has been proposed for building classifiers for multi-class problems. This technique is especially suitable for imbalanced and multi-class datasets. Moreover, the high computational cost of multi-objective approaches is well known so more efficient alternatives must be explored. This paper presents an efficient alternative to the Pareto based solution when considering both Minimum Sensitivity and Accuracy in multi-class classifiers. Alternatives are implemented by extending the Evolutionary Extreme Learning Machine algorithm for training artificial neural networks. Experiments were performed to select the best option after considering alternative proposals and related methods. Based on the experiments, this methodology is competitive in Accuracy, Minimum Sensitivity and efficiency. 相似文献
945.
Juli��n Luengo Alberto Fern��ndez Salvador Garc��a Francisco Herrera 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2011,15(10):1909-1936
In the classification framework there are problems in which the number of examples per class is not equitably distributed,
formerly known as imbalanced data sets. This situation is a handicap when trying to identify the minority classes, as the
learning algorithms are not usually adapted to such characteristics. An usual approach to deal with the problem of imbalanced
data sets is the use of a preprocessing step. In this paper we analyze the usefulness of the data complexity measures in order
to evaluate the behavior of undersampling and oversampling methods. Two classical learning methods, C4.5 and PART, are considered
over a wide range of imbalanced data sets built from real data. Specifically, oversampling techniques and an evolutionary
undersampling one have been selected for the study. We extract behavior patterns from the results in the data complexity space
defined by the measures, coding them as intervals. Then, we derive rules from the intervals that describe both good or bad
behaviors of C4.5 and PART for the different preprocessing approaches, thus obtaining a complete characterization of the data
sets and the differences between the oversampling and undersampling results. 相似文献
946.
A non-intrusive estimation for high-quality Internet TV services 总被引:1,自引:0,他引:1
Alberto?Fraga Laura?Pozueco Xabiel?Garcia Pa?edaEmail author Roberto?García David?Melendi Sergio?Cabrero 《Multimedia Tools and Applications》2011,54(3):569-588
This paper presents a non-intrusive estimator for Internet TV services based on streaming technology. Analyzing the video
packets received by the client application, the estimator is capable of selecting the most suitable encoding bitrate for the
available bandwidth in the end-to-end path. The estimator has been integrated in a real client/server architecture and evaluated
with different network traffic situations. The results of the performed evaluation have revealed the stability and adaptation
speed as the best qualities of our proposal. 相似文献
947.
948.
Local feature-based approaches mainly aim to achieve robustness to variations in facial images by assuming that only some
parts of the facial images may be affected. However, such approaches may lose spatial information. In this study, a compromise
feature extraction scheme is studied which extracts local features while preserving spatial information. The proposed scheme
exploits an ensemble of classifiers where each member is constructed using randomly selected design parameters including the
size, number and location of sub-images for local feature extraction. Experiments conducted on FERET and ORL databases have
shown that proposed scheme surpasses the local feature-based reference systems which focus on either local information or
preserving spatial information. 相似文献
949.
Diego Castaño José Patricio Díaz Varela Antoni Torrens 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2011,15(7):1449-1455
In this paper, we show that free algebras in the variety of residuated lattices and some of its subvarieties are directly
indecomposable and show, as a consequence, the direct indecomposability of free algebras for some classes of their bounded
implicative subreducts. 相似文献
950.
The localization of the components of an object near to a device before obtaining the real interaction is usually determined by means of a proximity measurement to the device of the object’s features. In order to do this efficiently, hierarchical decompositions are used, so that the features of the objects are classified into several types of cells, usually rectangular.In this paper we propose a solution based on the classification of a set of points situated on the device in a little-known spatial decomposition named tetra-tree. Using this type of spatial decomposition gives us several quantitative and qualitative properties that allow us a more realistic and intuitive visual interaction, as well as the possibility of selecting inaccessible components. These features could be used in virtual sculpting or accessibility tasks.In order to show these properties we have compared an interaction system based on tetra-trees to one based on octrees. 相似文献