Geotagging Web Pages and RSS Feeds

Providing geographic metadata in Web sites and syndicated feeds can provide users with the ability to search easily for services and articles based on location and proximity.
Geotagging a Web Site

For a Web site, several means of geotagging are available. My previous article explained how to embed the site's geographic information in its DNS entry. Other options also allow this information to be placed within a site or each individual page. These are the older ICBM tags and the newer, more generic geo-structure tags.

The ICBM (original acronym is Intercontinental Ballistic Missile) tags derive from a more historical application, as described in the AntiOnline jargon dictionary:

(Also 'missile address') The form used to register a site with the Usenet mapping project, back before the day of pervasive Internet, included a blank for longitude and latitude, preferably to seconds-of-arc accuracy. This was actually used for generating geographically-correct maps of Usenet links on a plotter; however, it became traditional to refer to this as one's 'ICBM address' or 'missile address', and some people include it in their sig block with that name. (A real missile address would include target elevation.)

ICBM tags are limited to latitude and longitude and do not include other regional information, such as city or country. From Matt Croydon's PostNeo, the RFC (request for comment) of the syntax is as follows:

  

<meta name='ICBM' content="latitude, longitude" />

This tag would be included in your Web page's <head> section.

Another means of embedding geographic metadata is through geo-structure tags. These geo-structure tags can include latitude and longitude information as well as regional information and an extra placename. The placename could contain the specific address of the person or business. Or, it could be useful for providing a location that may not have a specific point but covering a broader region, such as a city or district. The following example is for the Museo Nacional Del Prado, in Madrid, Spain.


<meta name="geo.position" content="40.4157;-3.6947" />
<meta name="geo.region" content="ES-M">
<meta name="geo.placename" content="Paseo  del Prado">

I obtained the geo.position information using Multimap, given the address provided on the museum's Web page. The geo.region uses the ISO-3166-1 Country Names and Region Names specifications. For the US and Canada, this is the abbreviation for the state or province; it varies in other countries. All together, the code for my Web site looks like this:


<meta name="DC.title" content="High Earth Orbit" />
<meta name="ICBM" content="42.4266, -83.49307" />
<meta name="geo.position" content="42.4266;-83.49307" />
<meta name="geo.region" content="US-MI">
<meta name="geo.placename" content="Northville">

As mentioned in the introduction, Multimap provides a location service that offers hotels located within the area of the maps you have selected. This service is provided by the Accommodation Search Engine Network. The Web pages on the ASE site employ the use of commented-out tables to hide the geographic information. The Multimap Web service then pulls this information from each of the hotels' Web pages or backend databases. This method is not recommended, however, because it is not standard and is difficult to use for applications and other Web services. An example of this block is shown below:


<!--
<a name="geo"></a><br>
<table>
  <tr class="bg2">
    <td class="head2">Geographical Information:</td>
  </tr>
  <tr class="bg1">
    <td class="text">
      <span>Accuracy:</span>Property<br>
      <span>Lat:</span>39.894337<br>     
      <span>Long:</span>-83.807657<br>
	  <span>TimeZone:</span>Eastern<br>
    </td>
  </tr>
</table>
-->

Geotagging an RSS Feed

Besides geotagging a Web site, it is possible to geotag the source of an RSS feed as well as the individual articles. By geotagging each article, your feed can provide entries from various locations. Then, these entries can be displayed on a map where users can read about locations that interest them. Alternatively, by geotagging the source of the feed, a directory or opml file could provide feeds based on user-selected locations.

The Resource Description Framework Interest Group (RDFIG) has published a solidifying standard for the geospatial vocabulary. It includes specifying latitude, longitude and, optionally, altitude. This is similar to the geo tags discussed above, with small syntactic differences. Furthermore, the RDF requires you to specify an XML namespace (xmlns) for the WGS84 geodetic reference datum.


