Jason Dykes

Space, time and visual analytics

Visual analytics aims to combine the strengths of human and electronic data processing. Visualisation, whereby humans and computers cooperate through graphics, is the means through which this is achieved. Seamless and sophisticated synergies are required for analysing spatio-temporal data and solving spatio-temporal problems. In modern society, spatio-temporal analysis is not solely the business of professional analysts. Many citizens need or would be interested in undertaking analysis of information in time and space. Researchers should find approaches to deal with the complexities of the current data and problems and find ways to make analytical tools accessible and usable for the broad community of potential users to support spatio-temporal thinking and contribute to solving a large range of problems.

Exploring spatial data representation with dynamic graphics

Abstract Dynamic mapping capabilities are providing enormous potential for visualizing spatial data. Dynamic maps which exhibit observer-related behaviour are particularly appropriate for exploratory analysis, where multiple, short-term, slightly different, views of a data set, each produced with a specific task or question in mind, are an essential part of the analytical process. This paper and the associated coloured and dynamic illustrations take advantage of World Wide Web (WWW) delivery and the digital medium by using interactive graphics to introduce an approach to dynamic cartography based upon the Tcl/Tk graphical user interface (GUI) builder. Generic ways of programming observer-related behaviour, such as brushing, dynamic re-expression, and dynamic comparison, are outlined and demonstrated to show that specialist dynamic views can be developed rapidly in an open, flexible, and high-level graphic environment. Such an approach provides opportunities to reinforce traditional cartographic and statistical representations of spatial data with dynamic graphics and transient symbolism which give supplementary information about a symbol or statistic on demand. A series of examples from recent work which uses the approach demonstrates ways in which dynamic graphics can be effective in complementing methods of measurement and mapping which are well established in geographic enquiry.

Spatially Ordered Treemaps

Existing treemap layout algorithms suffer to some extent from poor or inconsistent mappings between data order and visual ordering in their representation, reducing their cognitive plausibility. While attempts have been made to quantify this mismatch, and algorithms proposed to minimize inconsistency, solutions provided tend to concentrate on one-dimensional ordering. We propose extensions to the existing squarified layout algorithm that exploit the two-dimensional arrangement of treemap nodes more effectively. Our proposed spatial squarified layout algorithm provides a more consistent arrangement of nodes while maintaining low aspect ratios. It is suitable for the arrangement of data with a geographic component and can be used to create tessellated cartograms for geovisualization. Locational consistency is measured and visualized and a number of layout algorithms are compared. CIELab color space and displacement vector overlays are used to assess and emphasize the spatial layout of treemap nodes. A case study involving locations of tagged photographs in the Flickr database is described.

Visualisation of Origins, Destinations and Flows with OD Maps

Abstract We present a new technique for the visual exploration of origins (O) and destinations (D) arranged in geographic space. Previous attempts to map the flows between origins and destinations have suffered from problems of occlusion usually requiring some form of generalisation, such as aggregation or flow density estimation before they can be visualized. This can lead to loss of detail or the introduction of arbitrary artefacts in the visual representation. Here, we propose mapping OD vectors as cells rather than lines, comparable with the process of constructing OD matrices, but unlike the OD matrix, we preserve the spatial layout of all origin and destination locations by constructing a gridded two-level spatial treemap. The result is a set of spatially ordered small multiples upon which any arbitrary geographic data may be projected. Using a hash grid spatial data structure, we explore the characteristics of the technique through a software prototype that allows interactive query and visualisation of 105-106 simulated and recorded OD vectors. The technique is illustrated using US county to county migration and commuting statistics.

Visualizing the Dynamics of London's Bicycle-Hire Scheme

Abstract Visualizing flows between origins and destinations can be straightforward when dealing with small numbers of journeys or simple geographies. Lines embedded in geographic space have commonly been used in mapping transport flows, especially when geographic patterns are important, as they are when characterizing cities or managing transportation. For larger numbers of flows, however, this approach requires careful design to avoid problems of occlusion, salience bias, and information overload. Driven by the requirements identified by users and managers of the London Bicycle Hire scheme, we present three methods of representation of bicycle-hire use and travel patterns. Flow maps with curved flow symbols are used to show overviews in flow structures. Gridded views of docking-station locations that preserve geographic relationships are used to explore docking-station status over space and time in a graphically efficient manner. Origin–Destination maps that visualize the OD matrix directly while maintai...

