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Envisioning Information Lecture 10 – Cartograms: A different way of drawing maps. Ken Brodlie kwb@comp.leeds.ac.uk. Maps have been traditionally drawn to represent area With topography indicated by shading Increasingly we use maps to represent properties about areas
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Envisioning Information Lecture 10 – Cartograms: A different way of drawing maps Ken Brodlie kwb@comp.leeds.ac.uk ENV 2006
Maps have been traditionally drawn to represent area With topography indicated by shading Increasingly we use maps to represent properties about areas Here each state is shaded according to density of population Known as choropleth mapping Choropleth Maps http://www.cdc.noaa.gov/USclimate/states.fast.html ENV 2006
Strengths Weaknesses Discuss Strengths and Weaknesses ENV 2006
The cartogram is a response to these issues Rather than accurately reflect the area and superimpose shading to represent the variable.. .. Distort the area so as to reflect the variable directly Cartograms ENV 2006
Cartograms can be contiguous or non-contiguous Here is population of California by county as a contiguous cartogram Types of Cartogram ENV 2006
.. And now as a non-contiguous cartogram Types of Cartogram ENV 2006
Contiguous and Non-Contiguous Cartograms • Here is the US population example in both styles… ENV 2006
Perimeter-preservation ENV 2006
World Population Cartogram Acknowledgement: Examples taken from Web site of Dr Donald House http://www-viz.tamu.edu/faculty/house/cartograms ENV 2006
Danny Dorling (recently Professor in Leeds) invented a special type of cartogram using circles of different size Types of Cartogram http://www.ncgia.ucsb.edu/projects/Cartogram_Central/index.html ENV 2006
Try the applet at: http://www.mapresso.com/dorling/dorlingexample.html Dorling Cartograms ENV 2006
British county populations evolving… ENV 2006
Acknowledgement: Last two slides from ‘Cartograms for Human Geography’, by D. Dorling, in Visualization in Geographical Information Systems, Wiley. Chernoff Face Cartogram! ENV 2006