Geolocation is the identification of the real-world geographic location of an object, such as a radar source, mobile phone or Internet-connected computer terminal. Geolocation may refer to the practice of assessing the location, or to the actual assessed location. Geolocation is closely related to the use of positioning systems but may be distinguished from it by a greater emphasis on determining a meaningful location (e.g. a street address) rather than just a set of geographic coordinates.
For either geolocating or positioning, the locating engine often uses radio frequency (RF) location methods, for example Time Difference Of Arrival (TDOA) for precision. TDOA systems often utilise mapping displays or other geographic information system. When a GPS signal is unavailable, geolocation applications can use information from cell towers to triangulate the approximate position, a method that is not as accurate as GPS but has greatly improved in recent years. This is in contrast to earlier radiolocation technologies, for example Direction Finding where a line of bearing to a transmitter is achieved as part of the process.
Internet and computer geolocation can be performed by associating a geographic location with the Internet Protocol (IP) address, MAC address, RFID, hardware embedded article/production number, embedded software number (such as UUID, Exif/IPTC/XMP or modern steganography), invoice, Wi-Fi positioning system, device fingerprint, canvas fingerprinting or device GPS coordinates, or other, perhaps self-disclosed information. Geolocation usually works by automatically looking up an IP address on a WHOIS service and retrieving the registrant's physical address.
IP address location data can include information such as country, region, city, postal/zip code,〔(【引用サイトリンク】title=Digital Element Finding Demand for Granular IP Targeting )〕 latitude, longitude and timezone. Deeper data sets can determine other parameters such as domain name, connection speed, ISP, language, proxies, company name, US DMA/MSA, NAICS codes, and home/business.
At times geolocation can be more deductive, as with crowdsourcing efforts to determine the position of videos of training camps, combats, and beheadings in Syria by comparing features detected in the video with publicly available map databases such as Google Earth, as practiced by sites such as Bellingcat.〔(【引用サイトリンク】title=Crowd-Funded Journalists Geo-Locate ISIS Training Camp Using the Militants’ Own Photos )〕
The word ''geolocation'' is also the latitude and longitude coordinates of a particular location. Term and definition standardized by ISO/IEC 19762-5:2008.
In the field of animal biology and ecology, the word ''geolocation'' is also used to refer to the process of inferring the location of a tracked animal based, for instance, on the time history of sunlight brightness or the water temperature and depth measured by an instrument attached to the animal. Such instruments are commonly called archival tags (including microchip implants, Pop-up satellite archival tags, and data storage tags) or dataloggers.
Some standards and name servers include: ISO 3166, FIPS, INSEE, Geonames, IATA and ICAO. For geographic locations in the United States, the American National Standards Institute (ANSI) Codes are often used. ANSI INCITS 446-2008 is entitled "Identifying Attributes for Named Physical and Cultural Geographic Features (Except Roads and Highways) of the United States, Its Territories, Outlying Areas, and Freely Associated Areas, and the Waters of the Same to the Limit of the Twelve-Mile Statutory Zone".〔
A number of commercial solutions have been proposed:
* WOEID (Where on Earth IDentifier) is a unique 32-bit reference identifier that identifies any feature on Earth.〔
* NAC Locator provides a universal geocoding address for all locations on the planet.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』