<rdf:RDF 
        >
  <geo:Point>
    <geo:lat>55.701</geo:lat>
    <geo:long>12.552</geo:long>
    <geo:alt>52.4</geo:alt>
  </geo:Point>
</rdf:RDF>

The ICBM standard discussed above also can be used in tagging an RSS feed. Again, an XML namespace is used to specify the keywords of the file, and the tags are included either in the header or within the item tags. Here is example from the USGS Earthquake feed of events over 2.5 on the Richter scale in the last 7 days:


<rss version="2.0" >

<item>
	<title>M 3.7, Southern Alaska</title>
	<description>January 02, 2005 03:55:52 GMT</description>
	<link>http://earthquake.usgs.gov/recenteqsww/Quakes/ak00043775.htm</link>
	<icbm:latitude>60.4780</icbm:latitude>
	<icbm:longitude>-152.4355</icbm:longitude>
	<dc:subject>3</dc:subject>
	<dc:subject>pasthour</dc:subject>
</item>

Finally, some Weblog services may prevent users from adding new tags to RSS feeds. In this case, it is acceptable for some sites and packages to embed the geographic information in <dc:subject> tags, as shown below:


<?xml version="1.0"?>
<rss version="2.0"  >
<channel> 

<item>
	<title>Example Title</title>
	<link>http://site.com/geo</link>
	<description>Example Description</description>
	<dc:subject>geo:lat=33.00 geo:long=-44.54</dc:subject>
</item> 

</channel> </rss>

Several Weblog packages already incorporate the ability to specify a geographic location within an entry as well as for the entire Weblog. This geographic information then can be included for users when reading the Weblog through their browsers or through their own aggregators. Each entry, when posted, is assigned either a default location or is given a new location. The following is an example of the geotagged RSS feed generated by Wordpress v1.2:


<?xml version="1.0" encoding="utf-8"?>
<rss version="2.0" 
	
	
	
	
	
>

<channel>
	<title>High Earth Orbit</title>
	<link>http://highearthorbit.com</link>
	<description>LinuxJournal Example</description>
	<icbm:latitude>42.4266</icbm:latitude> 
	<icbm:longitude>-83.4931</icbm:longitude>	<copyright>Copyright 2005</copyright>
	<pubDate>Wed, 05 Jan 2005 18:54:47 +0000</pubDate>
	<generator>http://wordpress.org/?v=1.2</generator>

<item>
	<title>Sample Title</title>
	<link>http://highearthorbit.com/index.php?p=121</link>
	<pubDate>Wed, 05 Jan 2005 18:54:47 +0000</pubDate>
		
	<category>Sample Category</category>		
	<guid>http://highearthorbit.com/index.php?p=121</guid>
	<description>Sample Description</description>
	<geo:Point>
		<geo:lat>42.5021</geo:lat> 
		<geo:long>-83.1454</geo:long>
	</geo:Point>
	<icbm:latitude>42.5021</icbm:latitude> 
	<icbm:longitude>-83.1454</icbm:longitude>
</item>
</channel>
</rss>

For more information on other particular Weblogs, check out the Worldkit Documentation.

______________________

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i have read several articles

nokia 5310's picture

i have read several articles on Geo tagging ,but this one i feel is the best in terms of content and illustrations i myself use to update about geotag or fear being tagged,but this is very detailed information.

Metadata are invisible: enter the Geotag Icon

Bruce McKenzie's picture

Wish I'd come across your summary of the situation earlier, although what is really interesting is how little has changed since 2005. Geotagging is about to surge forward for a number of reasons, but whether geo-location uses meta tags, microformats, or EXIF-GPS it's hard for people to identify content that is location-specific. All these standards are invisible to people (but not to machines). Visibility is one reason why we need a web "standard" geotag icon; others are that it provides visual homogeneity in meaning, is format- and service-agnostic, and encourages development of the semantic web.

This is the rationale behind the Geotag Icon Project, which is a community-designed icon free for use by geotaggers everywhere. See geotagicons.com.

