1,583 research outputs found
Scale Normalization for the Distance Maps AAM
International audienceThe Active Apearence Models (AAM) are often used in Man-Machine Interaction for their ability to align the faces. We propose a new normalization method for AAM based on distance map in order to strengthen their robustness to differences in illumination. Our normalization do not use the photometric normalization protocol classically used in AAM and is much more simpler to implement. Compared to Distance Map AAM performances of {Leg06} and other AAM implementation which use CLAHE {Zuiderveld94} normalization or gradient information, our proposition is at the same time much robust to illumination and AAM initialization. The tests have been drive in the context of generalization: 10 persons with frontal illumination from M2VTS database {m2vts} were considered to build the AAM, and 17 persons under 21 different illuminations from CMU database {Sim02} were used for the testing base
Assisting pre-big bang phenomenology through short-lived axions
We present the results of a detailed study of how isocurvature axion
fluctuations are converted into adiabatic metric perturbations through axion
decay, and discuss the constraints on the parameters of pre-big bang cosmology
needed for consistency with present CMB-anisotropy data. The large-scale
normalization of temperature fluctuations has a non-trivial dependence both on
the mass and on the initial value of the axion. In the simplest, minimal models
of pre-big bang inflation, consistency with the COBE normalization requires a
slightly tilted (blue) spectrum, while a strictly scale-invariant spectrum
requires mild modifications of the minimal backgrounds at large curvature
and/or string coupling.Comment: 14 pages, latex, 1 figure included using epsfig. A few typos
corrected, two references added, the figure slightly improved. To appear in
Phys. Lett.
Multi-view 3D retrieval using silhouette intersection and multi-scale contour representation
We describe in this paper two methods for 3D shape indexing
and retrieval that we apply on two data collections
of the SHREC - SHape Retrieval Contest 2007: Watertight
models and 3D CAD models. Both methods are based on a
set of 2D multi-views after a pose and scale normalization
of the models using PCA and the enclosing sphere. In all
views we extract the models silhouettes and compare them
pairwise. In the first method the similitude measure is obtained by integrating on the pairs of views the difference between the areas of the silhouettes union and the silhouettes intersection. In the second method we consider the external contour of the silhouettes, extract their convexities and concavities at different scale levels and build a multiscale representation. The pairs of contours are then compared by elastic matching achieved by using dynamic programming. Comparisons of the two methods are shown with their respective strengths and weaknesses
An Analysis of Scale Invariance in Object Detection - SNIP
An analysis of different techniques for recognizing and detecting objects
under extreme scale variation is presented. Scale specific and scale invariant
design of detectors are compared by training them with different configurations
of input data. By evaluating the performance of different network architectures
for classifying small objects on ImageNet, we show that CNNs are not robust to
changes in scale. Based on this analysis, we propose to train and test
detectors on the same scales of an image-pyramid. Since small and large objects
are difficult to recognize at smaller and larger scales respectively, we
present a novel training scheme called Scale Normalization for Image Pyramids
(SNIP) which selectively back-propagates the gradients of object instances of
different sizes as a function of the image scale. On the COCO dataset, our
single model performance is 45.7% and an ensemble of 3 networks obtains an mAP
of 48.3%. We use off-the-shelf ImageNet-1000 pre-trained models and only train
with bounding box supervision. Our submission won the Best Student Entry in the
COCO 2017 challenge. Code will be made available at
\url{http://bit.ly/2yXVg4c}.Comment: CVPR 2018, camera ready versio
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