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Links

The following list contains links to other sites of possible/probable interest.

• ActivePerl
  The main script/program of interest here is written in Perl and requires three add-ons: GD, GD::Polyline, and Geo::ShapeFile. One way to get the necessary software is ActiveState's ActivePerl product. It's free for personal use and available for all of Windows, MacOS, and Linux. All three add-ons are available through the ActivePerl package manager.
  
  
• Strawberry Perl
  Another free Perl installation for Windows is Strawberry Perl. It has the advantage of including a complete C/C++ development kit which supports the "normal" Perl way of acquiring things through CPAN. It has the disadvantage that you have to acquire things through CPAN.
  
  
• Mark Newman's cart Pages
  Mark Newman provides several pages with information about the cart program which implements the method described in the paper "Diffusion-based method for producing density equalizing maps", Michael T. Gastner and M. E. J. Newman, Proc. Natl. Acad. Sci. USA 101, 7499-7504 (2004), and the program's source code. Cart does the heavy lifting for the contiguous cartograms my software produces. The Worldmapper site linked below uses the same algorithm (and quite possibly the same code).
  
  
• FFTW Home Page
  The FFTW discrete Fourier transform library is used by the cart program.
  
  
• PROJ.4
  PROJ.4 is a collection of cartographic projections software. The cs2cs program that is part of the collection can be used to convert outline information from one projection to another. For example, there is lots of map data available with coordinates given in latitude and longitude. In many cases, an alternative such as the Albers equal-area conic projection (used by the US Geological Survey and US Census Bureau, developed by Heinrich C. Albers in 1805) is preferred. Maps generated by my software default to the Albers projection, with options for a couple of others.
  
  
• Ffmpeg
  Ffmpeg is a cross-platform command-line Swiss Army knife for video and audio conversion. Cartogram.pl invokes ffmpeg to convert sequences of PNG frames into MP4 video clips.
  
  
• ArcGIS Cartogram Geoprocessing Tool
  ArcGIS is a commercial mapping tool sold by ESRI. ESRI is a leading vendor of geographic information system software and created the shapefile format. That file format (a "shapefile" is actually three or more related files) is regulated by ESRI and is a (mostly) open specification. The linked page allows ArcGIS users to download and install a cartogram add-on.
  
  
• ScapeToad
  ScapeToad is a Java implementation of the Gastner/Newman algorithm together with a graphical user interface. ScapeToad works with ESRI shapefiles.
  
  
• Shipeng Sun's Home Page
  Shipeng Sun is author of a paper presenting a new algorithm for producing contiguous cartograms, "A Fast, Free-Form Rubber-Sheet Algorithm for Contiguous Area Cartograms", Sun, S., International Journal of Geographic Information Science 27 (3): 567-93 (2013). A Windows-only program for producing cartograms using the algorithm is available through his home page.
  
  
• Shawn Allen's Cartogram Tool
  Shawn Allen has written a cartogram tool in JavaScript that implements Dougenik, Chrisman, and Niemeyer's 1985 algorithm. The animation changing from one thematic variable to another is pretty cool.
  
  
• Worldmapper
  Worldmapper has nearly 700 contiguous cartogram world maps illustrating a vast array of population and other variables. In addition to the cartograms, Worldmapper provides access to the data used to generate the cartograms, including intermediate calculations. Sources for the data are also identified. Many of the maps are available as PDF posters.
  
  

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Last updated Feb 23, 2018