32,808 research outputs found
Rejection-Cascade of Gaussians: Real-time adaptive background subtraction framework
Background-Foreground classification is a well-studied problem in computer
vision. Due to the pixel-wise nature of modeling and processing in the
algorithm, it is usually difficult to satisfy real-time constraints. There is a
trade-off between the speed (because of model complexity) and accuracy.
Inspired by the rejection cascade of Viola-Jones classifier, we decompose the
Gaussian Mixture Model (GMM) into an adaptive cascade of Gaussians(CoG). We
achieve a good improvement in speed without compromising the accuracy with
respect to the baseline GMM model. We demonstrate a speed-up factor of 4-5x and
17 percent average improvement in accuracy over Wallflowers surveillance
datasets. The CoG is then demonstrated to over the latent space representation
of images of a convolutional variational autoencoder(VAE). We provide initial
results over CDW-2014 dataset, which could speed up background subtraction for
deep architectures.Comment: Accepted for National Conference on Computer Vision, Pattern
Recognition, Image Processing and Graphics (NCVPRIPG 2019
The Discovery of Cometary Activity in Near-Earth Asteroid (3552) Don Quixote
The near-Earth object (NEO) population, which mainly consists of fragments
from collisions between asteroids in the main asteroid belt, is thought to
include contributions from short-period comets as well. One of the most
promising NEO candidates for a cometary origin is near-Earth asteroid (3552)
Don Quixote, which has never been reported to show activity. Here we present
the discovery of cometary activity in Don Quixote based on thermal-infrared
observations made with the Spitzer Space Telescope in its 3.6 and 4.5 {\mu}m
bands. Our observations clearly show the presence of a coma and a tail in the
4.5 {\mu}m but not in the 3.6 {\mu}m band, which is consistent with molecular
band emission from CO2. Thermal modeling of the combined photometric data on
Don Quixote reveals a diameter of 18.4 (-0.4/+0.3) km and an albedo of 0.03
(-0.01/+0.02), which confirms Don Quixote to be the third-largest known NEO. We
derive an upper limit on the dust production rate of 1.9 kg s^-1 and derive a
CO2 gas production rate of (1.1+-0.1)10^26 molecules s^-1. Spitzer IRS
spectroscopic observations indicate the presence of fine-grained silicates,
perhaps pyroxene rich, on the surface of Don Quixote. Our discovery suggests
that CO2 can be present in near-Earth space over a long time. The presence of
CO2 might also explain that Don Quixote's cometary nature remained hidden for
nearly three decades.Comment: 40 pages, 8 figures, accepted by Ap
A generic framework for video understanding applied to group behavior recognition
This paper presents an approach to detect and track groups of people in
video-surveillance applications, and to automatically recognize their behavior.
This method keeps track of individuals moving together by maintaining a spacial
and temporal group coherence. First, people are individually detected and
tracked. Second, their trajectories are analyzed over a temporal window and
clustered using the Mean-Shift algorithm. A coherence value describes how well
a set of people can be described as a group. Furthermore, we propose a formal
event description language. The group events recognition approach is
successfully validated on 4 camera views from 3 datasets: an airport, a subway,
a shopping center corridor and an entrance hall.Comment: (20/03/2012
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