A trig point near Wootton Wawen. Warwickshire

Trig points are triangulation pillars. In the UK they were erected by the Ordnance Survey. Image File history File links Download high resolution version (1296x972, 505 KB)Trig point near Wootton Wawen Warwickshire Author: User:Velela. ... Image File history File links Download high resolution version (1296x972, 505 KB)Trig point near Wootton Wawen Warwickshire Author: User:Velela. ... Wootton Wawen is a small village and civil parish in the Stratford district of Warwickshire, England. ... Warwickshire (pronounced either /ˈwɔːɹɪkˌʃə/ or /ˈwɔːɹɪkˌʃɪə/) is a landlocked non-metropolitan county in central England. ... Triangulation can be used to find the distance from the shore to the ship. ... Image produced from the Ordnance Survey Get-a-map service. ...

The process of placing trig points on top of prominent hills and mountains began in 1935 to assist in the accurate re-mapping of Great Britain by triangulation directed by the cartographer and mathematician Martin Hotine. In low lying or flat areas some trig points may be only a few metres above sea-level. When all the trig points were in place, it was possible, in clear weather, to see at least two other trig points from any one trig point. Careful measurements of the angles between the lines-of-sight of the other trig points then allowed the construction of a system of triangles which could then be referenced back to a single baseline to construct a highly accurate measurement system that covered the entire country. á 1935 (MCMXXXV) was a common year starting on Tuesday (link will take you to calendar). ...

An Australian trig point

A benchmark on a trig point in north Wales

Trig points are truncated square concrete pyramids or obelisks tapering towards the top. On the top a brass plate with three arms and a central depression is fixed. A plaque on the side provides the reference number of the trig point and the letters O S B M ("Ordnance Survey Bench Mark"). Within the trig point, there are concealed mountings for a specialized theodolite, which was temporarily mounted on the trig point while measurements were taken. Image File history File links Download high resolution version (718x898, 58 KB)Davidson Trig point on Red Hill, Australian Capital Territory. ... Image File history File links Download high resolution version (718x898, 58 KB)Davidson Trig point on Red Hill, Australian Capital Territory. ... Image File history File links Benchmark. ... Image File history File links Benchmark. ... This is about the polyhedron. ... For the obelisk punctuation mark, see dagger (typography). ... Diagram of an Optical Theodolite. ...

A national geodetic survey and adjustment carried out in the early 1970s in Australia has left a legacy of trig stations consisting of a ground mark with a white quadripod supporting a black disc above the ground mark. These trig stations are clearly visible for many kilometres and useful for hikers.

In the UK many trig points are now disappearing from the countryside as they no longer have a function since aerial photography and digital mapping using lasers and GPS co-ordinates has taken over. Aerial photography is the taking of photographs from above with a camera mounted on an aircraft, balloon, rocket, kite or similar vehicle. ... The range of sizes in which lasers exist is immense, extending from microscopic diode lasers (top) to football field sized neodymium glass lasers (bottom) used for inertial confinement fusion. ... Over fifty GPS satellites such as this NAVSTAR have been launched since 1978. ...

Benchmarks have a similar purpose in providing a definitive height reference for mapping purposes. An Ordnance Survey benchmark A C&GS benchmark disk Typical C&GS triangulation station A benchmark is a point of reference for a measurement. ...

Trigpointing is a 'sport' which has grown for people to individually go out, find and log finding of trig points. Trigpointing is a sport which has grown for people to individually go out, find and log finding of trig points. ...

See also

• Ordnance Survey
• Retriangulation of Great Britain

Image produced from the Ordnance Survey Get-a-map service. ... In 1935, the new Director General of the Ordnance Survey, Major-General Malcolm MacLeod, started the retriangulation of Great Britain, an immense task which involved erecting concrete triangulation pillars (trig points) on prominent hilltops throughout Great Britain. ...

External links

• UK Benchmarking
• Trigpointing UK
• United Kingdom trig points