A few years ago, some American and international cartography and GIS experts banded together to hold low-key community mapping events under the Maptime label. The international site and the MaptimeTO Twitter account of the Toronto group are dormant, but the idea is alive and well – let’s start a Ryerson University map club under the MaptimeRU banner!
In class the other day, we had a look at “The True Size Of…” web app, which illustrates the size distortion of countries under the Web Mercator projection. Some students already knew the example of Greenland. In most online maps, Greenland looks about as big as the continent of Africa, but its size is greatly inflated under the Mercator projection due to its far-northern latitude. When you pull it towards the equator for size comparison, it shrinks to as little as 7% of Africa, and that is the actual ratio of their land surfaces.
Size comparison maps are popular talking points but they are surprisingly tricky to make in geographic information systems (GIS). After all, we usually aim to map things at their actual location on planet earth’s surface. John Nelson, cartography and user experience specialist at world-leading GIS company Esri, recently posted a blog and video tutorial on “How to make one of those size comparison maps” in ArcGIS Pro. As possible kickoff for a recurring MaptimeRU meetup, I will sit down with interested Geographic Analysis students during study week and replicate John’s instructions as well as try the same in the free and open-source QGIS package.
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