Geopositioning, also known as geotracking, geolocalization, geolocating, geolocation, or geoposition fixing, is the process of determining or estimating the geographic position of an object. Geopositioning yields a set of

geographic coordinates The geographic coordinate system (GCS) is a spherical or ellipsoidal coordinate system for measuring and communicating positions directly on the Earth as latitude and longitude. It is the simplest, oldest and most widely used of the various ...

(such as

latitude In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north ...

and

longitude Longitude (, ) is a geographic coordinate that specifies the east– west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek let ...

) in a given map datum; positions may also be expressed as a bearing and range from a known landmark. In turn, positions can determine a meaningful location, such as a street address. Specific instances include:

animal geotracking GPS animal tracking is a process whereby biologists, scientific researchers or conservation agencies can remotely observe relatively fine-scale movement or migratory patterns in a free-ranging wild animal using the Global Positioning System (G ...

, the process of inferring the location of animals; positioning system, the mechanisms for the determination of geographic positions in general;

internet geolocation 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 geogr ...

, geolocating a device connected to the internet; and mobile phone tracking.

Background

Geopositioning uses various visual and electronic methods including

position line A position line or line of position (LOP) is a line (or, on the surface of the earth, a curve) that can be both identified on a chart ( nautical chart or aeronautical chart) and translated to the surface of the earth. The intersection of a minimum ...

s and

position circle A position circle is a circle that can be measured both from a chart and from the surface of the earth for the purpose of position fixing. For the purposes of land or coastal navigation, a position circle can be generated by making a horizontal a ...

celestial navigation Celestial navigation, also known as astronavigation, is the practice of position fixing using stars and other celestial bodies that enables a navigator to accurately determine their actual current physical position in space (or on the surface o ...

radio navigation Radio navigation or radionavigation is the application of radio frequencies to determine a position of an object on the Earth, either the vessel or an obstruction. Like radiolocation, it is a type of radiodetermination. The basic principles a ...

, and the use of

satellite navigation system A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioiso ...

s. The calculation requires measurements or observations of distances or angles to reference points whose positions are known. In 2D surveys, observations of three reference points are enough to compute a position in a

two-dimensional In mathematics, a plane is a Euclidean ( flat), two-dimensional surface that extends indefinitely. A plane is the two-dimensional analogue of a point (zero dimensions), a line (one dimension) and three-dimensional space. Planes can arise as ...

plane. In practice, observations are subject to errors resulting from various physical and atmospheric factors that influence the measurement of distances and angles. A practical example of obtaining a position fix would be for a ship to take bearing measurements on three

lighthouse A lighthouse is a tower, building, or other type of physical structure designed to emit light from a system of lamps and lenses and to serve as a beacon for navigational aid, for maritime pilots at sea or on inland waterways. Lighthouses m ...

s positioned along the coast. These measurements could be made visually using a hand bearing compass, or in poor visibility, electronically using

radar Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, Marine radar, ships, spacecraft, guided missiles, motor v ...

radio direction finding Direction finding (DF), or radio direction finding (RDF), isin accordance with International Telecommunication Union (ITU)defined as radio location that uses the reception of radio waves to determine the direction in which a radio stati ...

. Since all physical observations are subject to errors, the resulting position fix is also subject to inaccuracy. Although in theory two lines of position (LOP) are enough to define a point, in practice 'crossing' more LOPs provides greater accuracy and confidence, especially if the lines cross at a good angle to each other. Three LOPs are considered the minimum for a practical navigational fix. The three LOPs when drawn on the chart will in general form a triangle, known as a 'cocked hat'. The navigator will have more confidence in a position fix that is formed by a small cocked hat with angles close to those of an

equilateral triangle In geometry, an equilateral triangle is a triangle in which all three sides have the same length. In the familiar Euclidean geometry, an equilateral triangle is also equiangular; that is, all three internal angles are also congruent to each oth ...

. The area of doubt surrounding a position fix is called an error ellipse. To minimize the error, electronic navigation systems generally use more than three reference points to compute a position fix to increase the

data redundancy In computer main memory, auxiliary storage and computer buses, data redundancy is the existence of data that is additional to the actual data and permits correction of errors in stored or transmitted data. The additional data can simply be a comple ...

. As more redundant reference points are added, the position fix becomes more accurate and the area of the resulting error ellipse decreases. The process of combining multiple observations to compute a position fix is equivalent to solving a system of

linear equations In mathematics, a linear equation is an equation that may be put in the form a_1x_1+\ldots+a_nx_n+b=0, where x_1,\ldots,x_n are the variables (or unknowns), and b,a_1,\ldots,a_n are the coefficients, which are often real numbers. The coeffici ...

. Navigation systems use regression algorithms such as

least squares The method of least squares is a standard approach in regression analysis to approximate the solution of overdetermined systems (sets of equations in which there are more equations than unknowns) by minimizing the sum of the squares of the re ...

in order to compute a position fix in 3D space. This is most commonly done by combining distance measurements to 4 or more GPS

satellites A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotop ...

, which orbit the earth along known paths. Visual-fix-by-three-bearings

The result of position fixing is called a position fix (PF), or simply a fix, a position derived from measuring in relation to external reference points. In nautical

navigation Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another.Bowditch, 2003:799. The field of navigation includes four general categories: land navigation ...

, the term is generally used with manual or visual techniques, such as the use of intersecting visual or radio

s, rather than the use of more automated and accurate electronic methods like GPS; in aviation, use of electronic navigation aids is more common. A visual fix can be made by using any sighting device with a bearing indicator. Two or more objects of known position are sighted, and the bearings recorded. Bearing lines are then plotted on a chart through the locations of the sighted items. The intersection of these lines is the current position of the vessel. Usually, a fix is where two or more position lines intersect at any given time. If three position lines can be obtained, the resulting "cocked hat", where the three lines do not intersect at the same point, but create a triangle, gives the navigator an indication of the accuracy. The most accurate fixes occur when the position lines are perpendicular to each other. Fixes are a necessary aspect of navigation by

dead reckoning In navigation, dead reckoning is the process of calculating current position of some moving object by using a previously determined position, or fix, and then incorporating estimates of speed, heading direction, and course over elapsed time. ...

, which relies on estimates of

speed In everyday use and in kinematics, the speed (commonly referred to as ''v'') of an object is the magnitude of the change of its position over time or the magnitude of the change of its position per unit of time; it is thus a scalar quant ...

and

course Course may refer to: Directions or navigation * Course (navigation), the path of travel * Course (orienteering), a series of control points visited by orienteers during a competition, marked with red/white flags in the terrain, and corresponding ...

. The fix confirms the actual position during a journey. A fix can introduce inaccuracies if the reference point is not correctly identified or is inaccurately measured.

Usage

WhatsApp WhatsApp (also called WhatsApp Messenger) is an internationally available freeware, cross-platform, centralized instant messaging (IM) and voice-over-IP (VoIP) service owned by American company Meta Platforms (formerly Facebook). It allows use ...

provides a free user location tool which can be used to see the location of a loved one among other uses. Food delivery apps use this. During the

2022 Russian invasion of Ukraine On 24 February 2022, in a major escalation of the Russo-Ukrainian War, which began in 2014. The invasion has resulted in tens of thousands of deaths on both sides. It has caused Europe's largest refugee crisis since World War II. A ...

, the Ukrainian army called airstrikes on locations from videos that have geolocation data. Geopositioning is also used in the collection of

meteorological Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did not ...

and phytopathological data to forecast crop pathogens.

Background

Usage

See also

References

Further reading