Micro Visualizations: Design and Analysis of Visualizations for Small Display Spaces

The topic of this habilitation is the study of very small data visualizations, micro visualizations, in display contexts that can only dedicate minimal rendering space for data representations. For several years, together with my collaborators, I have been studying human perception, interaction, and analysis with micro visualizations in multiple contexts. In this document I bring together three of my research streams related to micro visualizations: data glyphs, where my joint research focused on studying the perception of small-multiple micro visualizations, word-scale visualizations, where my joint research focused on small visualizations embedded in text-documents, and small mobile data visualizations for smartwatches or fitness trackers. I consider these types of small visualizations together under the umbrella term ``micro visualizations.'' Micro visualizations are useful in multiple visualization contexts and I have been working towards a better understanding of the complexities involved in designing and using micro visualizations. Here, I define the term micro visualization, summarize my own and other past research and design guidelines and outline several design spaces for different types of micro visualizations based on some of the work I was involved in since my PhD.Le sujet de cette habilitation est l'étude de très petites visualisations de données, les micro visualisations, dans des contextes d'affichage qui ne peuvent consacrer qu'un espace de rendu minimal aux représentations de données. Depuis plusieurs années, avec mes collaborateurs, j'étudie la perception humaine, l'interaction et l'analyse conduite avec des micro visualisations dans de multiples contextes.Dans ce document, je rassemble trois de mes axes de recherche liés aux micro visualisations~: les glyphes de données, où ma recherche s'est concentrée sur l'étude de la perception de micro visualisations dans un context \textit{small-multiple}, les \textit{word-scale visualizations}, où ma recherche s'est concentrée sur les petites visualisations intégrées dans les documents textuels, et les petites visualisations de données mobiles pour les montres connectées. Je considère ces types de petites visualisations sous le terme générique de ``micro visualisations.'' Les micro visualisations sont utiles dans de multiples contextes de visualisation et j'ai travaillé à une meilleure compréhension de la complexité des conceptions et utilisations des micro visualisations. Je définirai ici le terme de micro visualisation, je résumerai mes propres recherches et celles d'autres chercheurs, ainsi que les directives de conception, et j'esquisserai plusieurs espaces de conception pour différents types de micro visualisations, sur la base de certains des travaux auxquels j'ai participé depuis mon doctorat

Visualisation of Large-Scale Call-Centre Data

The contact centre industry employs 4% of the entire United King-dom and United States’ working population and generates gigabytes of operational data that require analysis, to provide insight and to improve efficiency. This thesis is the result of a collaboration with QPC Limited who provide data collection and analysis products for call centres. They provided a large data-set featuring almost 5 million calls to be analysed. This thesis utilises novel visualisation techniques to create tools for the exploration of the large, complex call centre data-set and to facilitate unique observations into the data.A survey of information visualisation books is presented, provid-ing a thorough background of the field. Following this, a feature-rich application that visualises large call centre data sets using scatterplots that support millions of points is presented. The application utilises both the CPU and GPU acceleration for processing and filtering and is exhibited with millions of call events.This is expanded upon with the use of glyphs to depict agent behaviour in a call centre. A technique is developed to cluster over-lapping glyphs into a single parent glyph dependant on zoom level and a customizable distance metric. This hierarchical glyph repre-sents the mean value of all child agent glyphs, removing overlap and reducing visual clutter. A novel technique for visualising individually tailored glyphs using a Graphics Processing Unit is also presented, and demonstrated rendering over 100,000 glyphs at interactive frame rates. An open-source code example is provided for reproducibility.Finally, a novel interaction and layout method is introduced for improving the scalability of chord diagrams to visualise call transfers. An exploration of sketch-based methods for showing multiple links and direction is made, and a sketch-based brushing technique for filtering is proposed. Feedback from domain experts in the call centre industry is reported for all applications developed

