Menno-Jan Kraak

Research challenges in geovisualization

1Alan M. MacEachren is Professor and Director of the GeoVISTA Center, Department of Geography, 302 Walker, Penn State University, University Park, PA 16802 USA; e-mail: alan@geog.psu.edu and Menno-Jan Kraak is Professor and Head of Division of Geoinformatics, Cartography and Visualization, ITC, PO Box 6, 7500 AA Enschede; e-mail: kraak@itc.nl This special issue of Cartography and Geographic Information Science presents the results of an international collaboration to delineate a four-part research agenda for geovisualization. Geovisualization integrates approaches from visualization in scientific computing (ViSC), cartography, image analysis, information visualization, exploratory data analysis (EDA), and geographic information systems (GISystems) to provide theory, methods, and tools for visual exploration, analysis, synthesis, and presentation of geospatial data (any data having geospatial referencing). Primary themes addressed here are representation of geospatial information, integration of visual with computational methods of knowledge construction, interface design for geovisualization environments, and cognitive/usability aspects of geovisualization. The International Cartographic Association (ICA) Commission on Visualization and Virtual Environments took the lead in developing this comprehensive research agenda by organizing an international team to address each theme. The teams included both Commission members and others active in geovisualization and related areas. Participants represent a range of disciplines and include representatives from government and the private sector as well as academic researchers. Each team was assisted by an expert from outside geographic information science who provided critical review of white papers prior to completion of final manuscripts. The full set of manuscripts was then submitted to formal peer review. The research agenda development process is detailed in the appendix. In this essay, we provide an overview of the organizational, technological, and scientific context for this research agenda setting effort, emphasizing changes in each that prompted the project at this time. Next, we outline the core issues identified within each of the four agenda themes and summarize challenges identified. Then, challenges that cut across the four themes are delineated. We conclude with recommendations for action.

Geovisual analytics for spatial decision support: Setting the research agenda

This article summarizes the results of the workshop on Visualization, Analytics & Spatial Decision Support, which took place at the GIScience conference in September 2006. The discussions at the workshop and analysis of the state of the art have revealed a need in concerted cross‐disciplinary efforts to achieve substantial progress in supporting space‐related decision making. The size and complexity of real‐life problems together with their ill‐defined nature call for a true synergy between the power of computational techniques and the human capabilities to analyze, envision, reason, and deliberate. Existing methods and tools are yet far from enabling this synergy. Appropriate methods can only appear as a result of a focused research based on the achievements in the fields of geovisualization and information visualization, human‐computer interaction, geographic information science, operations research, data mining and machine learning, decision science, cognitive science, and other disciplines. The name ‘Geovisual Analytics for Spatial Decision Support’ suggested for this new research direction emphasizes the importance of visualization and interactive visual interfaces and the link with the emerging research discipline of Visual Analytics. This article, as well as the whole special issue, is meant to attract the attention of scientists with relevant expertise and interests to the major challenges requiring multidisciplinary efforts and to promote the establishment of a dedicated research community where an appropriate range of competences is combined with an appropriate breadth of thinking.

Exploratory cartographic visualization: advancing the agenda

Abstract An approach to the visualization of georeferenced data is presented. This approach is rooted in cartography and emphasizes the use of visual methods in research and decision making. Several definitions proposed within cartography are considered and the links between “cartographic” visualization and scientific visualization more generally are discussed. From this base, a perspective on visualization is articulated in which attention is directed to the goals for use of maps and related georeferenced displays. We argue that a use-based approach is needed in order to develop information processing environments appropriate to distinct stages of scientific research and decision making. The paper concludes by proposing a set of research problems that are prompted by taking a use-based approach to visualization, and then outlining the selection and context of the papers in this special issue.

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.

Web cartography : developments and prospects

The World Wide Web has rapidly become a widespread means for the publication of geospatial data. It has earned this popularity since it is virtually platform independent can reach many users at minimal cost and is easy to update. More importantly, the web meets the increasing demand for customized geospatial data products. However, the visual dissemination of spatial data on the web creates special requirements for map design, and introduces new capabilities and pitfalls for interactive map applications.Web maps are first put into a broad context and specific characteristics of these maps are then examined from a user perspective. The various functions of maps on the Web are discussed in the context of the technical background and fundamental user questions such as what can be done with existing data. Web cartography also provides insight into the particularities of multi-dimensional web maps. Typical characteristics are explained clearly from the perspectives of static viewing and dynamic viewing. For each category, design considerations, based on cartographic principles, are discussed. Topics addressed include map contents, map physics and the map environment. Technical terms are explained where necessary. For several time-sensitive topics such as traffic, weather and tourism, the status and future of web maps are discussed. Atlases and national mapping agencies are also covered.The website http:://kartoweb.itc.nl/webcartography/webbook accompanies the book. It provides a dynamic environment for demonstrating many of the principles set out in the text and includes access to a basic course on Web cartography. The book and website provide a text for students and professionals in the fields of cartography and GIS. The series of chapters are written by different people but worked together into a single text.

