A triangulation station, also known as a trigonometrical point, and sometimes informally as a trig, is a fixed surveying station, used in geodetic surveying and other surveying projects in its vicinity. The nomenclature varies regionally: they are generally known as trigonometrical stations or triangulation stations in North America, trig points in the United Kingdom, trig pillars in Ireland, trig stations or trig points in Australia and New Zealand, and trig beacons in South Africa.
A trigonometrical station in Sunset Peak, Hong Kong
Trigonometrical station, NSW, Australia.
Trig point atop Mount Wellington, Tasmania
A trigonometrical station in Chek Lap Kok Scenic Hill, Hong Kong
Surveying or land surveying is the technique, profession, art, and science of determining the terrestrial two-dimensional or three-dimensional positions of points and the distances and angles between them. These points are usually on the surface of the Earth, and they are often used to establish maps and boundaries for ownership, locations, such as the designed positions of structural components for construction or the surface location of subsurface features, or other purposes required by government or civil law, such as property sales.
A surveyor using a total station
A student using a theodolite in field
Table of Surveying, 1728 Cyclopaedia
A railroad surveying party at Russel's Tank, Arizona in the 1860s