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51.
The bilateral filter is a nonlinear filter that smoothes a signal while preserving strong edges. It has demonstrated great
effectiveness for a variety of problems in computer vision and computer graphics, and fast versions have been proposed. Unfortunately,
little is known about the accuracy of such accelerations. In this paper, we propose a new signal-processing analysis of the
bilateral filter which complements the recent studies that analyzed it as a PDE or as a robust statistical estimator. The
key to our analysis is to express the filter in a higher-dimensional space where the signal intensity is added to the original
domain dimensions. Importantly, this signal-processing perspective allows us to develop a novel bilateral filtering acceleration
using downsampling in space and intensity. This affords a principled expression of accuracy in terms of bandwidth and sampling.
The bilateral filter can be expressed as linear convolutions in this augmented space followed by two simple nonlinearities.
This allows us to derive criteria for downsampling the key operations and achieving important acceleration of the bilateral
filter. We show that, for the same running time, our method is more accurate than previous acceleration techniques. Typically,
we are able to process a 2 megapixel image using our acceleration technique in less than a second, and have the result be
visually similar to the exact computation that takes several tens of minutes. The acceleration is most effective with large
spatial kernels. Furthermore, this approach extends naturally to color images and cross bilateral filtering. 相似文献
52.
A.B. Moreno A. Sánchez E. Frías-Martínez J.F. Vélez 《Engineering Applications of Artificial Intelligence》2009,22(8):1233-1244
Applications related to game technology, law-enforcement, security, medicine or biometrics are becoming increasingly important, which, combined with the proliferation of three-dimensional (3D) scanning hardware, have made that 3D face recognition is now becoming a promising and feasible alternative to two-dimensional (2D) face methods. The main advantage of 3D data, when compared with traditional 2D approaches, is that it provides information that is invariant to rigid geometric transformations and to pose and illumination conditions. One key element for any 3D face recognition system is the modeling of the available scanned data. This paper presents new 3D models for facial surface representation and evaluates them using two matching approaches: one based on support vector machines and another one on principal component analysis (with a Euclidean classifier). Also, two types of environments were tested in order to check the robustness of the proposed models: a controlled environment with respect to facial conditions (i.e. expressions, face rotations, etc.) and a non-controlled one (presenting face rotations and pronounced facial expressions). The recognition rates obtained using reduced spatial resolution representations (a 77.86% for non-controlled environments and a 90.16% for controlled environments, respectively) show that the proposed models can be effectively used for practical face recognition applications. 相似文献
53.
Christiane Jasmin Reinert‐Weiss Holger Baur Sheikh Abdullah Al Nusayer David Duhme Norbert Frühauf 《Journal of the Society for Information Display》2017,25(2):90-97
Conventional adaptive driving beam headlamps are limited in achieving still higher quantities of switchable pixels by the number of LEDs and movable elements needed. In this paper, it is shown that by integrating an active matrix liquid crystal display module, it is possible to realize fully adaptive high‐resolution headlights without mechanical elements and a finite number of LED with 30 k switchable pixels. 相似文献
54.
Road‐Centered Map‐Aided Localization for Driverless Cars Using Single‐Frequency GNSS Receivers
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Zui Tao Philippe Bonnifait Vincent Frémont Javier Ibanez‐Guzman Stéphane Bonnet 《野外机器人技术杂志》2017,34(5):1010-1033
Accurate localization with high availability is a key requirement for autonomous vehicles. It remains a major challenge when using automotive sensors such as single‐frequency Global Navigation Satellite System (GNSS) receivers, a lane detection camera, and proprioceptive sensors. This paper describes a method that enables the estimation of stand‐alone single‐frequency GNSS errors by integrating the measurements from a forward‐looking camera matched with lane markings stored in a digital map. It includes a parameter identification method for a shaping model, which is evaluated using experimental data. An algebraic observability study is then conducted to prove that the proposed state vector is fully observable in a road‐oriented frame. This observability property is the basis to develop a road‐centered Extended Kalman filter (EKF) that can maintain the observability of every component of the state vector on any road, whatever its orientation. To accomplish this, the filter needs to handle road changes, which it does using bijective transformations. The filter was implemented and tested intensely on an experimental vehicle for driverless valet parking services. Field results have shown that the performance of the estimation process is better than solutions based on EKF implemented in a fixed working frame. The proposed filter guarantees that the drift along the road direction remains bounded. This is very important when the vehicle navigates autonomously. Furthermore, the road‐centered modeling improves the accuracy, consistency, and robustness of the localization solver. 相似文献
55.
