surveying cognitive and computational treatment of visual perception Gunter's chain theodolite angle proved Euclid distance geometry
As suggested by the etymology of the word, one of the earliest reasons for interest in and also one of the most common current use of geometry is surveying. In addition it has been used in the cognitive and computational treatment of visual perception, also certain practical results from Euclidean geometry (such as the right-angle property of the 3-4-5 triangle) were used long before they were proved formally. The fundamental types of measurements in Euclidean geometry are distances and angles, both of which can be measured directly by a surveyor. Historically, distances were often measured by chains, such as Gunter's chain, and angles using graduated circles and, later, the theodolite.
