Mapping: optimising data visualisation

Maps provide excellent means for describing similarities and differences across specific objects. Maps are a way of translating or converting spatial data - “cartographic visualisation can be claimed to solve many of the fundamental problems identified in studying spatial social distributions” (Dorling 1991). While statistical methods are used to explore patterns and relationships in the data, maps illustrate and support the analysis of spatial data in an easily comprehensible style. As a combination of abstraction and representation, cartography is an incomparable method of a data-handling and data-communicating. The interaction between maps and statistical texts (graphs and charts) is vital to the understanding of scientific phenomena (Cockerill 2003).

Many cartographic technologies are now available, from geographic information systems (GIS), which offer a broad range of analytical functions and integrate map components, to high-end cartographic information systems (CIS) for professional map and atlas makers (Anselin 2012). Over time, conceptual and technically-driven developments in computer graphics, computation and user interfaces have begun to transform the map into something

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that is displayed within a visual toolbox to be used interactively for exploratory data analysis (including multiple representations such as statistical charts, three-dimensional plots and other visual aids to understanding that collectively may be regarded as geovisualisation (Hubbard, Kitchin et al. 2008).

Conventional maps are effective at representing geographical information such as locations, areas, distances and topological relationships by transforming the surface of the sphere using different map projections and have dominated the history of cartographic visualisation. The most common way of adopting conventional maps to describe socio-economic information is to build up thematic maps such as dot maps, proportional symbol maps and choropleth maps, which employ symbols, shadings and colours to represent socio-economic data overlaid on geographical features.

Digital maps are now transmitted over computer networks. The web very quickly became the spatial data delivery mechanism of choice (Masser 1997; Trainor 1997). The combination of maps and the Internet is a significant development, not only for improving distribution but also because it makes a more interactive form of mapping possible. Trends are also evident in the types of maps are available through the Internet, many of which are becoming

interactive, allowing users to use simple queries and zooming. Typically, query functions gave additional information on map objects, the coordinates of a selected point, as well as locator functions. Interactive visualisation methods can increase cognitive resources by providing an additional, external visual resource to the human memory. They may reduce the amount of searching and ease the recognition of patterns as well as enhance understanding of relationships in large amounts of data and information. In addition, they provide a medium that enables the user to have a representation of information that he or she can quickly and easily modify, restructure or consider from a different perspective.

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The different media (maps, diagrams, pictures, text, video, animation and sound) applied in cartography are used to inform about spatial objects, their relationships, and spatial processes. This information process can be efficient only, if the cognitive aspects in media design are considered. A good map does not just instil data in its geographical context, but also serves as an instrument of generalisation and summarisation, helping a user to see insight. In the field of visual thinking the most important function media has is constructing mental models and transforming information into a greater context. It has to give insight into the subject's complete structure; it should support the creation of mental models of the subject's correlations and processes. Maps, abstract graphical presentations, and animations can convey this knowledge. Whilst an air photograph or satellite image may be data rich, a well designed topographic map may effectively present abstract information that reveals unseen patterns not directly visible in the landscape. Interaction with a thematic value-by-area map, such as a representation of election results combined with socio-demographic data, may draw attention to hidden patterns that were not evident in spatial representations of the data

(Andrienko and Andrienko 2007; Andrienko, Andrienko et al. 2010).

Digitising maps provides new challenges that cartographers have not previously considered. These include:

 Visual dynamism, animated and updated in real-time to data changes.

 Multimedia, the integration of text and image with animation, video, and audio.  Interactivity, the opportunity for the user participate in the creation of the map by

changing it.

 Network distribution and data gathering.  3D and virtual environments.

The degree of complexity of what and how the representation is achieved is substantially greater than with static maps.

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When cartographers create thematic maps, they need to consider several important things. The most significant - is the intended audience, since this determines what items should be integrated on the thematic map as reference points in addition to the map's theme: “If we then make the obvious assumption that the content of a map is appropriate to its purpose, there yet remains the equally significant evaluation of the visual methods employed to convey that content” (Robinson 1952 p.17). A classification of representation forms and their potential application areas should be readily available to those exploring geospatial data (Fairbairn, Andrienko et al. 2001). Associated with the application of an appropriate representation method, it is important to ensure that the suitable level of data abstraction for that representation is displayed. Further, it is vital that, once displayed, users are also able to navigate and effectively assimilate all of the data that are available using interactive graphical tools.