1,157 research outputs found
Visualizing the Motion Flow of Crowds
In modern cities, massive population causes problems, like congestion, accident, violence and crime everywhere. Video surveillance system such as closed-circuit television cameras is widely used by security guards to monitor human behaviors and activities to manage, direct, or protect people. With the quantity and prolonged duration of the recorded videos, it requires a huge amount of human resources to examine these video recordings and keep track of activities and events. In recent years, new techniques in computer vision field reduce the barrier of entry, allowing developers to experiment more with intelligent surveillance video system. Different from previous research, this dissertation does not address any algorithm design concerns related to object detection or object tracking. This study will put efforts on the technological side and executing methodologies in data visualization to find the model of detecting anomalies. It would like to provide an understanding of how to detect the behavior of the pedestrians in the video and find out anomalies or abnormal cases by using techniques of data visualization
Web Tracking: Mechanisms, Implications, and Defenses
This articles surveys the existing literature on the methods currently used
by web services to track the user online as well as their purposes,
implications, and possible user's defenses. A significant majority of reviewed
articles and web resources are from years 2012-2014. Privacy seems to be the
Achilles' heel of today's web. Web services make continuous efforts to obtain
as much information as they can about the things we search, the sites we visit,
the people with who we contact, and the products we buy. Tracking is usually
performed for commercial purposes. We present 5 main groups of methods used for
user tracking, which are based on sessions, client storage, client cache,
fingerprinting, or yet other approaches. A special focus is placed on
mechanisms that use web caches, operational caches, and fingerprinting, as they
are usually very rich in terms of using various creative methodologies. We also
show how the users can be identified on the web and associated with their real
names, e-mail addresses, phone numbers, or even street addresses. We show why
tracking is being used and its possible implications for the users (price
discrimination, assessing financial credibility, determining insurance
coverage, government surveillance, and identity theft). For each of the
tracking methods, we present possible defenses. Apart from describing the
methods and tools used for keeping the personal data away from being tracked,
we also present several tools that were used for research purposes - their main
goal is to discover how and by which entity the users are being tracked on
their desktop computers or smartphones, provide this information to the users,
and visualize it in an accessible and easy to follow way. Finally, we present
the currently proposed future approaches to track the user and show that they
can potentially pose significant threats to the users' privacy.Comment: 29 pages, 212 reference
Compact Video Streaming & Background Extraction using Pyramidal Optical flow Reduction.
The increasing demand of the cameras for surveillance systems not only requires the large storage devices but also requires the reduction in the time to browse the whole video. Â The major problem in current scenario is use of the surveillance cameras in which they provide unedited raw data. Video browsing and retrieval are inconvenient due to inherent spatio-temp oral redundancies, where some time intervals may have no activity, or have activities that occur in a small image region. To meet such requirements video summarization is the only solution. Hence in our proposed work video summarization algorithm based on pyramidal reduction for surveillance videos is accomplished. Surveillances video summarization is not only related to reduction of size of the video but also to track the important objects in the video by maintaining the chronology
Bayesian nonparametric multilevel modelling and applications
Our research aims at contributing to the multilevel modeling in data analytics. We address the task of multilevel clustering, multilevel regression, and classification. We provide state of the art solution for the critical problem
Anchorage: Visual Analysis of Satisfaction in Customer Service Videos via Anchor Events
Delivering customer services through video communications has brought new
opportunities to analyze customer satisfaction for quality management. However,
due to the lack of reliable self-reported responses, service providers are
troubled by the inadequate estimation of customer services and the tedious
investigation into multimodal video recordings. We introduce Anchorage, a
visual analytics system to evaluate customer satisfaction by summarizing
multimodal behavioral features in customer service videos and revealing
abnormal operations in the service process. We leverage the semantically
meaningful operations to introduce structured event understanding into videos
which help service providers quickly navigate to events of their interest.
