Today I was invited to give a presentation at the quarterly #geomob meetup for location based service developers which this time took place at the Google Campus in East London. In my talk I gave a short preview of the Londonmapper project that I am working on with my colleagues and the Trust for London. Unfortunately technology played some tricks on us and some of the animated bits and content did not show up during the presentation, so that I promised to put these on my blog alongside the slides of the talk. Here we go…
This first animation was an introduction into showing how cartograms work in general. I used a gridded population cartogram animation for Great Britain which I created years ago, demonstrating the approach of using a gridded cartogram to allow other layers being used in the transformed map. The following map (which is rather drafty as it was only a conceptual exercise) shows Great Britain overlaid with a topographic layer indicating the land elevation, as well as some key rivers and a selection of the motorway network. During the animation this map transforms from a conventional land area map into a gridded population cartogram where each grid cell is resized according to the total number of people living there. While the grid cells change their size, the other geographic layers are changed accordingly, so that the final cartogram shows these layers in relation to the population distribution, i.e. at which elevations do people live and how are people linked to major roads. The animation also demonstrates the magnifying lens effect in the most densely populated areas. Motorways and even the curvy shapes of the river Thames become visible now which at such a scale cannot be seen from a normal map. Gridded cartograms hence help to highlight details in these areas that are most relevant in the transformed space.

(click for larger version)

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