Geopositioning

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. Specific instances include: animal geotracking, 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. Geopositioning uses various visual and electronic methods including position lines and position circles, celestial navigation, 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 lighthouses 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. 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.