Map of the Week 10-17-2011: Gridded Population Cartogram of China

The equal-population map shows a gridded population cartogram in which every grid cell is resized according to the total number of people living there.  From: http://www.viewsoftheworld.net/?p=1738
Thanks, Kristen Grady, for sending me the cartogram!

         
Many of you (and ALL of you who have had a GISc class with me!) probably know by now that I LOVE cartograms.  And I have been a huge fan of Danny Dorling and his Cartogram Factory for years (and by “Cartogram Factory” I am not alluding to some Dickensian assembly line of cartogram makers, but something more akin to Andy Warhol’s Factory of unique and cutting-edge creativity, but maybe minus some of the decadence!). 

Cartograms, or value-by-area maps, are a very innovative type of thematic map whereby the geographical areas are depicted not by their actual geographic size (as is usual on most maps) but are sized by a function of some ancillary variable, such as population, GDP, or life expectancy, for example.  In other words, the variable to be mapped is substituted for land area in showing the size of the geographical units.  According to the “Cartogram Central” website of the University of California at Santa Barbara, http://www.ncgia.ucsb.edu/projects/Cartogram_Central/types.html there are three types of cartograms: contiguous, non-contiguous, and Dorling.  See Danny Dorling’s World Mapper website at http://www.worldmapper.org/  and also see Gretchen Culp’s review of the book Atlas of the Real World: Mapping the Way We Live, by Dorling, Newman, and Barford, at http://geographer-at-large.blogspot.com/2011/02/atlas-of-real-world-mapping-way-we-live.html

WorldMapper's Grid-Based World Population Cartogram (2000), focusing on sub-national level data, from the ESRI website at http://www.esri.com/news/arcuser/0110/cartograms.html

WorldMapper's World Population Cartogram based on national level data, from  http://www.esri.com/news/arcuser/0110/cartograms.html

One of the potentially problematic issues with cartograms is that in order for the map viewer to correctly interpret the cartogram, s/he has to be familiar with the original geography of the mapped area.  If not, then the re-sizing of the units of analysis based on the ancillary variable (in the case of the map above, by population) will be meaningless.  This is one of the oft-cited drawbacks of cartograms, and I suspect, one of the main reasons why they haven’t become as widely-used as choropleth maps or dot density maps.  This drawback can be at least partially mitigated by including a map of the standard geography of the mapped area as a kind of a “locator” or reference map, which becomes even more important when the geography in question is likely to be poorly understood by the map viewer.  The map of China shown here does just that, making it easier for those not very familiar with China’s geography able to discern the areas of high population concentrations, and where there are relatively smaller populations.

A few months ago, I wrote a post about the newly emerging mega-regions, one of which was the Pearl River Delta area in China. http://geographer-at-large.blogspot.com/2011/02/megaregions-is-this-our-future.html  This mega-region was being touted as potentially the largest city conglomeration in the world, with over 40 million people.  The British Telegraph Newspaper stated: “China is planning to create the world’s biggest mega city by merging nine cities to create a metropolis twice the size of Wales with a population of 42 million.”  http://www.telegraph.co.uk/news/worldnews/asia/china/8278315/China-to-create-largest-mega-city-in-the-world-with-42-million-people.html

       The map above was created to counter, or at least temper, some of the hysterical buzz surrounding this story.  The cartogram’s creator, Benjamin D. Hennig of the University of Sheffield’s SASI group, says “This map makes the plans of a more integrated Pearl River Delta region more understandable, and perhaps slightly less exciting for those who interpreted the news as the creation of a new megacity, rather than the logical step in connecting an already populous region.” http://www.viewsoftheworld.net/?p=1738

See the SASI post and slide show on creating gridded population maps at Re-Mapping the World’s Population in ArcUser and Slideshare http://www.viewsoftheworld.net/?p=701

See their PDF of creating cartograms for data visualization at http://www.viewsoftheworld.net/data/ArcUser2010_hennigetal.pdf

As shown in the two world population maps above, there is a big difference in mapping data at tha national level versus at the sub-national level using the gridded approach.

Pulse of the Nation: Maps Based on Twitter Activity

U.S. Mood throughout the day, inferred from Twitter

© 2010 Alan Mislove, Sune Lehmann, Yong-Yeol Ahn, Jukka-Pekka Onnela, J. Niels Rosenquist. Some rights reserved. Images, poster, and movie are shared under the Creative Commons Attribution 3.0 License.

