Friday, February 3, 2012

Game Changer: Open Source Mapping in Windows

One of the trepidations I have with teaching mapping courses using open source is that it usually requires some modicum of programming which is always way beyond the scope of any beginner class about making maps.  In addition, open source tends to favor linux or unix based tool chains that require config/make/make install tap dance before starting anything. This is akin to telling folks that they will need to forge their tools before they can start building a dog house. Finally, 84% of the computers and (in my experience) 100% of the training facilities in the world run some variant of Windows, which means that people have to depend on the kindness of strangers who compile and distribute Windows binaries.

While the sheer number of mapping related programs has exploded, the learning curve has yet to flatten significantly so that the average Windows user can produce maps without sending sizable checks and bits of their soul to Redlands. Until now. 

Two tools, QGIS and Postgres/PostGIS, have had windows implementations and are well on their way to being polished products with fantastic user communities that extend their capabilities. The QGIS plug-in architecture has fostered a number of repositories with plugins ranging from basic geometry manipulation to domain specific analysis. The Windows 1.7.3 Wroclaw version also includes GRASS and msys, which is a shell environment containing common unix tools such as sed and awk – mainstays in my data crunching/munging tool kit.

Postgres/PostGIS installation is also very polished thanks to EnterpriseDB's Stackbuilder installer. It simplifies PostGIS installation as well as providing ODBC drivers needed for communicating with Microsoft products. PostGIS 2.0 has not been released and is not included in the current installer, but the final release will include routing, geocoding, and many improvements that are already available in the alpha 2.0 release.

The real game changer is the release of TileMill for Windows.  TileMill is a cartographic studio that uses Mapnik, which is described:
"Mapnik is about making beautiful maps. It uses the AGG library and offers world class anti-aliasing rendering with subpixel accuracy for geographic data." 
That means no more jagged lines that you see on both web maps and print maps produced by commercial GIS programs. TileMill uses MSS (Map Style Sheets) to make maps; it's rather bare bones in that there is no tool to select a feature and set the line style, color, or fill in a menu. You have to create each style using MSS in a TileMill editor, fortunately TileMill syntax is simple and mirrors CSS so that designers can use it. Calling TileMill a cartographic studio is a stretch. For example, it lacks tools for automatically symbolizing categorical or continuous variables, or include a basic set of cartographic markers.  What it does do very well is produce beautiful maps. Labeling is generally well done in terms of distribution, collision avoidance, and kerning along curves. Output formats include png, svg, pdf and mbtiles, which is a compact tile format that is gaining traction especially for mobile devices.

Red dot fever is a meme that won't die*
The lack of a really good cartographic tool has been the achilles heel for the adoption open source mapping, but TileMill plugs that deficiency. Windows users, henceforth known as the 84%, can now store and manipulate geospatial data in PostGIS, analyze and modify the data in QGIS, and publish it using TileMill.

This is an introduction to series of articles on using open source mapping software in Windows. The next install will cover installation, finding data, and loading it into PostGIS.

*Yes, that's an OSX screenshot, that's what happens when I stay up past my bedtime. On second thought, let's just say I'm lazy.

UPDATE: Second part in this series

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