11,183 research outputs found
Joint Detection and Tracking in Videos with Identification Features
Recent works have shown that combining object detection and tracking tasks,
in the case of video data, results in higher performance for both tasks, but
they require a high frame-rate as a strict requirement for performance. This is
assumption is often violated in real-world applications, when models run on
embedded devices, often at only a few frames per second.
Videos at low frame-rate suffer from large object displacements. Here
re-identification features may support to match large-displaced object
detections, but current joint detection and re-identification formulations
degrade the detector performance, as these two are contrasting tasks. In the
real-world application having separate detector and re-id models is often not
feasible, as both the memory and runtime effectively double.
Towards robust long-term tracking applicable to reduced-computational-power
devices, we propose the first joint optimization of detection, tracking and
re-identification features for videos. Notably, our joint optimization
maintains the detector performance, a typical multi-task challenge. At
inference time, we leverage detections for tracking (tracking-by-detection)
when the objects are visible, detectable and slowly moving in the image. We
leverage instead re-identification features to match objects which disappeared
(e.g. due to occlusion) for several frames or were not tracked due to fast
motion (or low-frame-rate videos). Our proposed method reaches the
state-of-the-art on MOT, it ranks 1st in the UA-DETRAC'18 tracking challenge
among online trackers, and 3rd overall.Comment: Accepted at Image and Vision Computing Journa
Latent class analysis variable selection
We propose a method for selecting variables in latent class analysis, which is the most common model-based clustering method for discrete data. The method assesses a variable's usefulness for clustering by comparing two models, given the clustering variables already selected. In one model the variable contributes information about cluster allocation beyond that contained in the already selected variables, and in the other model it does not. A headlong search algorithm is used to explore the model space and select clustering variables. In simulated datasets we found that the method selected the correct clustering variables, and also led to improvements in classification performance and in accuracy of the choice of the number of classes. In two real datasets, our method discovered the same group structure with fewer variables. In a dataset from the International HapMap Project consisting of 639 single nucleotide polymorphisms (SNPs) from 210 members of different groups, our method discovered the same group structure with a much smaller number of SNP
Inference and Evaluation of the Multinomial Mixture Model for Text Clustering
In this article, we investigate the use of a probabilistic model for
unsupervised clustering in text collections. Unsupervised clustering has become
a basic module for many intelligent text processing applications, such as
information retrieval, text classification or information extraction. The model
considered in this contribution consists of a mixture of multinomial
distributions over the word counts, each component corresponding to a different
theme. We present and contrast various estimation procedures, which apply both
in supervised and unsupervised contexts. In supervised learning, this work
suggests a criterion for evaluating the posterior odds of new documents which
is more statistically sound than the "naive Bayes" approach. In an unsupervised
context, we propose measures to set up a systematic evaluation framework and
start with examining the Expectation-Maximization (EM) algorithm as the basic
tool for inference. We discuss the importance of initialization and the
influence of other features such as the smoothing strategy or the size of the
vocabulary, thereby illustrating the difficulties incurred by the high
dimensionality of the parameter space. We also propose a heuristic algorithm
based on iterative EM with vocabulary reduction to solve this problem. Using
the fact that the latent variables can be analytically integrated out, we
finally show that Gibbs sampling algorithm is tractable and compares favorably
to the basic expectation maximization approach
A Strategy analysis for genetic association studies with known inbreeding
Background: Association studies consist in identifying the genetic variants which are related to a specific disease through the use of statistical multiple hypothesis testing or segregation analysis in pedigrees. This type of studies has been very successful in the case of Mendelian monogenic disorders while it has been less successful in identifying genetic variants related to complex diseases where the insurgence depends on the interactions between different genes and the environment. The current technology allows to genotype more than a million of markers and this number has been rapidly increasing in the last years with the imputation based on templates sets and whole genome sequencing. This type of data introduces a great amount of noise in the statistical analysis and usually requires a great number of samples. Current methods seldom take into account gene-gene and gene-environment interactions which are fundamental especially in complex diseases. In this paper we propose to use a non-parametric additive model to detect the genetic variants related to diseases which accounts for interactions of unknown order. Although this is not new to
the current literature, we show that in an isolated population, where the most related subjects share also most of their genetic code, the use of additive models may be improved if the available genealogical tree is taken into account. Specifically, we form a sample of cases and controls with the highest inbreeding by means of the Hungarian method, and estimate the set of genes/environmental variables, associated with the disease, by means of Random Forest.
Results: We have evidence, from statistical theory, simulations and two applications, that we build a suitable
procedure to eliminate stratification between cases and controls and that it also has enough precision in
identifying genetic variants responsible for a disease. This procedure has been successfully used for the betathalassemia, which is a well known Mendelian disease, and also to the common asthma where we have identified
candidate genes that underlie to the susceptibility of the asthma. Some of such candidate genes have been also found related to common asthma in the current literature.
Conclusions: The data analysis approach, based on selecting the most related cases and controls along with the Random Forest model, is a powerful tool for detecting genetic variants associated to a disease in isolated
populations. Moreover, this method provides also a prediction model that has accuracy in estimating the unknown disease status and that can be generally used to build kit tests for a wide class of Mendelian diseases
End-to-end people detection in crowded scenes
Current people detectors operate either by scanning an image in a sliding
window fashion or by classifying a discrete set of proposals. We propose a
model that is based on decoding an image into a set of people detections. Our
system takes an image as input and directly outputs a set of distinct detection
hypotheses. Because we generate predictions jointly, common post-processing
steps such as non-maximum suppression are unnecessary. We use a recurrent LSTM
layer for sequence generation and train our model end-to-end with a new loss
function that operates on sets of detections. We demonstrate the effectiveness
of our approach on the challenging task of detecting people in crowded scenes.Comment: 9 pages, 7 figures. Submitted to NIPS 2015. Supplementary material
video: http://www.youtube.com/watch?v=QeWl0h3kQ2
Online Visual Robot Tracking and Identification using Deep LSTM Networks
Collaborative robots working on a common task are necessary for many
applications. One of the challenges for achieving collaboration in a team of
robots is mutual tracking and identification. We present a novel pipeline for
online visionbased detection, tracking and identification of robots with a
known and identical appearance. Our method runs in realtime on the limited
hardware of the observer robot. Unlike previous works addressing robot tracking
and identification, we use a data-driven approach based on recurrent neural
networks to learn relations between sequential inputs and outputs. We formulate
the data association problem as multiple classification problems. A deep LSTM
network was trained on a simulated dataset and fine-tuned on small set of real
data. Experiments on two challenging datasets, one synthetic and one real,
which include long-term occlusions, show promising results.Comment: IEEE/RSJ International Conference on Intelligent Robots and Systems
(IROS), Vancouver, Canada, 2017. IROS RoboCup Best Paper Awar
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