Thanks

teia's picture

Thanks for the article. I wish there were a Drupal module that could do this automatically.

Drupal has great Geo-modules

Anonymous's picture

Drupal actually has great modules for adding GeoRSS and KML:

http://drupal.org/project/georss
http://drupal.org/project/kml

Great Article, got me started on geotagging

grasshoppermind's picture

Your article is an excellent reference for anyone wanting to geotag their own content. However, I also wanted to be able to tag any content. I finally figured out how to do this and I've written up a quick HOWTO: geotag anything article.
Many thanks

Superb Article

dankeblog's picture

I agree, the article is great, and I really hope it'll help me for my future website. Geotagging your content is one of the prospects.

Re:Geo

Falko Paradus's picture

The tools provided includes "WWMX Client Application", which it says will add geotagging to a photograph by dragging and dropping photos to a location on a map (presumably supplied as well).

For more accurate tags, it providess "WWMX Location Stamper", that checks a digital photo's embedded timestamp, correlates it to GPS track files loaded in GPX format, and "WWMX TrackDownload" that can be used to extract tracks from handheld Garmin GPS device (and some others).

Re: Geo

Florian Kater's picture

I don't know about software solutions, but there are a few cameras out
there with GPS built in that will give you that data, along with
direction you are facing and elevation. They are used in real estate,
appraising, etc. You then download from the camera to a map.

Geotagged blogs on Multimap

Richard Rutter's picture

Over the past few months, Multimap has been scraping weblogs for geotags. So far Multimap has collected and mapped nearly 6,000 blogs.

You can search for blogs on any given map by selecting 'Weblogs' from Multimap's local information feature. For example here is a map of blogs in Brighton, UK.

There are more details on Clagnut.

Man, don't you know today's

Diana's picture

Man, don't you know today's statistics? Very interesting to see it.
b.t.w geotap article is very useful.

Mobiletracker reports that

Faustus Erratus's picture

Mobiletracker reports that over the weekend, Yahoo released some
interesting alpha geotagging software called Zonetag.

It's the application for Nokia Series 60 smartphones that automatically
tags photos with the location where they were taken according to info
from the cellular towers the phone was connected to at the time. Photos
are then sent to Yahoo's photo sharing site, Flickr.

A2B - some extra features in last few days

Sam Critchley - A2B's picture

Hi Andrew (everyone),

Many thanks for writing the article - great article (which I will definitely be bookmarking) and it's very exciting for us at A2B to get a mention!

I think the real challenge for the future of the whole geotagging area is integration with mapping. Wealthy commercial applications can afford the huge prices for mapping data, but the USA is about the only country where full country mapping information is available for free (called "TIGER data" from the US Census), and commercial services are charging a LOT for mapping data (which A2B can't afford at the moment).

Anyway, thought you and your readers might like to know about a couple of new extras on A2B which add to what you wrote:

- RSS feeds. You can now autogenerate an RSS feed URL which shows "most recently added/updated sites within XX kilometres/miles" of your site.
- Blog/site buttons - you can now autogenerate the link for an "A2B Nearby" button for your blog/site which will show your visitors which other sites are geographically nearest to yours.
- Map-based A2B searching - you can now put up your own map image file (including scanned maps, assuming copyright permission) and generate imagemap HTML to put on your site.

Details in the latest A2B newsletter at http://forum.a2b.cc/viewtopic.php?t=26

Many thanks,

Sam

thanks!

Ben LeMasurier's picture

Thanks for the great article. I think I will start to include this in all the sites I build. Is there a known lat/long search engine?

thanks again,

Ben

uidzer0.org

geourl.org

neilp's picture

yea - you should check out geourl.org it (sort of) does lookups based on latitude and longitude.

re: Is there a known lat/long search engine?

Richard Rutter's picture

The map information are below every map on Multimap.com displays latitude and longitude. So you can search for any location world-wide and Multimap will give you the map and associated coordinates below.

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