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Wikitravel:Geocoding

From Wikitravel

[+] Syntax
- For a destination
- For a listing item
Converting from traditional format
Results
Limitations
Sources for lat/longs
External links

It's possible to encode information about the latitude and longitude of a destination into the destination guide itself. This information will then be used to make special HTML tags to show that the page is related to those lat/long coordinates; some Web spiders and bots use this information to relate a Web page to a geographic location.

[edit] Syntax

[edit] For a destination

The easiest way to add lat/long information to a destination guide article is to use the Geo template. To do so, add the following code to a page:

{{Geo|lat|long}}

Here, lat is the latitude and long is the longitude. Both coordinates must be in decimal form ("45.5", not "45 30 00")--see "Converting from traditional format". For example, Montreal contains the code:

{{Geo|45.5|-73.6}}

Note that only one instance in a page makes sense.

Behind the scenes, we use RDF to encode lat/long information into pages. It's possible to add the RDF for lat/long info directly, without using a template. For example:

 <rdf>
   <> dcterms:spatial [ pos:lat "45.5" ; pos:long "-73.6" ] .
 </rdf>

Which means, roughly, "this page covers something with lat/long of 45.5/-73.6".

[edit] For a listing item

To encode GPS information for attractions, restaurants, etc. in Wikitravel, you can use Wikitravel:Listings experimental feature: it allows lat and long attributes for every listing item.

[edit] Converting from traditional format

To convert from traditional format like lat=N45°30'0", long=W73°36'0", the following can help:

X°Y'Z" = X+(Y/60)+(Z/3600)
for S, add "-" to lat; for N, assume "+"
for W, add "-" to long; for E, assume "+"

[edit] Results

There's special code on the Wikitravel server to check for this kind of RDF data and to re-encode it in HTML <meta> tags when the page is shown. This is useful for some Web spiders and other tools that require that the meta tags be set. Adding the page to GeoURL, for example, will bring it up on their geographic search engine.

[edit] Limitations

Because this system assigns a single geographic point to the entire destination guide, it's only suited to locations that are a) big enough to have a whole guide to themselves and b) small enough that a single point is a reasonable approximation for the location. This mostly means that only city guides are amenable to geocoding in this way.

We'll soon have a way to assign points to individual listings in a guide using Wikitravel:Listings.

[edit] Sources for lat/longs

There are a few Web sites that provide useful lat/long information.

Multimap lets you search for cities in many countries and returns lat/long info
The Getty Thesaurus of Names has lat/long info for most cities in its database
The Global Gazetteer from Falling Rain Genomics, Inc. is another database that gives decimal geocode values for many place names around the world.
Ricahrd Cyganiak's FOAF mapper - find co-ordinates using Google Maps.
http://geonames.org/ - Quick and thorough geocoding
Wikipedia gives co-ordinates for most articles about places