208,713 research outputs found
Shape-appearance-correlated active appearance model
© 2016 Elsevier Ltd Among the challenges faced by current active shape or appearance models, facial-feature localization in the wild, with occlusion in a novel face image, i.e. in a generic environment, is regarded as one of the most difficult computer-vision tasks. In this paper, we propose an Active Appearance Model (AAM) to tackle the problem of generic environment. Firstly, a fast face-model initialization scheme is proposed, based on the idea that the local appearance of feature points can be accurately approximated with locality constraints. Nearest neighbors, which have similar poses and textures to a test face, are retrieved from a training set for constructing the initial face model. To further improve the fitting of the initial model to the test face, an orthogonal CCA (oCCA) is employed to increase the correlation between shape features and appearance features represented by Principal Component Analysis (PCA). With these two contributions, we propose a novel AAM, namely the shape-appearance-correlated AAM (SAC-AAM), and the optimization is solved by using the recently proposed fast simultaneous inverse compositional (Fast-SIC) algorithm. Experiment results demonstrate a 5–10% improvement on controlled and semi-controlled datasets, and with around 10% improvement on wild face datasets in terms of fitting accuracy compared to other state-of-the-art AAM models
Relating Objective and Subjective Performance Measures for AAM-based Visual Speech Synthesizers
We compare two approaches for synthesizing visual speech using Active Appearance Models (AAMs): one that utilizes acoustic features as input, and one that utilizes a phonetic transcription as input. Both synthesizers are trained using the same data and the performance is measured using both objective and subjective testing. We investigate the impact of likely sources of error in the synthesized visual speech by introducing typical errors into real visual speech sequences and subjectively measuring the perceived degradation. When only a small region (e.g. a single syllable) of ground-truth visual speech is incorrect we find that the subjective score for the entire sequence is subjectively lower than sequences generated by our synthesizers. This observation motivates further consideration of an often ignored issue, which is to what extent are subjective measures correlated with objective measures of performance? Significantly, we find that the most commonly used objective measures of performance are not necessarily the best indicator of viewer perception of quality. We empirically evaluate alternatives and show that the cost of a dynamic time warp of synthesized visual speech parameters to the respective ground-truth parameters is a better indicator of subjective quality
Prostate MR image segmentation using 3D active appearance models
This paper presents a method for automatic segmentation of the prostate from transversal T2-weighted images based on 3D Active Appearance Models (AAM). The algorithm consist of two stages. Firstly, Shape Context based non-rigid surface registration of the manual segmented images is used to obtain the point correspondence between the given training cases. Subsequently, an AAM is used to segment the prostate on 50 training cases. The method is evaluated using a 5-fold cross validation over 5 repetitions. The mean Dice similarity coefficient and 95% Hausdorff distance are 0.78 and 7.32 mm respectively
Analysing the importance of different visual feature coefficients
A study is presented to determine the relative importance of different visual features for speech recognition which includes pixel-based, model-based, contour-based and physical features. Analysis to determine the discriminability of features is per- formed through F-ratio and J-measures for both static and tem- poral derivatives, the results of which were found to correlate highly with speech recognition accuracy (r = 0.97). Princi- pal component analysis is then used to combine all visual fea- tures into a single feature vector, of which further analysis is performed on the resulting basis functions. An optimal feature vector is obtained which outperforms the best individual feature (AAM) with 93.5 % word accuracy
Updated Global 3+1 Analysis of Short-BaseLine Neutrino Oscillations
We present the results of an updated fit of short-baseline neutrino
oscillation data in the framework of 3+1 active-sterile neutrino mixing. We
first consider and disappearance in the light of the
Gallium and reactor anomalies. We discuss the implications of the recent
measurement of the reactor spectrum in the NEOS experiment, which
shifts the allowed regions of the parameter space towards smaller values of
. The beta-decay constraints allow us to limit the oscillation
length between about 2 cm and 7 m at for neutrinos with an energy of
1 MeV. We then consider the global fit of the data in the light of the LSND
anomaly, taking into account the constraints from and
disappearance experiments, including the recent data of the MINOS and IceCube
experiments. The combination of the NEOS constraints on and the
