Geotagging

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Geotag information in a JPEG photo, shown by the software gThumb Geotagging gThumb.png
Geotag information in a JPEG photo, shown by the software gThumb
Geotag information stamped onto a JPEG photo by the software GPStamper Geotag Stamp.jpg
Geotag information stamped onto a JPEG photo by the software GPStamper
Geotagger "Solmeta N2" for the Nikon D5000 DSLR Solmeta N2 auf Nikon D5000 Rueckansicht.JPG
Geotagger "Solmeta N2" for the Nikon D5000 DSLR

Geotagging , or GeoTagging, is the process of adding geographical identification metadata to various media such as a geotagged photograph or video, websites, SMS messages, QR Codes or RgSS feeds and is a form of geospatial metadata. This data usually consists of latitude and longitude coordinates, though they can also include altitude, bearing, distance, accuracy data, and place names, and perhaps a time stamp.

Contents

Geotagging can help users find a wide variety of location-specific information from a device. For instance, someone can find images taken near a given location by entering latitude and longitude coordinates into a suitable image search engine. Geotagging-enabled information services can also potentially be used to find location-based news, websites, or other resources. [1] Geotagging can tell users the location of the content of a given picture or other media or the point of view, and conversely on some media platforms show media relevant to a given location.

The geographical location data used in geotagging can, in almost every case, be derived from the global positioning system, and based on a latitude/longitude-coordinate system that presents each location on the earth from 180° west through 180° east along the Equator and 90° north through 90° south along the prime meridian.[ citation needed ]

The related term geocoding refers to the process of taking non-coordinate-based geographical identifiers, such as a street address, and finding associated geographic coordinates (or vice versa for reverse geocoding). Such techniques can be used together with geotagging to provide alternative search techniques.[ citation needed ]

Applications

In social media

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. [2]

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.

Photos

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, [3] 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. [4]

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.

Remote sensing data

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, [5] also known as GEO files.

Audio/video 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. [6] 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. [7] 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 [8] 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

SMS messages

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

DNS entries

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.

HTML pages

ICBM method

The GeoURL [9] method requires the ICBM tag [10] (plus optional Dublin Core metadata), which is used to geotag standard web pages in HTML format:

<metaname="ICBM"content="50.167958, -97.133185">

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

<metaname="geo.position"content="50.167958;-97.133185"><metaname="geo.placename"content="Rockwood Rural Municipality, Manitoba, Canada"><metaname="geo.region"content="ca-mb">

RDF feeds

The RDF method is defined by W3 Group and presents the information in RDF tags: [11] 

<rdf:RDFxmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"xmlns:geo="http://www.w3.org/2003/01/geo/wgs84_pos#"><geo:Point><geo:lat>55.701</geo:lat><geo:long>12.552</geo:long></geo:Point></rdf:RDF>

Microformat

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:

<spanclass="geo"><spanclass="latitude">50.167958</span>;     <spanclass="longitude">-97.133185</span></span>

A proposal has been developed [12] 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.

In tag-based systems

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 ]

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=225.00ge:tilt=45.00ge: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. [13]

Geoblogging

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. [14]

The progression of GPS technology, along with the development of various online applications, has fueled the popularity of such tagged blogging, [ citation needed ] 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.

Wikipedia article geosearching apps

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. [15]

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. [16]

Dangers

Following a scientific study [17] and several demonstrative websites, [18] [19] a discussion on the privacy implications of geotagging has raised public attention. [20] [21] [22] [23] 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 ] 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.[ citation needed ]

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. [24]

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.

See also

Related Research Articles

<span class="mw-page-title-main">Exif</span> Metadata standard in digital images

Exchangeable image file format is a standard that specifies formats for images, sound, and ancillary tags used by digital cameras, scanners and other systems handling image and sound files recorded by digital cameras. The specification uses the following existing encoding formats with the addition of specific metadata tags: JPEG lossy coding for compressed image files, TIFF Rev. 6.0 for uncompressed image files, and RIFF WAV for audio files. It does not support JPEG 2000 or GIF encoded images.

GPS Exchange Format (GPX) is an XML schema designed as a common GPS data format for software applications. It can be used to describe waypoints, tracks, and routes. It is an open format and can be used without the need to pay license fees. Location data is stored in tags and can be interchanged between GPS devices and software. Common software applications for the data include viewing tracks projected onto various map sources, annotating maps, and geotagging photographs based on the time they were taken.

