Presentation by Sarah Battersby on the Web Mercator Projection

Sarah Battersby of the University of South Carolina will be giving a presentation on the Web Mercator projection in 180 Science Hall, on Nov. 2, 2012, at 3:30 pm.


Web Mercator: A good use for an old map projection, or just another visit by a mental imperialist?

For years there has been debate over the impacts of the Mercator projection and its influence on our perception of geographic areas and representation of spatial patterns. While the map has fallen out of general use for paper maps, a new flavor of the projection (Web Mercator) has become the standard map projection for many web mapping services, such as Google Maps, Bing, and ArcGIS online. Unfortunately, while Web Mercator has numerous technical benefits for web mapping, there are significant concerns about its acceptability for general purpose mapping of large geographic areas – for instance, accuracy of spatial relations and calculations, and, of course, a return of the old suggestion that use of Mercator is influencing our global-scale cognitive maps. Though recent(ish) research (late 2000s) has indicated that Mercator may not have had as much impact on our cognitive maps as was suspected earlier, it seems that as we shift into a time of more extensive web map use we may need to reconsider the potential impacts of the projection. In this presentation, I will evaluate the technical merits of the “new” Web Mercator projection, the cognitive and educational impacts, and best-practice challenges that face everyday users and designers of web maps. I will also present some exciting developments in map projection research from across the projection research community that may help move us towards better alternatives that would be effective for both global- and local-scale web mapping. My goal is not to demonize the projection, but to provide a view of the good, the bad, and the questionable aspects of the projection that we should be attentive to (in research and cartographic design) as we move towards increased use of web mapping for display and analysis.

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