Londonmapper goes #geomob: Visualising London with Cartograms

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.

Gridded Cartogram Animation of Great Britain
(click for larger version)

The second animation (which luckily worked) is that of an animated cartogram series visualising the population shares within 5-year age groups across London. While it does not reflect the changing quantities, this animation vividly demonstrates which generations prefer or can afford to live in certain parts of the city, showing that inner London is the place where younger generations in their twenties and thirties live, while older age groups can also be found in larger numbers in the slightly less densely populated outer boroughs:

Cartogram animation of the demographic structure of London's Population
(click for larger version)

Cartograms can be a powerful way of showing urban structures – socially but also in other areas that affect people’s lives. In Londonmapper we try to use a wide range of cartogram applications to demonstrate their versatility and their use. Cartograms are more than simple diagrams, and cartograms can work at different scales, from the global to the local if appropriate data is available. Some more examples can be found it the full set of slides of my talk:

While the Londonmapper website is still heavily under construction behind the scenes, you can stay up to date with the progress of the project by following us via @londonmapper or liking the Londonmapper Facebook page.

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