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Triangulation can also refer to the accurate surveying of systems of very large triangles, called triangulation networks. This followed from the work of Willebrord Snell in 1615–17, who showed how a point could be located from the angles subtended from three known points, but measured at the new unknown point rather than the previously fixed ...
In cartography, a triangulated irregular network is a point set triangulation of a set of two-dimensional points together with elevations for each point. Lifting each point from the plane to its elevated height lifts the triangles of the triangulation into three-dimensional surfaces, which form an approximation of a three-dimensional landform.
Triangulation today is used for many purposes, including surveying, navigation, metrology, astrometry, binocular vision, model rocketry and, in the military, the gun direction, the trajectory and distribution of fire power of weapons. The use of triangles to estimate distances dates to antiquity.
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.
Practically unused in cartography because of severe polar distortion, but popular in panoramic photography, especially for architectural scenes. c. 1600: Sinusoidal = Sanson–Flamsteed = Mercator equal-area: Pseudocylindrical Equal-area, equidistant (Several; first is unknown) Meridians are sinusoids; parallels are equally spaced.
Example of triangle network and its application in cartography Main article: Georeferencing After a cartographer registers key points in a digital map to the real world coordinates of those points on the ground, the map is then said to be "in control".
The Ordnance Survey's original maps were made by triangulation. For the second survey, in 1934, this process was used again and resulted in the building of many triangulation pillars (trig points): short (c. 4 feet/1.2 m high), usually square, concrete or stone pillars at prominent locations such as hill tops. Their precise locations were ...
In 1783 the French Academy of Science presented his proposal to King George III. [7] This connection and a proposal from General William Roy led to the first triangulation of Great Britain. [ 7 ] France and Great Britain surveys' connection was repeated by French astronomers and geodesists in 1787 by Cassini IV , in 1823–1825 by François ...