28,925 research outputs found
Face Detection with Effective Feature Extraction
There is an abundant literature on face detection due to its important role
in many vision applications. Since Viola and Jones proposed the first real-time
AdaBoost based face detector, Haar-like features have been adopted as the
method of choice for frontal face detection. In this work, we show that simple
features other than Haar-like features can also be applied for training an
effective face detector. Since, single feature is not discriminative enough to
separate faces from difficult non-faces, we further improve the generalization
performance of our simple features by introducing feature co-occurrences. We
demonstrate that our proposed features yield a performance improvement compared
to Haar-like features. In addition, our findings indicate that features play a
crucial role in the ability of the system to generalize.Comment: 7 pages. Conference version published in Asian Conf. Comp. Vision
201
Efficient Object Localization Using Convolutional Networks
Recent state-of-the-art performance on human-body pose estimation has been
achieved with Deep Convolutional Networks (ConvNets). Traditional ConvNet
architectures include pooling and sub-sampling layers which reduce
computational requirements, introduce invariance and prevent over-training.
These benefits of pooling come at the cost of reduced localization accuracy. We
introduce a novel architecture which includes an efficient `position
refinement' model that is trained to estimate the joint offset location within
a small region of the image. This refinement model is jointly trained in
cascade with a state-of-the-art ConvNet model to achieve improved accuracy in
human joint location estimation. We show that the variance of our detector
approaches the variance of human annotations on the FLIC dataset and
outperforms all existing approaches on the MPII-human-pose dataset.Comment: 8 pages with 1 page of citation
More on the Subtraction Algorithm
We go on in the program of investigating the removal of divergences of a
generical quantum gauge field theory, in the context of the Batalin-Vilkovisky
formalism. We extend to open gauge-algebrae a recently formulated algorithm,
based on redefinitions of the parameters of the
classical Lagrangian and canonical transformations, by generalizing a well-
known conjecture on the form of the divergent terms. We also show that it is
possible to reach a complete control on the effects of the subtraction
algorithm on the space of the gauge-fixing parameters. A
principal fiber bundle with a connection
is defined, such that the canonical transformations are gauge
transformations for . This provides an intuitive geometrical
description of the fact the on shell physical amplitudes cannot depend on
. A geometrical description of the effect of the subtraction
algorithm on the space of the physical parameters is
also proposed. At the end, the full subtraction algorithm can be described as a
series of diffeomorphisms on , orthogonal to
(under which the action transforms as a scalar), and gauge transformations on
. In this geometrical context, a suitable concept of predictivity is
formulated. We give some examples of (unphysical) toy models that satisfy this
requirement, though being neither power counting renormalizable, nor finite.Comment: LaTeX file, 37 pages, preprint SISSA/ISAS 90/94/E
Nonextensive entropy approach to space plasma fluctuations and turbulence
Spatial intermittency in fully developed turbulence is an established feature
of astrophysical plasma fluctuations and in particular apparent in the
interplanetary medium by in situ observations. In this situation the classical
Boltzmann-Gibbs extensive thermo-statistics, applicable when microscopic
interactions and memory are short ranged, fails. Upon generalization of the
entropy function to nonextensivity, accounting for long-range interactions and
thus for correlations in the system, it is demonstrated that the corresponding
probability distributions (PDFs) are members of a family of specific power-law
distributions. In particular, the resulting theoretical bi-kappa functional
reproduces accurately the observed global leptokurtic, non-Gaussian shape of
the increment PDFs of characteristic solar wind variables on all scales.
Gradual decoupling is obtained by enhancing the spatial separation scale
corresponding to increasing kappa-values in case of slow solar wind conditions
where a Gaussian is approached in the limit of large scales. Contrary, the
scaling properties in the high speed solar wind are predominantly governed by
the mean energy or variance of the distribution. The PDFs of solar wind scalar
field differences are computed from WIND and ACE data for different time-lags
and bulk speeds and analyzed within the nonextensive theory. Consequently,
nonlocality in fluctuations, related to both, turbulence and its large scale
driving, should be related to long-range interactions in the context of
nonextensive entropy generalization, providing fundamentally the physical
background of the observed scale dependence of fluctuations in intermittent
space plasmas.Comment: 21 pages, 8 figures, accepted for publication, to appear in Advances
in Geosciences 2, chapter 04, 2006 (with minor corrections
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