Evaluating the usability of visualization methods in an exploratory geovisualization environment

The use of new representation forms and interactive means to visualize geospatial data requires an understanding of the impact of the visual tools used for data exploration and knowledge construction. Use and usability assessment of implemented methods and tools is an important part of our efforts to build this understanding. Based on an approach to combine visual and computational methods for knowledge discovery in large geospatial data, an integrated visualization‐geocomputation environment has been developed based on the Self‐Organizing Map (SOM), the map and the parallel coordinate plot. This environment allows patterns and attribute relationships to be explored. A use and usability assessment is conducted to evaluate the ability of each of these visual representations to meet user performance and satisfaction goals. In the test, different representations are compared while exploring a socio‐demographic dataset.

The role of the map in a Web-GIS environment

Abstract.The World Wide Web has changed the perspective on the role that maps can play. Their traditional function remains, e.g. to represent an abstraction of a selected part of reality to offer insight into geospatial patterns and relations. Additionally the map can be an important part of a search engine, especially in the context of geospatial data infrastructure. Maps can also function as an interface to other geographic and non-geographic information on the Web. The question ‘What are the implications of this expanding role of maps for a WebGIS environment?’ is addressed in this paper.

Visual exploration of eye movement data using the space-time-cube

Eye movement recordings produce large quantities of spatiotemporal data, and are more and more frequently used as an aid to gain further insight into human thinking in usability studies in GIScience domain among others. After reviewing some common visualization methods for eye movement data, the limitations of these methods are discussed. This paper proposes an approach that enables the use of the Space-Time-Cube (STC) for representation of eye movement recordings. Via interactive functions in the STC, spatio-temporal patterns in eye movement data could be analyzed. A case study is presented according to proposed solutions for eye movement data analysis. Finally, the advantages and limitations of using the STC to visually analyze eye movement recordings are summarized and discussed.

Interactive and visual fuzzy classification of remotely sensed imagery for exploration of uncertainty

In this study, we propose, describe, and demonstrate a new geovisualization tool to demonstrate the use of exploratory and interactive visualization techniques for a visual fuzzy classification of remotely sensed imagery. The proposed tool uses dynamically linked views, consisting of an image display, a parallel coordinate plot, a 3D feature space plot, and a classified map with an uncertainty map. It allows a geoscientist to interact with the parameters of a fuzzy classification algorithm by visually adjusting fuzzy membership functions and fuzzy transition zones of land-cover classes. The purpose of this tool is to improve insight into fuzzy classification of remotely sensed imagery and related uncertainty. We tested our tool with a visual fuzzy land-cover classification of a Landsat 7 ETM+ image of an area in southern France characterized by objects with indeterminate boundaries. Good results were obtained with the visual classifier. Additionally, a focus-group user test of the tool showed that insight into a fuzzy classification algorithm and classification uncertainty improved considerably.

A usability framework for the design and evaluation of an exploratory geovisualization environment

The exploration of large geospatial data for finding patterns and understanding underlying processes is one of the challenges in geovisualization research. New methods are needed for effective extraction of patterns and appropriate visualization tools are necessary to support knowledge construction throughout the exploration process. Based on an approach to combine visual and computational methods, a visualization environment has been developed to support visual data mining and knowledge discovery tasks. This environment integrates non-geographic information spaces with maps and other graphics that allow users to explore patterns and attribute relationships. The development of the tool intends to facilitate knowledge construction using a number of steps that underline data mining and knowledge discovery methodology. In order to investigate the effectiveness of the design concept, an empirical usability testing is planed to assess the tools ability to meet user performance and satisfaction. In this test, different options of map-based and interactive visualizations of the output of a self-organizing map (SOM) are used to explore a socio-demographic dataset. The study emphasizes the knowledge discovery process based on exploratory tasks and visualization operations. This paper describes the usability framework used to guide the design, and examines key aspects of the evaluation of such visual-computational environment.