Geopositioning
Geopositioning is the process of determining or estimating the
Geopositioning yields a set of
Specific instances include:
Background
Geopositioning uses various visual and
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
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 case of 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.[4] 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 process of combining multiple observations to compute a position fix is equivalent to solving a system of
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.
See also
- Direction determination
- Dynamic positioning
- Geo-blocking
- Geocoding
- GPS tracking unit
- Geotagging
- Geotargeting
- Indoor positioning
- Latitude determination
- Longitude determination
- Location-based service
- Satellite navigation software
- Triangulation
- Vertical position measurement
- W3C Geolocation API
References
- ISO/TC 211Geolexica. 2020-06-02. Retrieved 2020-08-31.
- ^ Keating, J.B.; United States. Bureau of Land Management (1993). The Geo-Positioning Selection Guide for Resource Management. BLM technical note. Bureau of Land Management. p. 5. Retrieved 2020-08-31.
- ISBN 978-3-7091-6078-7.
- ISBN 978-1-4614-1836-8. Retrieved 2020-08-31.
- ISBN 978-1-4419-7952-0. Retrieved 2020-08-31.
- ISBN 978-1-118-74368-3. Retrieved 2020-08-31.
- ISBN 978-1-136-40725-3.
- ISBN 978-3-319-25781-5. Retrieved 2020-08-31.
Further reading
- Zekavat, R.; Buehrer, R.M. (2019). Handbook of Position Location: Theory, Practice, and Advances. IEEE Series on Digital & Mobile Communication. Wiley. ]
- Munoz, D.; Lara, F.B.; Vargas, C.; Enriquez-Caldera, R. (2009). Position Location Techniques and Applications. Elsevier Science. ISBN 978-0-08-092193-8. Retrieved 2021-02-19.
External links
- Media related to Geolocation at Wikimedia Commons