1,721,233 research outputs found
Abnormal event detection in video surveillance / Lim Mei Kuan
Get PDFThe recent Boston Marathon bombing and the kidnap of a British boy at Lake Titiwangsa,
have ignited a pressing interest for automated video content analysis to assist the
law enforcement in preventing such events from recurring. Post-mortem investigations
surrounding such cases often found that there were missed opportunities for using technology
to detect the abnormality of the suspects, which lead to those tragedies. Therefore,
this thesis aims to develop computer vision solutions to identify regions or behaviours,
which could lead to unfavourable events, as a cue to direct the attention of security personnel
for a more effective and proactive video surveillance.
The first contribution of this thesis introduces a robust visual tracking algorithm that
is able to locate moving objects in surveillance videos. A great challenge in this domain
is the capability of dealing with complex scenarios of tracking abrupt motion, such
as switching between cameras, which is very common when the number of CCTV to
be monitored is enormous. Conventional sampling-based predictors often assume that
motion is governed by a Gaussian distribution. This assumption holds true for smooth
motion but fails in the case of abrupt motion. Therefore, by considering tracking as an
optimisation problem, the proposed SwATrack algorithm searches for the optimal distribution
of motion model without making prior assumptions, or prior learning of the motion
model. Experimental results have shown that the proposed SwATrack improves the accuracy
of tracking abrupt motion, with an average accuracy of 91.39%, while significantly
reduces the computational overheads, with an average processing time of 63 milliseconds
per frame.
Visual tracking of objects at mass gatherings such as rallies can be daunting due
to the large variations of crowd. Hence, the second contribution proposes an alternative
solution that deals with dense crowd scenes. A new research direction that identifies and
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localises interesting regions by exploiting the motion dynamics of crowd is proposed.
Here, interesting regions refer to abnormalities, where they exhibit high motion dynamics
or irregularities. This assumption alludes to the social behaviours and conventions of
humans in crowded scenes. Therefore, the possibility of abnormal events taking place
is considered likely, when there is high motion dynamics and irregularities. Experiment
results have shown an average accuracy of 78% on the defined dataset.
The third contribution aims to provide an integrated solution to detect multiple events
in different regions-of-interest of a given scene. This is very critical in the real-world
scenarios where multiple events may take place in a scene at the same time. Existing
solutions such as CROMATICA and PRISMATICA are commonly limited to detect single
events, at a particular time. On the contrary, the proposed solution provides flexibility to
deal with different environments, for a broader degree of scene understanding. The key
idea is to conceptually decompose information obtained from a given scene into several
intermediate degrees of abstractions. These low-level descriptions are then integrated
using a basic set of rule-packages, to discriminate the different events. Experimental
results on fives scenarios of abnormal events have shown an average accuracy of 83%
An integrated three-flow approach for front-end service composition / Lim Mei Ting
No full textEnd-User Service Composition (EUSC) aims to enable end-user programmers who are not professional developers, develop applications by composing or aggregating existing web services. Despite the effort, studies have shown that end-user programmers are not able to deal with the technical complexities involved in EUSC. One way to deal with this issue is Front-End Service Composition (FESC), which allows end-user programmers to compose web services at the presentation layer of an application by configuring User Interface (UI) widgets that represent the back-end web services. However, apart from there not being enough studies on FESC, end-user programmers also experience a number of conceptual and usability issues in service composition. Following that, this research proposes an integrated three-flow approach namely application flow, control flow and data flow, to help deal with the current limitations of FESC. The approach generates the Graphical User Interface (GUI) of web services automatically, thus allowing the UI of the application to be developed at the same time the required web services are assembled. The approach allows end-user programmers to explicitly configure the three different types of flows involved in service composition. A proof-of-concept prototype, QuickWSC, that incorporates the three-flow approach was developed. It adopts a side-by-side multiple-view design to support visual configuration of the three flows in an uncluttered yet synchronized manner that adheres to established design guidelines. A user evaluation study which comprised the think-aloud protocol, observation and survey was conducted for data collection purpose where end-user programmers were recruited to evaluate QuickWSC. During the user evaluation study, the end-user programmer was given a brief introduction about the research. Thereafter, a predefined scenario was given to the end-user programmer for a web service composition task. The composition process was recorded on video for data analysis purposes. Framework analysis approach and descriptive statistics were used for qualitative and quantitative data analysis respectively. The results achieved was decently positive. Triangulation was performed during discussion over the results by using the qualitative and quantitative analysed data, and providing a more comprehensive finding of the prototype usability and its features. The evaluation results show that QuickWSC has a high level of usability and it is easy to compose web services by explicitly specifying the three flows, the three-flow configurations integrated into the two views helps in composing application from web services, and that no technical knowledge is required to use QuickWSC. This research has successfully implemented the prototype based on the proposed approach to address a number of conceptual and usability issues in service composition faced by the end-user
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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