Geotagging

Geotagging is a popular feature on several social media platforms, such as Facebook and Instagram.

Facebook users can geotag photos that can be added to the page of the location they are tagging. Users may also use a feature that allows them to find nearby Facebook friends by generating a list of people according to the location tracker in their mobile devices.{{cite web |url=https://techcrunch.com/2012/06/24/friendshake-facebooks-new-mobile-feature-for-finding-people-nearby-and-a-highlight-killer/ |title= Facebook's New Mobile Feature For Finding People Around You |date= 24 June 2012 |access-date=2016-04-19}}

Instagram uses a map feature that allows users to geotag photos. The map layout pin points specific photos that the user has taken on a world map.

{{main|Geotagged photograph}}

Two main options can be used to geotag photos: capturing GPS information at the time the photo is taken or "attaching" geocoordinates to the photograph after the picture is taken.

In order to capture GPS data at the time the photograph is captured, the user must have a camera with built in GPS or a standalone GPS along with a digital camera. Because of the requirement for wireless service providers in United States to supply more precise location information for 911 calls by September 11, 2012,{{cite web |url=http://www.fcc.gov/cgb/consumerfacts/wireless911srvc.html |title=Wireless 911 Services |access-date=2010-07-15}} more and more cell phones have built-in GPS chips. Most smart phones already use a GPS chip along with built-in cameras to allow users to automatically geotag photos. Others may have the GPS chip and camera but do not have internal software needed to embed the GPS information within the picture. A few digital cameras also have built-on or built-in GPS that allow for automatic geotagging.{{cite web|url=https://www.fireflyarticles.com/photography/photographers-have-several-camera-options-for-geotagging-pictures-with-gps-points-22.html|title=Photographers Have Several Camera Options for Geotagging Pictures with GPS Points|access-date=2018-06-23|archive-date=2018-06-23|archive-url=https://web.archive.org/web/20180623061211/https://www.fireflyarticles.com/photography/photographers-have-several-camera-options-for-geotagging-pictures-with-gps-points-22.html|url-status=usurped}}

Devices use GPS, A-GPS or both. A-GPS can be faster getting an initial fix if within range of a cell phone tower, and may work better inside buildings. Traditional GPS does not need cell phone towers and uses standard GPS signals outside of urban areas. Traditional GPS tends to use more battery power. Almost any digital camera can be coupled with a stand-alone GPS and post processed with photo mapping software, to write the location information to the image's exif header.

{{main|Georeferencing}}

In the field of remote sensing the geotagging goal is to store coordinates of every pixel in the image. One approach is used with the orthophotos where we store coordinates of four corners and all the other pixels can be georeferenced by interpolation. The four corners are stored using GeoTIFF or World file standards. Hyperspectral images take a different approach defining a separate file of the same spatial dimensions as the image where latitude and longitude of each pixel are stored as two 2D layers in so called Input geometry data (IGM) files,{{cite web|title=ENVI Classic Tutorial: Georeferencing Images Using Input Geometry|url=http://www.exelisvis.com/portals/0/pdfs/envi/Georef_Input_Geometry.pdf|publisher=Exelis|access-date=29 April 2015|archive-date=24 May 2015|archive-url=https://web.archive.org/web/20150524080631/http://www.exelisvis.com/portals/0/pdfs/envi/Georef_Input_Geometry.pdf|url-status=dead}} also known as GEO files.

Audio/video files can be geotagged via: metadata, audio encoding, overlay, or with companion files. Metadata records the geospatial data in the encoded video file to be decoded for later analysis. One of the standards used with unmanned aerial vehicle is MISB Standard 0601 which allows geocoding of corner points and horizon lines in individual video frames.MISB Standard 0601 Audio encoding involves a process of converting gps data into audio data such as modem squawk. Overlay involves overlaying GPS data as text on the recorded video. Companion files are separate data files which correspond to respective audio/video files. Companion files are typically found in the .KML and .GPX data formats.{{cite web|url=http://ruggedvid.com/geospatial/|title=Airborne Geospatial Video Recorders, Cameras, and Systems}} For audio and video files which use the vorbiscomment metadata format (including Opus, Ogg Vorbis, FLAC, Speex, and Ogg Theora), there is a proposed GEO LOCATION{{cite web|url=https://wiki.xiph.org/VorbisComment#Geo_Location_fields|title=VorbisComment – XiphWiki|website=wiki.xiph.org}} field which can be used. Like all vorbis comments, it is plain text, and it takes the form:

GEO_LOCATION=(decimal latitude);(decimal longitude);([optional]elevation in meters)

for example:

GEO_LOCATION=35.1592;-98.4422;410

The GeoSMS standard works by embedding one or more 'geo' URIs in the body of an SMS, for example:

:I'm at the pub geo:-37.801631,144.980294;u=16

{{main|LOC record}}

{{further|Internet geolocation}}

RFC 1876 defines a means for expressing location information in the Domain Name System. LOC resources records can specify the latitude, longitude, altitude, precision of the location, and the physical size of on entity attached to an IP address. However, in practice not all IP addresses have such a record, so it is more common to use geolocation services to find the physical location of an IP address.

