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 (such as latitude and longitude) 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 An address is a collection of information, presented in a mostly fixed format, used to give the location of a building, apartment, or other structure or a plot of land, generally using political boundaries and street names as references, along ...

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

Background

Geopositioning uses various visual and electronic methods including position lines 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 ang ...

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 of ...

, radio navigation, and the use of satellite navigation systems. 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 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 mar ...

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

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 station ...

. 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. 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 compl ...

. 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 coefficien ...

. 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 res ...

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

GPS The Global Positioning System (GPS), originally Navstar GPS, is a Radionavigation-satellite service, satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of t ...

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, the term is generally used with manual or visual techniques, such as the use of intersecting visual or radio position lines, rather than the use of more automated and accurate electronic methods like

; 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, which relies on estimates of speed 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 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. An ...

, 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