Simultaneous automated design of structured QFT controller and prefilter using nonlinear programming
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Harsh Purohit Alexandre Goldsztejn Christophe Jermann Laurent Granvilliers Frédéric Goualard P. S. V. Nataraj Bhagyesh Patil 《国际强度与非线性控制杂志
》2017,27(15):2529-2548
》2017,27(15):2529-2548
This paper describes a nonlinear programming‐based robust design methodology for controllers and prefilters of a predefined structure for the linear time‐invariant systems involved in the quantitative feedback theory. This controller and prefilter synthesis problem is formulated as a single optimization problem with a given performance optimization objective and constraints enforcing stability and various specifications usually enforced in the quantitative feedback theory. The focus is set on providing constraints expression that can be used in standard nonlinear programming solvers. The nonlinear solver then computes in a single‐step controller and prefilter design parameters that satisfy the prescribed constraints and maximizes the performance optimization objective. The effectiveness of the proposed approach is demonstrated through a variety of difficult design cases like resonant plants, open‐loop unstable plants, and plants with variation in the time delay. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
56.
Frédéric Havet Martin Klazar Jan Kratochvíl Dieter Kratsch Mathieu Liedloff 《Algorithmica》2011,59(2):169-194
The notion of distance constrained graph labelings, motivated by the Frequency Assignment Problem, reads as follows: A mapping
from the vertex set of a graph G=(V,E) into an interval of integers {0,…,k} is an L(2,1)-labeling of G of span k if any two adjacent vertices are mapped onto integers that are at least 2 apart, and every two vertices with a common neighbor
are mapped onto distinct integers. It is known that for any fixed k≥4, deciding the existence of such a labeling is an NP-complete problem. We present exact exponential time algorithms that
are faster than the naive O
*((k+1)
n
) algorithm that would try all possible mappings. The improvement is best seen in the first NP-complete case of k=4, where the running time of our algorithm is O(1.3006
n
). Furthermore we show that dynamic programming can be used to establish an O(3.8730
n
) algorithm to compute an optimal L(2,1)-labeling. 相似文献
57.
Frédéric Cuppens Nora Cuppens-Boulahia 《International Journal of Information Security》2008,7(4):285-305
As computer infrastructures become more complex, security models must provide means to handle more flexible and dynamic requirements.
In the Organization Based Access Control (OrBAC) model, it is possible to express such requirements using the notion of context.
In OrBAC, each security rule (permission, prohibition, obligation or dispensation) only applies in a given context. A context
is viewed as an extra condition that must be satisfied to activate a given security rule. In this paper, we present a taxonomy
of different types of context and investigate the data the information system must manage in order to deal with these different
contexts. We then explain how to model and evaluate them in the OrBAC model.
相似文献
Nora Cuppens-BoulahiaEmail: |
58.
Frédéric Mallet 《Innovations in Systems and Software Engineering》2008,4(3):309-314
The Object Management Group (OMG) unified modeling language (UML) profile for modeling and analysis of real-time and embedded
systems (MARTE) aims at using the general-purpose modeling language UML in the domain of real-time and embedded (RTE) systems.
To achieve this goal, it is absolutely required to introduce inside the mainly untimed UML an unambiguous time structure which
MARTE model elements can rely on to build precise models amenable to formal analysis. The MARTE Time model has defined such
a structure. We have also defined a non-normative concrete syntax called the clock constraint specification language (CCSL)
to demonstrate what can be done based on this structure. This paper gives a brief overview of this syntax and its formal semantics,
and shows how existing UML model elements can be used to apply this syntax in a graphical way and benefit from the semantics. 相似文献
59.
Cunin F Milhiet PE Anglin E Sailor MJ Espenel C Le Grimellec C Brunel D Devoisselle JM 《Ultramicroscopy》2007,107(10-11):1048-1052
Reconstituting artificial membranes for in vitro studies of cell barrier mechanisms and properties is of major interest in biology. Here, artificial membranes supported on porous silicon photonic crystal reflectors are prepared and investigated. The materials are of interest for label-free probing of supported membrane events such as protein binding, molecular recognition, and transport. The porous silicon substrates are prepared as multilayered films consisting of a periodically varying porosity, with pore dimensions of a few nanometers in size. Planar phospholipid bilayers are deposited on the topmost surface of the oxidized hydrophilic mesoporous silicon films. Atomic force microscopy provides evidence of continuous bilayer deposition at the surface, and optical measurements indicate that the lipids do not significantly infiltrate the porous region. The presence of the supported bilayer does not obstruct the optical spectrum from the porous silicon layer, suggesting that the composite structures can act as effective optical biosensors. 相似文献
60.
We consider the edit distance with moves on the class of words and the class of ordered trees. We first exhibit a simple tester
for the class of regular languages on words and generalize it to the class of ranked and unranked regular trees. We also show
that this distance problem is
-complete on ordered trees.
A preliminary version of this paper appeared in Proceedings of 31st International Colloquium on Automata, Languages and Programming, volume 3142 of Lecture Notes in Computer Science, pages 932–944, Springer, 2005. Work supported by ACI Sécurité Informatique: VERA of the French Ministry of research. 相似文献