In computing, Internet geolocation is software capable of deducing the geographic position of a device connected to the Internet. For example, the device's IP address can be used to determine the country, city, or ZIP code, determining its geographical location. Other methods include examination of Wi-Fi hotspots, a MAC address, image metadata, or credit card information.

<span class="mw-page-title-main">Geotagged photograph</span> Photograph associated with a geographical location

A geotagged photograph is a photograph which is associated with a geographic position by geotagging. Usually this is done by assigning at least a latitude and longitude to the image, and optionally elevation, compass bearing and other fields may also be included.

<span class="mw-page-title-main">Image sharing</span> Publishing or transfer of photos online

Image sharing, or photo sharing, is the publishing or transfer of digital photos online. Image sharing websites offer services such as uploading, hosting, managing and sharing of photos. This function is provided through both websites and applications that facilitate the upload and display of images. The term can also be loosely applied to the use of online photo galleries that are set up and managed by individual users, including photoblogs. Sharing means that other users can view but not necessarily download images, and users can select different copyright options for their images.

The Extensible Metadata Platform (XMP) is an ISO standard, originally created by Adobe Systems Inc., for the creation, processing and interchange of standardized and custom metadata for digital documents and data sets.

Microformats (μF) are a set of defined HTML classes created to serve as consistent and descriptive metadata about an element, designating it as representing a certain type of data. They allow software to process the information reliably by having set classes refer to a specific type of data rather than being arbitrary.

<span class="mw-page-title-main">Point of interest</span>

A point of interest (POI) is a specific point location that someone may find useful or interesting. An example is a point on the Earth representing the location of the Eiffel Tower, or a point on Mars representing the location of its highest mountain, Olympus Mons. Most consumers use the term when referring to hotels, campsites, fuel stations or any other categories used in modern automotive navigation systems.

Geo is a microformat used for marking up geographical coordinates in HTML. Coordinates are expected in angular units of degrees and geodetic datum WGS84. Although termed a "draft" specification, the format is a de facto standard, stable and in widespread use; not least as a sub-set of the published hCalendar and hCard microformat specifications, neither of which is still a draft.

<span class="mw-page-title-main">Geosocial networking</span> Social network with geographic features

Geosocial networking is a type of social networking in which geographic services and capabilities such as geocoding and geotagging are used to enable additional social dynamics. User-submitted location data or geolocation techniques can allow social networks to connect and coordinate users with local people or events that match their interests. Geolocation on web-based social network services can be IP-based or use hotspot trilateration. For mobile social networks, texted location information or mobile phone tracking can enable location-based services to enrich social networking.

MapWith.Us is a geosocial networking website that allows users to create and share custom maps with an online community. User maps are created by uploading and geotagging media. When media is associated with a location on a map, the media is known as a map article. Map articles may include text, photos, paths, icons, video, web links, and RSS feeds.

Real-time geotagging refers to the automatic technique of acquiring media, associating a specific location with the media, transferring the media to an online map and publishing the media in real time. It is thus an extension of an automatic geotagging process, requiring an in-built or attached location acquisition device, but also requires communication with a wireless data transfer device. Most modern smartphones and several digital cameras already integrate camera, aGPS, and wireless data transfer into one device, thus directly producing a geotagged photograph. Real-time geotagging is sometimes referred to as "mobile geotagging" or "autogeotagging", but this does not imply the real-time publishing step.

The Ricoh 500SE digital compact camera is suitable for outdoor photography and networkability. Capability includes external information such as GPS position or barcode numbers within the image headers. External vendors sell hardware and software for workflows involving GPS positioning or barcode scanning. Most NMEA compliant Bluetooth GPS receivers can be used with this camera through its built in Bluetooth communication capability. The body is resistant to dust and water, making it robust for many environments.

The W3C Geolocation API is an effort by the World Wide Web Consortium (W3C) to standardize an interface to retrieve the geographical location information for a client-side device. It defines a set of objects, ECMAScript standard compliant, that executing in the client application give the client's device location through the consulting of Location Information Servers, which are transparent for the application programming interface (API). The most common sources of location information are IP address, Wi-Fi and Bluetooth MAC address, radio-frequency identification (RFID), Wi-Fi connection location, or device Global Positioning System (GPS) and GSM/CDMA cell IDs. The location is returned with a given accuracy depending on the best location information source available.

GeoSMS is a specification for geotagging SMS messages. It works by embedding locations in the message text, where the locations are formatted as 'geo' URIs as defined in RFC 5870.