More cartograms!  This series of maps is about degrees of happiness and times of the day, based on tweets.  Check out the animated map sequence.  Thanks for sending the link, Gretchen!

http://www.ccs.neu.edu/home/amislove/twittermood/  

And in another twitter-related map, Daniel Huffman interpolated the ratio of tweets containing curse words with total number of tweets to produce an isopleth map of cursing activity.  The comments below the map give a lot of detail on his methodology and data in constructing the map.  http://cartastrophe.wordpress.com/2011/01/24/no-swearing-in-utah/   Thanks for sending me this, Andrew M. (nearly a month ago!).  The Map Monkey moves slowly sometimes, but actually it worked out really well to pair it with this other Twitter map! 

Detail of Four Corners Area

The Atlas of the Real World: Mapping the Way We Live

 

Cartogram by Danny Dorling - Total Population

So, here we have something new and different: a book review by a guest blogger, GM Culp!  Thank you for contributing to the random notes: geographer-at-large blog!  Nice review, and of course, we LOVE Danny Dorling! 

The Atlas of the Real World: Mapping the Way We Live,

by D. Dorling, M. Newman and A. Barford

Reviewed by GM Culp, 02.19.2011

Chances are that while surfing information design or geography blogs you’ve encountered graphics similar to the one above. Perhaps you’ve seen one in poster form on the wall of the GIS lab or in the New York Times.  This cartogram is by Daniel Dorling, Professor of Human Geography at the University of Sheffield.  Although Dorling did not invent this form of presenting geographic data (hand drawn cartograms started appearing in the mid to late 1800s), he can definitely be credited with popularizing it among the data visualization set.  Back in the 1960s, Waldo Tobler developed a method utilizing the root mean squared error of unit densities to generate cartograms with a computer.  

Dorling’s cartograms are created using a method developed by two physicists, Michael Gastner and Mark Newman, and is based on principles behind the diffusion of fluid.  This software and datasets are available gratis from Dorling’s website [http://www.worldmapper.org/]. 

I received the revised and expanded edition of Dorling’s The Atlas of the Real World  (co-authored by Mark Newman and Anna Barford) as a holiday gift from my mother-in-law (along with two Toblerone candy bars…clever and delicious).  I must admit that prior to reading this text I was a bit put off by cartograms.  The idea of distorting land area seemed like a bad idea… particularly in an era when geographic illiteracy is commonplace among American school children.  [See the geographic literacy “quiz” and alarmingly sad results at: http://www.nationalgeographic.com/roper2006/]

I was also a bit perplexed by Dorling’s Easter egg color palette.  All this and more is explained in the book’s introduction.  Dorling justifies the cartogram’s warping of geographic space by pointing out that all projections distort.  We live on a spherical planet thus some bending and stretching must take place to create a flat map.  The color palette was actually quite thoughtfully chosen.  Europe is represented by various shades of purple, the Americas by blues, Africa by greens and Asia by ochres.  The colors are different enough to allow users to easily identify areas in what are often severely distorted maps.  The palette is also used to color code the accompanying graphs.  Many of the data used comes from the World Bank and various United Nations programs.  The Atlas of the Real World is heavy, both physically and metaphorically.  There are 382 maps ranging in topics from poverty to deforestation to deaths from preventable diseases.  It should come as no surprise that the United States is one of the wealthiest nations [162] and also a top consumer of resources [343, 344, 348, 349] with the greatest military spending [310], number of prisoners [323], arms exports [311] and nuclear weapons [313].  Our ecological footprint is the largest [354] and we have the extinguished the greatest number of species [355].  While we are eating McDonalds [076], 48% of Bangladeshi children are underweight [175].  There are quite a few surprising and interesting tidbits, too.  Did you know that Monaco has 25,641 meters of road per square acre [052] or that Sweden generates over 7500 kilowatt hours of nuclear power per person [062]?  The majority of the world’s 150 million atheists live in East Asia [382] while 97% of spiritualists reside in South America [380].  Dorling’s cartograms are tragically beautiful.  Consider the map People Killed by Drought [303] where Africa is so distorted it resembles a lady slipper orchid or People Killed by Volcanoes [302] where one might mistake South America for a bouncing beach ball.  The Atlas of the Real World is an important volume and would be a welcome addition to any human geography, cartography, environmental justice, or information design library.

[http://www.amazon.com/Atlas-Real-World-Mapping-Expanded/dp/0500288534/ref=ntt_at_ep_dpi_1]