Multi-resolution visualization (MRV) systems are widely used for handling large amounts of information. These systems look different but they share many common features. The visualization research community lacks a general framework that summarizes the common features among the wide variety of MRV systems in order to help in MRV system design, analysis, and enhancement. This dissertation proposes such a general framework. This framework is based on the definition that a MRV system is a visualization system that visually represents perceptions in different levels of detail and allows users to interactively navigate among the representations. The visual representations of a perception are called a view. The framework is composed of two essential components: view simulation and interactive visualization. View simulation means that an MRV system simulates views of non-existing perceptions through simplification on the data structure or the graphics generation process. This is needed when the perceptions provided to the MRV system are not at the user's desired level of detail. The framework identifies classes of view simulation approaches and describes them in terms of simplification operators and operands (spaces). The simplification operators are further divided into four categories, namely sampling operators, aggregation operators, approximation operators, and generalization operators. Techniques in these categories are listed and illustrated via examples. The simplification operands (spaces) are also further divided into categories, namely data space and visualization space. How different simplification operators are applied to these spaces is also illustrated using examples. Interactive visualization means that an MRV system visually presents the views to users and allows users to interactively navigate among different views or within one view. Three types of MRV interface, namely the zoomable interface, the overview + context interface, and the focus + detail interface, are presented with examples. Common interaction tools used in MRV systems, such as zooming and panning, selection, distortion, overlap reduction, previewing, and dynamic simplification are also presented. A large amount of existing MRV systems are used as examples in this dissertation, including several MRV systems developed by the author based on the general framework. In addition, a case study that analyzes and suggests possible improvements for an existing MRV system is described. These examples and the case study reveal that the framework covers the common features of a wide variety of existing MRV systems, and helps users analyze and improve existing MRV systems as well as design new MRV systems.

Geo-based Information Visualizations (GIV) allow people to analyze data points based on their related geographic locations. This approach is usually adopted where a large scale geo-referenced dataset is present and users are trying to find a way to examine hidden patterns within this data. One of the emerging trends in GIV is to visualize social media data to show how information flows between users of popular social networking sites. Due to its public nature and the large number of users, most of the visualizations in this area rely on conversational data from Twitter (Twitter.com). In this thesis, we design and implement a web-based interactive GIV system, AcademiaMap-GIV, to visualize online conversations among scholars on Twitter. A formal exploratory user study was also conducted on the target users. The study results demonstrated that most of the study respondents found the features of AcademiaMap-GIV effective in regards to visualizing information of their interests.

This work presents our research into visualization for digital repository search interfaces, motivated by the prevalence of existing hierarchical data structures and the general lack of contextualization present in existing systems. We develop the ResultMap concept, a treemap-based visualization that we have applied to keyword search engine and faceted classification data environments, and present the results of their empirical evaluation, which show limited objective and subjective benefits for some users and no detrimental effects in any cases. We organize this work as follows: Chapter 1 provides an introduction to our problem area, motivates our general approach of leveraging hierarchical structure (via ResultMaps) for context, and proposes a thesis statement and corresponding research questions. Chapter 2 discusses related work, and includes a survey and design characterization of faceted navigation tools. Chapter 3 defines the key visual and interactive features of the ResultMap concept and justifies their basic design. Chapter 4 presents our implementation and evaluation of ResultMaps applied to digital library search engine result pages (SERPs). Chapter 5 consists of two major portions: a presentation of formal data and query models for faceted environments, and our implementation and evaluation of ResultMaps in a faceted UI context. In Chapter 6 we conclude--based on our results from Chapter 4 and Chapter 5--with a set of principles for designing both visual search interfaces themselves and designing their evaluation. We finish with suggestions for future research in this area.