<span class="mw-page-title-main">Red Hen Systems</span>

Red Hen Systems, Inc. is a technology company that develops integrated hardware and software for multimedia asset mapping. Their spatial digital video recorders (DVRs) and still cameras instantly geotag video and still photos at the time of data collection. Corresponding mapping software provides the capability to view photographs, video, and audio using GPS coordinates.

GeoReader is a landmark locating software application and website for mobile iPhone and Android based devices. Users travel into the vicinity of a "talking point", and the software enables the phone to read text aloud that is linked with a GPS location. In addition, users can create their own 200 character count text to add to the database, and choose to share these talking points publicly or privately. The system is hands free and requires no physical interaction. Once the app is installed in the mobile device, the user simply opens the app and starts their trip. The application automatically then starts to search for any GPS tagged talking points within range of the user.

In geographic information systems, toponym resolution is the relationship process between a toponym, i.e. the mention of a place, and an unambiguous spatial footprint of the same place.

Geomessaging is a technology that allows a person or system to send a message based on any media to a device that enters or exits one or more regions. Those regions can be created by using geofences, based on Latitude and Longitude, or adding beacons to the system associating those beacons with named locations. The device will receive the message according to the rules defined by the campaign administrator.

<span class="mw-page-title-main">Geopositioning</span> Identification of the real-world geographic position of an object

Geopositioning is the process of determining or estimating the geographic position of an object or a person.

References

  1. ↑ "GPS adds dimension to online photos". The Oklahoman . Oklahoma City, OK. Associated Press. 22 January 2008. Archived from the original on 24 September 2021. Retrieved 21 September 2020.
  2. ↑ "Facebook's New Mobile Feature For Finding People Around You". 24 June 2012. Retrieved 2016-04-19.
  3. ↑ "Wireless 911 Services" . Retrieved 2010-07-15.
  4. ↑ "Photographers Have Several Camera Options for Geotagging Pictures with GPS Points". Archived from the original on 2018-06-23. Retrieved 2018-06-23.
  5. ↑ "ENVI Classic Tutorial: Georeferencing Images Using Input Geometry" (PDF). Exelis. Archived from the original (PDF) on 24 May 2015. Retrieved 29 April 2015.
  6. ↑ MISB Standard 0601
  7. ↑ "Airborne Geospatial Video Recorders, Cameras, and Systems".
  8. ↑ "VorbisComment – XiphWiki". wiki.xiph.org.
  9. ↑ "Adding yourself to GeoURL". Archived from the original on 2008-05-15. Retrieved 2008-07-30.
  10. ↑ The Internet Engineering Task Force. "Geographic registration of HTML documents" . Retrieved 2008-07-30.
  11. ↑ W3C Semantic Web Interest Group. "Basic Geo (WGS84 lat/long) Vocabulary" . Retrieved 2008-07-30.{{cite web}}: CS1 maint: numeric names: authors list (link)
  12. ↑ "Geo Extension Straw-Man Proposal" . Retrieved 2007-12-28.
  13. ↑ "Web page for the 'meetag standard' proposition". Archived from the original on 2014-07-14.
  14. ↑ "Example of pictures with geotag, using mobile phone". Archived from the original on 2015-02-13. Retrieved 2009-09-21.
  15. ↑ Willison, Simon. (2008). "Wininear.com, OAuth and Fire Eagle", SimonWillison.net, Mar 22 2008
  16. ↑ "Geo-link". tools.wmflabs.org.
  17. ↑ "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" (PDF). Retrieved 2013-12-23.
  18. ↑ "Please Rob Me". www.pleaserobme.com.
  19. ↑ "icanstalku.com". icanstalku.com. Retrieved 2013-12-23.
  20. ↑ NBC Action News Smartphone pictures pose privacy risk on YouTube
  21. ↑ Heussner, Ki Mae, "Celebrities' Photos, Videos May Reveal Location", ABC News, July 16, 2010
  22. ↑ Geo-tags reveal celeb secrets, 12 July 2010, by Jim Giles, New Scientist
  23. ↑ Murphy, Kate (11 August 2010). "Web Photos That Reveal Secrets Such As Where You Live / "MythBusters" host inadvertently reveals his home address on Twitter". The New York Times . Retrieved 2013-12-23.
  24. ↑ "Geotagging poses security risks". Army.mil. 8 March 2012. Retrieved 2013-12-23.

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