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The gis extension implements the <geo> 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

1. There are currently no translations.
2. This software needs more testing.

Install instructions

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

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

If the $wgMapsourcesURL is omitted, the geo tag will not include a link to the map sources. If the database.php is omitted, there will be no database, so the neighborhood and map support functions are disabled.

In addition, if using the database function, the gis database must be enabled. Currently, this has to be performed directly in MySQL, where the following table needs to be defined:

   USE wikidb;
   CREATE TABLE wikipedia_gis (
       gis_id int(8) unsigned NOT NULL,
       gis_latitude_min real NOT NULL,
       gis_latitude_max real NOT NULL,
       gis_longitude_min real NOT NULL,
       gis_longitude_max real NOT NULL,
       gis_region char(2) binary default ,
       gis_type char(12) binary default ,
       gis_type_arg char(12) binary default ,                                                                                
       KEY gis_id (gis_id),
       INDEX gis_latitude_min (gis_latitude_min),
       INDEX gis_latitude_max (gis_latitude_max),
       INDEX gis_longitude_min (gis_longitude_min),
       INDEX gis_longitude_max (gis_longitude_max)
   );

Extensions

The geo tag

The <geo> tag allows entry of geographical coordinates something in style with RFC1876. For example:

  <geo>48 46 36 N 121 48 51 W</geo>

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:

  <geo>48 46 36 N 121 48 51 W type:mountain region:US scale:100000</geo>

In the rendered article, the tag will be replaced with 48°46'36N 121°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.

In addition to a point, the tag can also specify a box by giving two, opposite corner points, like this:

  <geo>48 45 N 121 47 W to 48 47 N 121 49 W</geo&gt

The map sources

The map sources extension is the target of the <geo> 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 http://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. Note that this requires the worldwind URL tag to be enabled in Wikipedia.

The URL format is:

   $mediawiki/extensions/gis/index.php?geo=GEOBODY

where GEOBODY has exactly the same format as the body of the geo tag.

The neighborhood function

Assuming the enabling of the gis database extension, there is also a function to display neighborhood articles in Wikipedia. It lists the articles with Wikilinks, and their distance and direction from the current point.

The URL format is:

   $mediawiki/extensions/gis/index.php?near=GEOBODY&dist=DIST

where GEOBODY has exactly the same format as the body of the geo tag. If a type is specified, only points that use this particular type will be included. DIST is the max distance from the point in question, measured in kilometers.

The map support function

Assuming the enabling of the gis database extension, there is also a function to articles in Wikipedia covering a certain area. The opints are listed in Wikimap format. This function is meant for use by other functions, so the raw x-wiki format is ususally used, not HTML.

The URL format is:

   $mediawiki/extensions/gis/index.php?maparea=GEOBOX&action=raw

where GEOBOX has exactly the same format as the body of the geo tag, when a box is specified using the to keyword. If a type is specified, only points that use this particular type will be included.

The version function

To display the version of the gis extension, use the URL format:

   $mediawiki/extensions/gis/index.php?version

where GEOBOX has exactly the same format as the body of the geo tag, when a box is specified. If a type is specified, only points that use this particular type will be included.

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, and is available. But it is likewise not yet enabled for any of the Wikipedias.

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 en:WikiProject Geographical coordinates who have helped immensely with suggestions and practical work.

— Egil Kvaleberg en:User:Egil