{{main|ICBM address}}

The GeoURL{{cite web|url=http://geourl.org/add.html |title=Adding yourself to GeoURL |access-date=2008-07-30 |url-status=dead |archive-url=https://web.archive.org/web/20080515145826/http://geourl.org/add.html |archive-date=2008-05-15 }} method requires the ICBM tag{{cite web |url=http://tools.ietf.org/id/draft-daviel-html-geo-tag-08.txt| title=Geographic registration of HTML documents |author=The Internet Engineering Task Force |access-date=2008-07-30}} (plus optional Dublin Core metadata), which is used to geotag standard web pages in HTML format:

The similar Geotag format allows the addition of place name and region tags:

The RDF method is defined by W3 Group and presents the information in RDF tags:{{cite web| url=http://www.w3.org/2003/01/geo/ |title=Basic Geo (WGS84 lat/long) Vocabulary |author=W3C Semantic Web Interest Group |access-date=2008-07-30}}

xmlns:geo="http://www.w3.org/2003/01/geo/wgs84_pos#">

55.701

12.552

The Geo microformat allows coordinates within HyperText Markup Language pages to be marked up in such a way that they can be "discovered" by software tools. Example:

50.167958;

-97.133185

A proposal has been developed{{cite web | title=Geo Extension Straw-Man Proposal | url=http://microformats.org/wiki/geo-extension-strawman | access-date=2007-12-28}} to extend Geo to cover other bodies, such as Mars and the Moon.

An example is the Flickr photo-sharing Web site, which provides geographic data for any geotagged photo in all of the above-mentioned formats.

No industry standards exist, however there are a variety of techniques for adding geographical identification metadata to an information resource. One convention, established by the website Geobloggers and used by more and more sites, e.g. photo sharing sites Panoramio and Flickr, and the social bookmarking site del.icio.us, enables content to be found via a location search. Such sites allow users to add metadata to an information resource via a set of so-called machine tags (see folksonomy).

geotagged

geo:lat=57.64911

geo:lon=10.40744

This describes the geographic coordinates of a particular location in terms of latitude (geo:lat) and longitude (geo:lon). These are expressed in decimal degrees in the WGS84 datum, which has become something of a default geodetic datum with the advent of GPS.{{Citation needed|date=November 2007}}

Using three tags works within the constraint of having tags that can only be single 'words'. Identifying geotagged information resources on sites like Flickr and del.icio.us is done by searching for the 'geotagged' tag, since the tags beginning geo:lat= and geo:lon= are necessarily very variable.

Another option is to tag with a Geohash:

geo:hash=u4pruydqqvj

A further convention proposed by FlickrFly adds tags to specify the suggested viewing angle and range when the geotagged location is viewed in Google Earth:

ge:head=225.00

ge:tilt=45.00

ge:range=560.00

These three tags would indicate that the camera is pointed heading 225° (south west), has a 45° tilt and is 560 metres from the subject.

Where the above methods are in use, their coordinates may differ from those specified by the photo's internal Exif data, for example because of a correction or a difference between the camera's location and the subject's.

In order to integrate geotags in social media and enhance text readability or oral use, the concept of 'meetag' or tag-to-meet has been proposed. Differing from hashtag construction, meetag includes the geolocation information after an underscore. A meetag is therefore a word or an unspaced phrase prefixed with an underscore ("_"). Words in messages on microblogging and social networking services may be tagged by putting "_" before them, either as they appear in a sentence, (e.g. "There is a concert going _montreuxjazzfestival", "the world wide web was invented _cern _geneve", ...) or appended to it.{{cite web |url=http://meet.ag |title=Web page for the 'meetag standard' proposition |url-status=dead |archive-url=https://web.archive.org/web/20140714201304/http://meet.ag/ |archive-date=2014-07-14 }}

Geoblogging attaches specific geographic location information to blog entries via geotags. Searching a list of blogs and pictures tagged using geotag technology allows users to select areas of specific interest to them on interactive maps.{{cite web |url=http://www.everytrail.com/view_trip.php?trip_id=294109 |title=Example of pictures with geotag, using mobile phone |access-date=2009-09-21 |archive-url=https://web.archive.org/web/20150213205127/http://www.everytrail.com/view_trip.php?trip_id=294109 |archive-date=2015-02-13 |url-status=dead }}

The progression of GPS technology, along with the development of various online applications, has fueled the popularity of such tagged blogging, {{Citation needed|date=January 2008}} and the combination of GPS phones and GSM localization, has led to the moblogging, where blog posts are tagged with exact position of the user. Real-time geotagging relays automatically geotagged media such as photos or video to be published and shared immediately.

For better integration and readability of geotags into blog texts, the meetag syntax has been proposed, which transforms any word, sentence, or precise geolocalization coordinates prefixed with an underscore into a 'meetag'. It not only lets one express a precise location but also takes in account dynamically changing geolocations.