Anchorage supports a comprehensive evaluation of customer satisfaction from the
service and operation levels and efficient analysis of customer behavioral
dynamics via multifaceted visualization views. We extensively evaluate
Anchorage through a case study and a carefully-designed user study. The results
demonstrate its effectiveness and usability in assessing customer satisfaction
using customer service videos. We found that introducing event contexts in
assessing customer satisfaction can enhance its performance without
compromising annotation precision. Our approach can be adapted in situations
where unlabelled and unstructured videos are collected along with sequential
records.Comment: 13 pages. A preprint version of a publication at IEEE Transactions on
Visualization and Computer Graphics (TVCG), 202
A comprehensive survey of multi-view video summarization
[EN] There has been an exponential growth in the amount of visual data on a daily basis acquired from single or multi-view surveillance camera networks. This massive amount of data requires efficient mechanisms such as video summarization to ensure that only significant data are reported and the redundancy is reduced. Multi-view video summarization (MVS) is a less redundant and more concise way of providing information from the video content of all the cameras in the form of either keyframes or video segments. This paper presents an overview of the existing strategies proposed for MVS, including their advantages and drawbacks. Our survey covers the genericsteps in MVS, such as the pre-processing of video data, feature extraction, and post-processing followed by summary generation. We also describe the datasets that are available for the evaluation of MVS. Finally, we examine the major current issues related to MVS and put forward the recommendations for future research(1). (C) 2020 Elsevier Ltd. All rights reserved.This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. 2019R1A2B5B01070067)Hussain, T.; Muhammad, K.; Ding, W.; Lloret, J.; Baik, SW.; De Albuquerque, VHC. (2021). A comprehensive survey of multi-view video summarization. Pattern Recognition. 109:1-15. https://doi.org/10.1016/j.patcog.2020.10756711510
State Space Approaches for Modeling Activities in Video Streams
The objective is to discern events and behavior in activities using video sequences, which conform to common human experience. It has several applications such as recognition, temporal segmentation, video indexing and anomaly detection. Activity modeling offers compelling challenges to computational vision systems at several levels ranging from low-level vision tasks for detection and segmentation to high-level models for extracting perceptually salient information. With a focus on the latter, the following approaches are presented: event detection in discrete state space, epitomic representation in continuous state space, temporal segmentation using mixed state models, key frame detection using antieigenvalues and spatio-temporal activity volumes.
Significant changes in motion properties are said to be events. We present an event probability sequence representation in which the probability of event occurrence is computed using stable changes at the state level of the discrete state hidden Markov model that generates the observed trajectories. Reliance on a trained model however, can be a limitation. A data-driven antieigenvalue-based approach is proposed for detecting changes. Antieigenvalues are sensitive to turnings whereas eigenvalues capture directions of maximum variance in the data. In both these approaches, events are assumed to be instantaneous quantities. This is relaxed using an epitomic representation in continuous state space.
Video sequences are segmented using a sliding window within which the dynamics of each object is assumed to be linear. The system matrix, initial state value and the input signal statistics are said to form an epitome. The system matrices are decomposed using the Iwasawa matrix decomposition to isolate the effect of rotation, scaling and projection of the state vector. It is used to compute physically meaningful distances between epitomes. Epitomes reveal dominant primitives of activities that have an abstracted interpretation. A mixed state approach for activities is presented in which higher-level primitives of behavior is encoded in the discrete state component and observed dynamics in the continuous state component. The effectiveness of mixed state models is demonstrated using temporal segmentation. In addition to motion trajectories, the volume carved out in an xyt cube by a moving object is characterized using Morse functions
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Cybersecurity of Online Proctoring Systems
The online proctored examinations are adopted exceedingly in all forms of academic education and professional training. AI with Machine Learning technology take the leading role in supporting authentication, authorization, and operational control of proctored online examination. The paper discusses how administrative, physical, and technical controls can help mitigate related cybersecurity vulnerabilities of online proctoring systems (OPS). The paper considers two classes of OPS: fully automated AI-enabled systems and hybrid systems (automated AI-enabled with an expert live proctor in control). Based on the review of 20 online proctoring systems, the paper discusses methods and techniques of multi-factor authentication and authorizations, including the use of challenge-response, biometrics (face and voice recognition), and blockchain technology. The discussion of operational controls includes the use of lockdown browsers, webcam detection of behavioral signs of fraud, endpoint security, VPN and VM, screen-sharing and keyboard listening programs, technical controls to mitigate the absence of spatial (physical area) controls, compliance with regulations (GDPR), etc. Other topics discussed include confidentiality of the exam content, logging of control data, video and sound recording for auditing, limitations of endpoint-based security protection and detection techniques of behavior-based cheating and the effect of new intrusive technology on students’ privacy. In conclusion, the paper lists advanced features of online proctoring systems
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