Representation and its Relationship with Cartographic Visualization

A research agenda is presented which addresses the current role and potential of map displays. By considering the geospatial data used in visualization, the form and design of maps, the purposes for which map displays are created, the nature of the map user community, and the technology employed to visualize geospatial data, a thorough overview of the nature of cartographic visualization is given. Under the same themes, and sourced in cartographic tradition, cartographic practice and technological opportunities, a series of possible research avenues are highlighted. The important links between representation and the user interface, map user cognition and the geospatial database are stressed.

Virtual environments for student fieldwork using networked components

The topics of virtual environments and information technology are addressed here in the context of fieldwork teaching. A pedagogic rationale is presented that considers the objectives of fieldwork and outlines the potential utility of networked graphical tools in this mode of teaching that is so essential to a range of subjects. The Virtual Field Course project (VFC) is developing software that realises this potential by fulfilling a stated series of objectives. A software architecture and implementation are presented that enable visualization software to communicate with a secure and remote shared library of spatially referenced data to support field-based activity. The software is extremely flexible and uses equipment, data and resources that are affordable and accessible to the higher education community. Two example applications are provided. Each uses the described architecture to visualize geographic information in support of fieldwork. Empirical feedback is provided gained from experience of using ...

Human-Centered Approaches in Geovisualization Design: Investigating Multiple Methods Through a Long-Term Case Study

Working with three domain specialists we investigate human-centered approaches to geovisualization following an ISO13407 taxonomy covering context of use, requirements and early stages of design. Our case study, undertaken over three years, draws attention to repeating trends: that generic approaches fail to elicit adequate requirements for geovis application design; that the use of real data is key to understanding needs and possibilities; that trust and knowledge must be built and developed with collaborators. These processes take time but modified human-centred approaches can be effective. A scenario developed through contextual inquiry but supplemented with domain data and graphics is useful to geovis designers. Wireframe, paper and digital prototypes enable successful communication between specialist and geovis domains when incorporating real and interesting data, prompting exploratory behaviour and eliciting previously unconsidered requirements. Paper prototypes are particularly successful at eliciting suggestions, especially for novel visualization. Enabling specialists to explore their data freely with a digital prototype is as effective as using a structured task protocol and is easier to administer. Autoethnography has potential for framing the design process. We conclude that a common understanding of context of use, domain data and visualization possibilities are essential to successful geovis design and develop as this progresses. HC approaches can make a significant contribution here. However, modified approaches, applied with flexibility, are most promising. We advise early, collaborative engagement with data - through simple, transient visual artefacts supported by data sketches and existing designs - before moving to successively more sophisticated data wireframes and data prototypes.

Using Java to interact with geo—referenced VRML within a virtual field course

Abstract Virtual reality technology is providing earth scientists and cartographers with new, exciting and interactive ways to model the world and real-life phenomena. The Virtual Field Course (VFC) is developing software to enable students to experience fieldwork environments through multimedia, including virtual reality. The VFC aims to exploit the interactive nature of VR to enhance fieldwork teaching and learning. During preliminary development of a spatial interface for a Virtual Field Course geo-referenced multimedia database, a two-dimensional Java interface has been designed to provide information and interaction with three-dimensional VRML terrain models. During this process both the scope and the constraints of geo-referenced VRML have been examined. Recommendations about geo-referencing VRML models, terrain construction and Java interfacing are made and potentially useful areas for future development are identified.

Facilitating Interaction for Geovisualization

Publisher Summary This chapter provides a brief overview of some of the approaches available to support geovisualization. Various tools and techniques have been introduced and contextualized through the personal experience of capitalizing upon the opportunities afforded by technologies that enable to use and develop interactive graphics to prompt thinking. Efficient combination of various ways of instructing computers is identified as a key objective to overcoming impediments to the process of geovisualization and the concept of the “visualization effort” required to chase ideas and support the thought process is emphasized. A number of means of increasing efficiencies, sharing software components, and reusing resources to facilitate interaction are discussed. Scripting is identified as an approach that offers much to fields where application design involves combining existing software functionality in new and unpredictable ways in an iterative process of continual change. Geovisualization is one such application area and flexible high-level environment for instructing computers that offer rapid results and efficiencies and flexibility by drawing upon existing functionality; the opportunity to augment this through integration with lower level languages possess considerable scope for use as instruments for ideation.