cartogram
American Heritage Dictionary:
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car·to·gram
Oxford Dictionary of Statistics:
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cartogram
A distorted map in which regions are drawn not to an areal scale but to some other scale such as population. Some cartograms attempt to retain the shape of the geographical region they represent; others, such as the rectangular cartogram illustrated opposite, use a single shape to represent all regions of equal importance.
Rectangular cartogram. The diagram shows variation in turnout (the proportion of the electorate who actually cast their votes) in the British constituencies in the 1992 general election. Each constituency is represented by a rectangle whose area indicates the physical size of the constituency. The big conurbations (Greater London, Birmingham, Manchester, etc.) are indicated as outlined regions. Somewhat paradoxically, turnout is lower in city centres than in the rural constituencies.
Casement plot. The relation between the time intervals before and after eruptions of *Old Faithful, shown separately for different lengths of the intervening eruption.
Oxford Dictionary of Geography:
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cartogram
Broadly defined as a map using statistical symbols, a more specialist usage defines a cartogram as a type of map transformation based on a scale other than a true scale. For example, a voting map of Britain may show the size of counties in relation to the numbers of voters in each electoral unit, or an economic cartogram of the world may show countries drawn in proportion to their per capita GNP. Certain ‘rules’ are followed, as far as possible: the shapes of the countries and regions involved are preserved, although often stylized, and they are positioned in the correct geographical locations with respect to each other. Obviously, distortions occur, but the trick is to preserve the original shapes and positions enough to make the units recognizable; computers have helped in this, but the best examples are still produced by hand.
Saunders Veterinary Dictionary:
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cartogram
A map showing the distribution of a population by area.
Random House Word Menu:
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categories related to 'cartogram'
- Maps and Cartography - cartogram: type of map in which size of nations is based on something other than area
Wikipedia on Answers.com:
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Cartogram
A cartogram is a map in which some thematic mapping variable – such as travel time or Gross National Product – is substituted for land area or distance. The geometry or space of the map is distorted in order to convey the information of this alternate variable. There are two main types of cartograms: area and distance cartograms.
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Area cartograms
An area cartogram is sometimes referred to as a value-by-area map or an isodemographic map, the latter particularly for a population cartogram, which illustrates the relative sizes of the populations of the countries of the world by scaling the area of each country in proportion to its population; the shape and relative location of each country is retained to as large an extent as possible, but inevitably a large amount of distortion results. Other synonyms in use are anamorphic map, density-equalizing map and Gastner map.[1][2][3]
Distance cartogram
A distance cartogram may also be called a central-point cartogram or isochronic cartogram. This form is typically used to show relative travel times and directions from vertices in a network. Compare the maps of travel time for the London Underground below.
Travel Time Tube Maps for Heathrow (left) and High Barnet (right), with an unaltered map for reference (center).
Production
Net contributors
-5000 to -1000 euro per capita
-1000 to -500 euro per capita
-500 to 0 euro per capita
Net recipients
0 to 500 euro per capita
500 to 1000 euro per capita
1000 to 5000 euro per capita
5000 to 10000 euro per capita
10000 euro plus per capita
n/a
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One of the first cartographers to generate cartograms with the aid of computer visualization was Waldo Tobler of UC Santa Barbara in the 1960s. Prior to Tobler's work, cartograms were created by hand (as they occasionally still are). A number of software packages generate cartograms.
See also
Further reading
- Campbell, John. Map Use and Analysis. New York: McGraw-Hill, 2001.
- Gillard, Quentin. "Places in the News: The Use of Cartograms in Introductory Geography Courses." Journal of Geography. 78 (1979): 114-115.
- Tobler, Waldo. "Thirty-Five Years of Computer Cartograms." Annals of the Association of American Geographers. 94 (2004): 58-73.
- Vescovo, Victor. "The Atlas of World Statistics." Dallas: Caladan Press, 2005.
References
- ^ Michael T. Gastner; Mark E. J. Newman (2004). "Diffusion-based method for producing density equalizing maps". Proceedings of the National Academy of Sciences 101 (20): 7499–7504. arXiv:physics/0401102. Bibcode 2004PNAS..101.7499G. doi:10.1073/pnas.0400280101. PMC 419634. PMID 15136719. http://www.pnas.org/content/101/20/7499.full.
- ^ Gallery of Data Visualization - Bright Ideas
- ^ UNEP GRID Ardenal: Anamorphic Maps
External links
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Wikimedia Commons has media related to: Cartograms |
- Cartogram Central
- Multiple cartograms showing the results of the 2008 U.S. presidential election
- Worldmapper collection of world cartograms
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American Heritage Dictionary
The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.
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Oxford Dictionary of Statistics
A Dictionary of Statistics. Second edition revised. Copyright © Oxford University Press, 2008. All rights reserved.
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Oxford Dictionary of Geography
A Dictionary of Geography. Copyright © Susan Mayhew 1992, 1997, 2004. All rights reserved.
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Saunders Veterinary Dictionary
Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved.
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