[Truncated abstract] Many databases in scientific and business applications have grown exponentially in size in recent years. Accessing and using databases is no longer a specialized activity as more and more ordinary users without any specialized knowledge are trying to gain information from databases. Both expert and ordinary users face significant challenges in understanding the information stored in databases. The databases are so large in most cases that it is impossible to gain useful information by inspecting data tables, which are the most common form of storing data in relational databases. Visualization has emerged as one of the most important techniques for exploring data stored in large databases. Appropriate visualization techniques can reveal trends, correlations and associations in data that are very difficult to understand from a textual representation of the data. This thesis presents several new frameworks for data visualization and visual data mining. The first technique, VisEx, is useful for visual exploration of large multi-attribute datasets and especially for exploring the correlations among the attributes in such datasets. Most previous visualization techniques can display correlations among two or three attributes at a time without excessive screen clutter. ... Although many algorithms for mining association rules have been researched extensively, they do not incorporate users in the process and most of them generate a large number of association rules. It is quite often difficult for the user to analyze a large number of rules to identify a small subset of rules that is of importance to the user. In this thesis I present a framework for the user to interactively mine association rules visually. Another challenging task in data mining is to understand the correlations among the mined association rules. It is often difficult to identify a relevant subset of association rules from a large number of mined rules. A further contribution of this thesis is a simple framework in the VisAR system that allows the user to explore a large number of association rules visually. A variety of businesses have adopted new technologies for storing large amounts of data. Analysis of historical data quite often offers new insights into business processes that may increase productivity and profit. On-line analytical processing (OLAP) has become a powerful tool for business analysts to explore historical data. Effective visualization techniques are very important for supporting OLAP technology. A new technique for the visual exploration of OLAP data cubes is also presented in this thesis.

Today e-commerce retailers use large warehouses to store goods before they are sold and shipped. One of the main performance issues for Apotea AB, an online pharmacy based in Sweden, is that the staffers who walk around in the warehouse often are delayed in queues or clusters, usually as a result of missing items or difficulties finding items. This paper describes how, based on sparse data, a map-based interactive visualization was created to aid staffers in their task of evaluating how so called pick lists perform. The visualization was evaluated using UMUX-LITE [20] and a grounded model of NOvice’s information VIsualization Sensemaking (NOVIS-model) [17]. Results showed an overall successful design. The main affordance of the visualization was that it showed warehouse performance over time when animation speed was set to maximum, this was enabled by sliders and buttons. The main limitations were found to be a lack of intermediary level of visualization (e.g. heat map overview of an hour) in the visualization and that there was no higher level of data, e.g. incident data, which could be visualized. These limitations represent the core of what this paper identifies as future work.

published_or_final_version / Industrial and Manufacturing Systems Engineering / Master / Master of Philosophy

Government agencies and corporations are growing increasingly reliant on networks for day-to-day operations including communication, data processing, and data storage. As a result, these networks are in a constant state of growth. These burgeoning networks cause the number of network security events requiring investigation to grow exceptionally, creating new problems for network security analysts. The increasing number of attacks propagated against high-value networks only increases the gravity. Therefore, security analysts need assistance to be able to continue to monitor network events at an acceptable rate. Network analysts rely on many different systems and tools to properly secure a network. One line of defense is an intrusion detection system or IDS. Intrusion detection systems monitor networks for suspicious activity and then print alerts to a log file. An important part of effective intrusion detection is finding relationships between network events, which allows for detection of network anomalies. However, network analysts typically monitor these logs in a sparsely formatted view, which simply isn’t effective for large networks. Therefore, a Visual Intrusion Detection System or VIDS is an interesting solution to aid network security analysts in properly securing the networks. The visualization tool takes a log file and represents the alerts on a three-dimensional graph. Previous research shows that humans have an innate ability to match patterns based on visual cues, which we hope will allow network analysts to match patterns between alerts and identify anomalies. In addition, the tool will leverage the user’s intuition and experience to aid intrusion detection by allowing them to manipulate the view of the data. The objective of this thesis is to quantify and measure the effectiveness of this Visual Intrusion Detection System built as an extension to the SNORT open source IDS. The purpose of the visualization is to give network security analysts an alternative view from what traditional network security software provides. This thesis will also explore other features that can be built into a Visual Intrusion Detection System to improve its functionality. / Department of Computer Science

