1,420 research outputs found
Quality of Information in Mobile Crowdsensing: Survey and Research Challenges
Smartphones have become the most pervasive devices in people's lives, and are
clearly transforming the way we live and perceive technology. Today's
smartphones benefit from almost ubiquitous Internet connectivity and come
equipped with a plethora of inexpensive yet powerful embedded sensors, such as
accelerometer, gyroscope, microphone, and camera. This unique combination has
enabled revolutionary applications based on the mobile crowdsensing paradigm,
such as real-time road traffic monitoring, air and noise pollution, crime
control, and wildlife monitoring, just to name a few. Differently from prior
sensing paradigms, humans are now the primary actors of the sensing process,
since they become fundamental in retrieving reliable and up-to-date information
about the event being monitored. As humans may behave unreliably or
maliciously, assessing and guaranteeing Quality of Information (QoI) becomes
more important than ever. In this paper, we provide a new framework for
defining and enforcing the QoI in mobile crowdsensing, and analyze in depth the
current state-of-the-art on the topic. We also outline novel research
challenges, along with possible directions of future work.Comment: To appear in ACM Transactions on Sensor Networks (TOSN
Unsupervised routine discovery in egocentric photo-streams
The routine of a person is defined by the occurrence of activities throughout
different days, and can directly affect the person's health. In this work, we
address the recognition of routine related days. To do so, we rely on
egocentric images, which are recorded by a wearable camera and allow to monitor
the life of the user from a first-person view perspective. We propose an
unsupervised model that identifies routine related days, following an outlier
detection approach. We test the proposed framework over a total of 72 days in
the form of photo-streams covering around 2 weeks of the life of 5 different
camera wearers. Our model achieves an average of 76% Accuracy and 68% Weighted
F-Score for all the users. Thus, we show that our framework is able to
recognise routine related days and opens the door to the understanding of the
behaviour of people
Future Person Localization in First-Person Videos
We present a new task that predicts future locations of people observed in
first-person videos. Consider a first-person video stream continuously recorded
by a wearable camera. Given a short clip of a person that is extracted from the
complete stream, we aim to predict that person's location in future frames. To
facilitate this future person localization ability, we make the following three
key observations: a) First-person videos typically involve significant
ego-motion which greatly affects the location of the target person in future
frames; b) Scales of the target person act as a salient cue to estimate a
perspective effect in first-person videos; c) First-person videos often capture
people up-close, making it easier to leverage target poses (e.g., where they
look) for predicting their future locations. We incorporate these three
observations into a prediction framework with a multi-stream
convolution-deconvolution architecture. Experimental results reveal our method
to be effective on our new dataset as well as on a public social interaction
dataset.Comment: Accepted to CVPR 201
Causal Rule Learning: Enhancing the Understanding of Heterogeneous Treatment Effect via Weighted Causal Rules
Interpretability is a key concern in estimating heterogeneous treatment
effects using machine learning methods, especially for healthcare applications
where high-stake decisions are often made. Inspired by the Predictive,
Descriptive, Relevant framework of interpretability, we propose causal rule
learning which finds a refined set of causal rules characterizing potential
subgroups to estimate and enhance our understanding of heterogeneous treatment
effects. Causal rule learning involves three phases: rule discovery, rule
selection, and rule analysis. In the rule discovery phase, we utilize a causal
forest to generate a pool of causal rules with corresponding subgroup average
treatment effects. The selection phase then employs a D-learning method to
select a subset of these rules to deconstruct individual-level treatment
effects as a linear combination of the subgroup-level effects. This helps to
answer an ignored question by previous literature: what if an individual
simultaneously belongs to multiple groups with different average treatment
effects? The rule analysis phase outlines a detailed procedure to further
analyze each rule in the subset from multiple perspectives, revealing the most
promising rules for further validation. The rules themselves, their
corresponding subgroup treatment effects, and their weights in the linear
combination give us more insights into heterogeneous treatment effects.
Simulation and real-world data analysis demonstrate the superior performance of
causal rule learning on the interpretable estimation of heterogeneous treatment
effect when the ground truth is complex and the sample size is sufficient
PRSim: Sublinear Time SimRank Computation on Large Power-Law Graphs
{\it SimRank} is a classic measure of the similarities of nodes in a graph.
Given a node in graph , a {\em single-source SimRank query}
returns the SimRank similarities between node and each node . This type of queries has numerous applications in web search and social
networks analysis, such as link prediction, web mining, and spam detection.
Existing methods for single-source SimRank queries, however, incur query cost
at least linear to the number of nodes , which renders them inapplicable for
real-time and interactive analysis.
{ This paper proposes \prsim, an algorithm that exploits the structure of
graphs to efficiently answer single-source SimRank queries. \prsim uses an
index of size , where is the number of edges in the graph, and
guarantees a query time that depends on the {\em reverse PageRank} distribution
of the input graph. In particular, we prove that \prsim runs in sub-linear time
if the degree distribution of the input graph follows the power-law
distribution, a property possessed by many real-world graphs. Based on the
theoretical analysis, we show that the empirical query time of all existing
SimRank algorithms also depends on the reverse PageRank distribution of the
graph.} Finally, we present the first experimental study that evaluates the
absolute errors of various SimRank algorithms on large graphs, and we show that
\prsim outperforms the state of the art in terms of query time, accuracy, index
size, and scalability.Comment: ACM SIGMOD 201
Dynamic Switching State Systems for Visual Tracking
This work addresses the problem of how to capture the dynamics of maneuvering objects for visual tracking. Towards this end, the perspective of recursive Bayesian filters and the perspective of deep learning approaches for state estimation are considered and their functional viewpoints are brought together
Towards robots reasoning about group behavior of museum visitors: leader detection and group tracking
The final publication is available at IOS Press through http://dx.doi.org/10.3233/AIS-170467Peer ReviewedPostprint (author's final draft
Dynamic Switching State Systems for Visual Tracking
This work addresses the problem of how to capture the dynamics of maneuvering objects for visual tracking. Towards this end, the perspective of recursive Bayesian filters and the perspective of deep learning approaches for state estimation are considered and their functional viewpoints are brought together
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