The State of the Art in Cartograms

Cartograms combine statistical and geographical information in thematic maps, where areas of geographical regions (e.g., countries, states) are scaled in proportion to some statistic (e.g., population, income). Cartograms make it possible to gain insight into patterns and trends in the world around us and have been very popular visualizations for geo-referenced data for over a century. This work surveys cartogram research in visualization, cartography and geometry, covering a broad spectrum of different cartogram types: from the traditional rectangular and table cartograms, to Dorling and diffusion cartograms. A particular focus is the study of the major cartogram dimensions: statistical accuracy, geographical accuracy, and topological accuracy. We review the history of cartograms, describe the algorithms for generating them, and consider task taxonomies. We also review quantitative and qualitative evaluations, and we use these to arrive at design guidelines and research challenges

Identifying approaches to usability evaluation

Maps are ubiquitous, and created by people of all skill levels. However, many users still struggle to effectively interpret spatial information. Such users have been defined as 'functionally map illiterate' (Clarke 2003). This inability, or perhaps, more accurately, disability, to interpret spatial information can lead to negative experiences. This can be of great concern when these users need to undertake navigational tasks such as wayfinding. As a result, map users may experience anything ranging from unnecessary anxiety to sometimes tragic consequences, due to them being geographically disoriented or completely unaware of their location. To improve the map reading experience for inefficient map readers, it is argued that maps need to be created that allow them to interpret spatial information more easily and effectively. Various methods have been used to evaluate maps for their potential to correctly convey spatial information to specific user groups. It is therefore necessary to determine which methods are the most applicable for evaluating maps created for functionally map illiterate individuals. We note that there are certain problems related to all usability testing situations. Here, we believe that familiarity of landscape needs to be eliminated in order for testing to be effective. This paper reports on early findings to identify possible approaches for evaluating this type of map for this user group