Extension:Gis

The gis extension implements the   tag and the Map sources function.

The extensions can be enabled individually, but the concept is certainly more powerful when they are all enabled.

See en:Wikipedia:WikiProject Geographical coordinates for more information.

Bugs
There are currently no translations.

The database and neighborhood elements are not yet available in CVS.

Install instructions
Move the extensions/gis directory to the $mediawiki/extensions directory and add these lines to LocalSettings.php:

$wgMapsourcesURL = "/phase3/extensions/gis/index.php"; include( "extensions/gis/geo.php" );

The geo tag
The &lt;geo&gt; tag allows entry of geographical coordinates something in style with RFC1876. For example:

&lt;geo&gt;48 46 36 N 121 48 51 W&lt;/geo&gt;

It is designed to be flexible, and easy to use.

Variations of the above allows specification with decimals in various forms, allowing less or more precision. Additional meta-data can also be specified as attributes for the location, like this:

&lt;geo&gt;48 46 36 N 121 48 51 W type:mountain region:US scale:100000&lt;/geo&gt;

In the rendered article, the tag will be replaced with 48&deg;46'36N 121&deg;48'51W, which is also a Wikilink to a page of map resources for that point.

The main geo tag advantages are:


 * 1) Consistent markup for coordinates.
 * 2) Consistent rendering of coordinates.
 * 3) Wikipedia articles with coordinates will get a 'geo.position' meta tag, making it compatible with Internet geographic resources, such as geourl.org.
 * 4) Serves as an enabler for the two other extensions.

The map sources
The map sources extension is the target of the &lt;geo&gt; tag wikilink, and provides a page of available Internet map resources, in a manner much like the ISBN resource page. The extension provides functionality to preload external URLs with coordinates, so that most maps are essentially one click away.

There are currently 30 different built in replacement strings, supporting various form of specification of scaling and coordinates, such as UTM, OSGB36 and CH1903.

There exists specialized versions of the map sources page for various regions (like US and GB). For the global version, there are at present preloaded pointers to around 20 different map engines.

In addition to the maps, there is a pointer to GeoURL.org, which lists nearby resources on the Internet.

There is also a direct link for the open source NASA World Wind software, allowing a new, interactive way of experiencing for aerial imagery and topological data. World Wind has a plug-in layer for Wikipedia articles that are tagged with a geographic coordinate.

Assuming the enabling of the gis database extension, there is also a pointer to neighborhood articles in Wikipedia, listing the articles with Wikilinks, and their distance and direction from the present point.

The database
The geo database keeps track of all articles in Wikipedia with geographic coordinates, and provides the data source for the neighborhood information, as well as the data source for other external mechanisms taking advantage of the Wikipedia geographical information, such as the NASA World Wind Wikipedia overlay.

Additionally, the geo database will provide data for the future Wikimap, so that the maps produced by Wikimaps will contain all the relevant information from Wikipedia as clickable points. For this, geo attributes are crucial: Airports really should appear as airports on the map, mountains as mountains, and cities as cities, with the right magnitude.

Status
Currently the geo and map sources extensions are quite well developed, and have been tested for a time on an external server. Additionally, a few thousand articles in the en: Wikipedia are marked with geographic coordinates using an interim solution with templates, as a proof-of-concept. They will be converted to the geo tag if this extension gets enabled for the English Wikipedia. That will also solve the current problem with coordinates as arguments for infobox templates. Collection of data points have been done with an interim, external solution based on some Perl scripts.

The database extension has also been implemented, but some performance and security issues remain to be investigated.

Acknowledgements
Magnus Manske has been extremely helpful in the work on integration with Wikimaps.

I would also like to give a big thank you to all participants in WikiProject Geographical coordinates who have helped immensely with suggestions and practical work.

Egil Kvaleberg en:User:Egil