{{Cleanup|date=July 2011}}

One of the first attempts to initiate the geotagging aspect of searching and locating articles seems to be the now-inoperative site Wikinear.com, launched in 2008, which showed the user Wikipedia pages that are geographically closest to one's current location.Willison, Simon. (2008). "[http://simonwillison.net/2008/Mar/22/wikinear/ Wininear.com, OAuth and Fire Eagle]", SimonWillison.net, Mar 22 2008

The 2009 app Cyclopedia works relatively well showing geotagged Wikipedia articles located within several miles of ones location, integrated with a street-view mode, and 360-degree mode.

The app Respotter Wiki, launched in 2009, claims to feature Wikipedia searching via a map, also allowing users to interact with people around them, via messaging and reviews, etc. The app, in its current function, however, seems to give only geotagged photo results.

As of 2017, the Wikipedia-World Project provides a simple map search tool which can display tagged articles near to a particular location, as well as a variety of more sophisticated tools integrated with external mapping services.{{cite web |url=https://tools.wmflabs.org/wp-world/karte.php?la=en |title=Geo-link |website=tools.wmflabs.org}}

Following a scientific study{{cite web|url=http://www.usenix.org/events/hotsec10/tech/full_papers/Friedland.pdf |title=G. Friedland, R. Sommer: "Cybercasing the Joint: On the Privacy Implications of Geo-Tagging", 5th Usenix Hot Topics in Security Workshop (HotSec2010), Washington DC, August 2010. |access-date=2013-12-23}} and several demonstrative websites,{{cite web|url=http://www.pleaserobme.com|archive-url=https://web.archive.org/web/20100218220728/http://pleaserobme.com/|url-status=usurped|archive-date=February 18, 2010|title=Please Rob Me|website=www.pleaserobme.com}}{{cite web|url=http://www.icanstalku.com |title=icanstalku.com |publisher=icanstalku.com |access-date=2013-12-23}} a discussion on the privacy implications of geotagging has raised public attention.{{YouTube|N2vARzvWxwY|NBC Action News Smartphone pictures pose privacy risk}}Heussner, Ki Mae, [https://abcnews.go.com/Technology/celebrity-stalking-online-photos-give-location/story?id=11162352 "Celebrities' Photos, Videos May Reveal Location"], ABC News, July 16, 2010[https://www.newscientist.com/article/dn19160-geotags-reveals-celeb-secrets.html Geo-tags reveal celeb secrets], 12 July 2010, by Jim Giles, New Scientist{{cite news|url=https://www.nytimes.com/2010/08/12/technology/personaltech/12basics.html?_r=2 |title=Web Photos That Reveal Secrets Such As Where You Live / "MythBusters" host inadvertently reveals his home address on Twitter |work=The New York Times |date=11 August 2010 |access-date=2013-12-23|last1=Murphy |first1=Kate }} In particular, the automatic embedding of geotags in pictures taken with smartphones is often ignored by cell-phone users. As a result, people are often not aware that the photos they publish on the Internet have been geotagged. Many celebrities reportedly gave away their home location without knowing it.{{citation needed|date=June 2021}} According to the study, a significant number of for-sale advertisements on Craigslist, that were otherwise anonymized, contained geotags, thereby revealing the location of high-valued goods—sometimes in combination with clear hints to the absence of the offerer at certain times. Publishing photos and other media tagged with exact geolocation on the Internet allows random people to track an individual's location and correlate it with other information. Therefore, criminals could find out when homes are empty because their inhabitants posted geotagged and timestamped information both about their home address and their vacation residence. These dangers can be avoided by removing geotags with a metadata removal tool for photos before publishing them on the Internet.{{cn|date=January 2022}}

In 2007, four United States Army Apache helicopters were destroyed on the ground by Iraqi insurgent mortar fire; the insurgents had made use of embedded coordinates in web-published photographs (geotagging) taken of the helicopters by soldiers.{{cite web|url=https://www.army.mil/article/75165/Geotagging_poses_security_risks |title=Geotagging poses security risks |date=8 March 2012 |publisher=Army.mil |access-date=2013-12-23}}

Another newly realized danger of geotagging is the location information provided to criminal gangs and poachers on the whereabouts of often endangered animals. This can effectively make tourists scouts for these poachers, so geotagging should be turned off when photographing these animals.

According to Chinoitezvi Honour, some phones automatically geotag pictures hence location should be turned off when taking pictures.

• Geocaching
• Geographic information system (GIS)
• Georeferencing
• Geomessaging
• GeoRSS
• geo URI scheme
• ISO 6709, standard representation of geographic point location by coordinates
• Tag (metadata)
• Toponym resolution

{{reflist|30em}}

• {{Cite journal|first1=Jiebo|last1=Luo|first2=Dhiraj|last2=Joshi|first3=Jie|last3=Yu|first4=Andrew|last4=Gallagher|title=Geotagging in multimedia and computer vision—a survey|journal=Multimedia Tools and Applications|year=2011 |volume=51|issue=1|pages=187–211|doi=10.1007/s11042-010-0623-y|publisher=Springer|s2cid=7433108 }}

• {{commonscatinline}}

{{Semantic Web}}

{{Web syndication}}

Category:Volunteered geographic information

Category:Geocodes

Category:Global Positioning System