Um sensor ou biossensor é um dispositivo analítico que tem por objetivo principal a identificação de substâncias e suas concentrações. O emprego efetivo dos sensores permite resolver diversos problemas em várias áreas como química, biologia, medicina, farmacologia, ciências ambientais, entre outras. Dentre desses problemas podemos ressaltar dois: o diagnóstico de doenças e a substituição de seres humanos por línguas eletrônicas para evitar as análises subjetivas. O primeiro problema é resolvido pela identificação de molécula única mas apresenta problemas relacionados a grande quantidade de dados gerados pelos sensores Surface Enhanced Raman Spectroscopy (SERS). Já o segundo problema envolve a recalibração de sensores de espectroscopia de impedância para que possam ser substituídos em línguas eletrônicas quando apresentem deficiências. Em ambos casos foram desenvolvidas abordagens que empregaram técnicas de visualização de informação e permitem uma exploração eficiente da grande quantidade de dados produzidos. A primeira abordagem conseguiu melhorar o tempo de execução do processo de detecção de molécula única em contrapartida a análise manual atualmente empregada além de reduzir o número de falsos positivos. A segunda abordagem, a troca de sensores em línguas eletrônicas, mostrou resultados satisfatórios. O uso da definição do circuito eletrônico equivalente de Taylor em combinação com Generalized Procrustes Analysis (GPA) permitiu de forma adequada a troca de sensores por conseguir transformar a resposta de um sensor na resposta do outro, característica que no futuro poderá ser usada para conseguir produzir sistemas mais reprodutíveis e confiáveis / A sensor or biosensor is an analytical device that aims to identify substances and their concentrations. The efficient employment of sensors allows the solution of many problems in several fields such as chemistry, biology, medicine, pharmacology, environmental sciences, among others. Two problems were the main focus of this master\'s thesis: the diagnosis of diseases and the replacement of human beings by electronic tongues to avoid subjective analysis. The first problem is solved using single molecule detection but presents problems related to the large amount of data generated by sensors Surface Enhanced Raman Spectroscopy (SERS). The second one involves the recalibration of impedance spectroscopy sensors in electronic tongues for them to be replaced when one of them presents defficiencies. We have developed two different approaches to handle these problems, both of them involve information visualization methods making the exploration of large amounts of data more efficiently. The first approach improved the execution time of the single molecule detection process compared to the manual analysis. The number of spectra classified as false positives was also reduced. The second approach, which is a candidate solution to the replacement of sensors in an electronic tongue, employs the definition of the equivalent circuit of Taylor along with Generalized Procrustes Analysis (GPA) to achieve the desired goal. This leads to the recalibration of one sensor into the response of another one, presenting good results. In the future, this could be potentially used to produce more reliable and reproducible systems

Devido ao crescimento acelerado da quantidade de dados disponíveis para análise hoje, é comum lidar com grandes conjuntos de dados, por vezes complexos demais para serem interpretados na sua forma bruta. Por isso, as técnicas de Visualização de Informação têm o objetivo de facilitar para o ser humano a tarefa de análise e interação dos dados por meio da sua abstração em forma gráfica. Justificado pela necessidade de dar autonomia ao usuário final na criação de visualizações, este trabalho pretende delinear a importância da participação do usuário na criação e suporte à abstração da informação em forma gráfica. Para isso, foi desenvolvido o InterVis um sistema para criação interativa de visualizações de informação a partir de dados dinâmicos, que visa a permitir que o usuário final possa gerar e editar visualizações de acordo com a sua necessidade, independentemente da natureza da informação que deve ser analisada. O sistema foi testado utilizando o questionário USE a fim de verificar se a criação interativa de visualizações de informação, sem programação, aliada ao conhecimento do usuário sobre o domínio da aplicação, é mais eficiente da perspectiva da usabilidade sem perda significativa de flexibilidade. Os testes envolveram a execução de tarefas por indivíduos de um grupo de usuários. Todos os usuários conseguiram realizar todas as tarefas de criação e exploração em tempo hábil e avaliaram positivamente o sistema, além de terem sugerido diversas melhorias e novas funcionalidades. É possível concluir que o InterVis atualmente já atende às expectativas iniciais do trabalho, ainda que haja pontos a serem aprimorados em trabalhos futuros / Because of the growing amount of data available for analysis today, it is common to deal with large data sets, often too complex to be interpreted in their brute form. That is why Information Visualization techniques exist, to facilitate the analysis and interaction with data by humans through graphical abstractions. Motivated by the need to allow end users the autonomy to generate and edit visualizations, this work aims to underscore the importance of end user participation in the creation and support of these graphical abstractions of data. For this purpose, it was developed a system for interactive creation of Information Visualizations based on dynamic data, which aims to allow the final user to generate e edit visualizations according to their need and independently of the nature of the information that should be analyzed. This system was tested using the USE questionnaire, to verify whether this interactive creation of Information Visualizations, without programming, allied to the user knowledge of each applications domain, will be more efficient from the perspective of usability without significant loss of flexibility, as expected. The tests were compound of the tasks execution by individuals of a users group. All the users were able to conclude all tasks of creation and exploration in due time and evaluated positively the system, besides they have been suggested diverse improvement and new functionalities. It is possible to conclude that InterVis already fulfills the initial expectations of this work, although there are still points to be refined in future work

University of Macau / Faculty of Science and Technology. / Department of Computer and Information Science