MINOS and IceCube constraints on lead to an unacceptable
appearance-disappearance tension which becomes tolerable only in a pragmatic
fit which neglects the MiniBooNE low-energy anomaly. The minimization of the
global in the space of the four mixing parameters ,
, , and leads to three allowed
regions with narrow widths at (best-fit), 1.3 (at ), 2.4 (at ) eV. The
restrictions of the allowed regions of the mixing parameters with respect to
our previous global fits are mainly due to the NEOS constraints. We present a
comparison of the allowed regions of the mixing parameters with the
sensitivities of ongoing experiments, which show that it is likely that these
experiments will determine in a definitive way if the reactor, Gallium and LSND
anomalies are due to active-sterile neutrino oscillations or not.Comment: 39 pages; improved treatment of the reactor flux uncertainties and
other minor correction
Ensemble of Hankel Matrices for Face Emotion Recognition
In this paper, a face emotion is considered as the result of the composition
of multiple concurrent signals, each corresponding to the movements of a
specific facial muscle. These concurrent signals are represented by means of a
set of multi-scale appearance features that might be correlated with one or
more concurrent signals. The extraction of these appearance features from a
sequence of face images yields to a set of time series. This paper proposes to
use the dynamics regulating each appearance feature time series to recognize
among different face emotions. To this purpose, an ensemble of Hankel matrices
corresponding to the extracted time series is used for emotion classification
within a framework that combines nearest neighbor and a majority vote schema.
Experimental results on a public available dataset shows that the adopted
representation is promising and yields state-of-the-art accuracy in emotion
classification.Comment: Paper to appear in Proc. of ICIAP 2015. arXiv admin note: text
overlap with arXiv:1506.0500
The LSND and MiniBooNE Oscillation Searches at High
This paper reviews the results of the LSND and MiniBooNE experiments. The
primary goal of each experiment was to effect sensitive searches for neutrino
oscillations in the mass region with eV. The two
experiments are complementary, and so the comparison of results can bring
additional information with respect to models with sterile neutrinos. Both
experiments obtained evidence for
oscillations, and MiniBooNE also observed a excess.
In this paper, we review the design, analysis, and results from these
experiments. We then consider the results within the global context of sterile
neutrino oscillation models. The final data sets require a more extended model
than the simple single sterile neutrino model imagined at the time that LSND
drew to a close and MiniBooNE began. We show that there are apparent
incompatibilities between data sets in models with two sterile neutrinos.
However, these incompatibilities may be explained with variations within the
systematic error. Overall, models with two (or three) sterile neutrinos seem to
succeed in fitting the global data, and they make interesting predictions for
future experiments.Comment: Posted with permission from the Annual Review of Nuclear and Particle
Science, Volume 63. \c{opyright} 2013 by Annual Reviews,
http://www.annualreviews.or
Light Sterile Neutrinos in Particle Physics: Experimental Status
Most of the neutrino oscillation results can be explained by the
three-neutrino paradigm. However several anomalies in short baseline
oscillation data could be interpreted by invoking a hypothetical fourth
neutrino, separated from the three standard neutrinos by a squared mass
difference of more than 0.1 eV. This new neutrino, often called sterile,
would not feel standard model interactions but mix with the others. Such a
scenario calling for new physics beyond the standard model has to be either
ruled out or confirmed with new data. After a brief review of the anomalous
oscillation results we discuss the world-wide experimental proposal aiming to
clarify the situation.Comment: 14 pages, 2 figures. To appear in the proceedings of the 13th
International Conference on Topics in Astroparticle and Underground Physics,
TAUP 2013 (F. Avignone & W. Haxton, editors, Physics Procedia, Elsevier) ;
Minor revisions in version
3D Face tracking and gaze estimation using a monocular camera
Estimating a user’s gaze direction, one of the main novel user interaction technologies, will eventually be used for numerous applications where current methods are becoming less effective. In this paper, a new method is presented for estimating the gaze direction using Canonical Correlation Analysis (CCA), which finds a linear relationship between two datasets defining the face pose and the corresponding facial appearance changes. Afterwards, iris tracking is performed by blob detection using a 4-connected component labeling algorithm. Finally, a gaze vector is calculated based on gathered eye properties. Results obtained from datasets and real-time input confirm the robustness of this metho
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