4.5 Dynamic mapping

Dynamic maps have been defined as maps that change in response to user action or to changes in data to which they are linked (MacEachren, 1998). However, dynamic mapping is a relatively new technology, and a standard definition for the term ‘dynamic mapping’ has not yet emerged (Cromley and McLafferty, for example, use a slightly different definition to this). Since most users do not have access to specialist GIS software, dynamic mapping now predominantly entails web-based access to spatial databases. End users can use a web browser to create basic maps and query databases.

The technical issues involved in developing web-based dynamic mapping are beyond the scope of this object. However, numerous products now exist to enable dynamic mapping over the web, including Intergraph’s GeoMedia WebMap, ESRI’s ArcWeb Services, MacroMedia Flash, and SKE Dynamic Atlas. Particular difficulties in developing dynamic mapping applications include the variation in user hardware specifications, such as screen resolution and ability to perform any client-based processing or run plug-ins. Further issues include the need to tailor functionality to suit the needs of the users and to authenticate users where data use is restricted. Enabling interactive manipulation of maps requires careful thought. For example, where users can change the level of zoom on a map, there need to be map generalisation rules that govern the level of detail visible on screen according to the map extent.

In a health context, target users are likely to be either health professionals accessing spatial data over an intra-net or the general public accessing data via the internet. Providing intra-net users with dynamic mapping capabilities has several advantages. If health professionals are given access to basic utilities such as creating maps and spatial querying of data via an intranet, then this can reduce the workload of the GIS analyst. If health professionals can produce basic cartography and perform simple spatial queries using dynamic maps, this reduces their reliance on the GIS analyst and prevents delays in cartographic production.

State of the Art web-based GIS can play an important part in the development of Public Participation GIS

(Banger, 2004)

 
One of the primary objectives of allowing the general public to query health data is to improve public participation in decision-making. It has been suggested that active community involvement will increase the chances of a public health campaign’s success. Dynamic mapping can provide the public with access to the raw spatial data that are used to plan such campaigns, so enhancing community involvement. Dynamic mapping thus forms part of a broader move towards Public Participation GIS (PP-GIS). Aside from the suggestion that public participation increases the chances of successful public health policy, it may also be argued that the public have a right as tax-payers to health statistics for their area. This is especially true of the health risks associated with environmental exposure to pollutants, where there may be considerable public mistrust of government.

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