A method for the visualisation of historical multivariate spatial data

The use of spatial technologies and geographical concepts for historical investigation is an area of increasing academic interest. This interest has led to the emergence of the field of Historical Geographic Information Systems (Historical GIS), in which history and geography are inextricably linked in both technology and scholarship. Utilising historical sources requires greater emphasis to be placed on the temporal aspects of the data and often involves the tracking of historical events over time. This temporal focus has challenged the suitability of current visual representations utilised in Historical GIS. This is because the majority of projects rely on conventional geographic visualisation representation designed primarily for emphasising the geographic, not temporal, aspects of the data. This thesis establishes a visualisation method for investigating and analysing the temporal and geographical nature of historical events. In particular, it will focus on addressing the importance of visualising multiple variables and depicting change of these variables over time, with the aid of a Historical GIS and data graphics, for understanding the patterns and relationships between them. The visualisation method enables these temporal and geographic aspects of historical spatial data, along with multivariate capabilities, to be incorporated effectively by extending the spatial dimension of time-series graphs, meaningful classification, and by utilising the capacity to show change and variability in linear spatial objects. This thesis demonstrates the benefits gained from visualising historical, geographic, temporal, and multivariate data concurrently through a Case Study on the history of Melbourne’s cinema venues between 1946 and 1986. The history of cinema operation involves information on 289 cinema venues across a period of great cultural and technological change. Application of the visualisation method was used to address a number of Geographic Questions relating to specifics of cinema venue change by representing chosen venue locations and operation variables (such as seating capacity and ownership) over a specified temporal period. This has enabled data that is usually reserved for written communication to be visually analysed, interpreted, and displayed in a way not previously explored. It has been found that by creating visual access to multivariate and temporal spatial information it is possible to produce new insights into the geographic and temporal patterns and relationships present in historical data

Cognitive Foundations for Visual Analytics

In this report, we provide an overview of scientific/technical literature on information visualization and VA. Topics discussed include an update and overview of the extensive literature search conducted for this study, the nature and purpose of the field, major research thrusts, and scientific foundations. We review methodologies for evaluating and measuring the impact of VA technologies as well as taxonomies that have been proposed for various purposes to support the VA community. A cognitive science perspective underlies each of these discussions

Strategies for image visualisation and browsing

PhDThe exploration of large information spaces has remained a challenging task even though the proliferation of database management systems and the state-of-the art retrieval algorithms is becoming pervasive. Signi cant research attention in the multimedia domain is focused on nding automatic algorithms for organising digital image collections into meaningful structures and providing high-semantic image indices. On the other hand, utilisation of graphical and interactive methods from information visualisation domain, provide promising direction for creating e cient user-oriented systems for image management. Methods such as exploratory browsing and query, as well as intuitive visual overviews of image collection, can assist the users in nding patterns and developing the understanding of structures and content in complex image data-sets. The focus of the thesis is combining the features of automatic data processing algorithms with information visualisation. The rst part of this thesis focuses on the layout method for displaying the collection of images indexed by low-level visual descriptors. The proposed solution generates graphical overview of the data-set as a combination of similarity based visualisation and random layout approach. Second part of the thesis deals with problem of visualisation and exploration for hierarchical organisation of images. Due to the absence of the semantic information, images are considered the only source of high-level information. The content preview and display of hierarchical structure are combined in order to support image retrieval. In addition to this, novel exploration and navigation methods are proposed to enable the user to nd the way through database structure and retrieve the content. On the other hand, semantic information is available in cases where automatic or semi-automatic image classi ers are employed. The automatic annotation of image items provides what is referred to as higher-level information. This type of information is a cornerstone of multi-concept visualisation framework which is developed as a third part of this thesis. This solution enables dynamic generation of user-queries by combining semantic concepts, supported by content overview and information ltering. Comparative analysis and user tests, performed for the evaluation of the proposed solutions, focus on the ways information visualisation a ects the image content exploration and retrieval; how e cient and comfortable are the users when using di erent interaction methods and the ways users seek for information through di erent types of database organisation