ENV Envisioning Information Lecture 10 – Cartograms: A different way of drawing maps Ken Brodlie

ENV Choropleth Maps 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

ENV Discuss Strengths and Weaknesses StrengthsWeaknesses

ENV Cartograms 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

ENV Types of Cartogram Cartograms can be contiguous or non-contiguous –Here is population of California by county as a contiguous cartogram

ENV Types of Cartogram.. And now as a non-contiguous cartogram

ENV Contiguous and Non-Contiguous Cartograms Here is the US population example in both styles…

ENV Perimeter-preservation

ENV World Population Cartogram Acknowledgement: Examples taken from Web site of Dr Donald House

ENV George Bush – Victory large or small?

ENV Types of Cartogram Danny Dorling (recently Professor in Leeds) invented a special type of cartogram using circles of different size

ENV Dorling Cartograms Try the applet at:

ENV British county populations evolving…

ENV Chernoff Face Cartogram! Acknowledgement: –Last two slides from Cartograms for Human Geography, by D. Dorling, in Visualization in Geographical Information Systems, Wiley.