Surveying
If the horizontal distance between the staff point and the point of observation is d, then the error due to curvature of earth is proportional to

d2
1/d
1/d2
d

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Surveying
For mapping any country

Geodetic triangulation of greatest possible sides and accuracy is carried out
All listed here
Secondary triangles are further broken into third and fourth order triangles, the points of which are used for detail surveys
Primary triangles are broken down into secondary triangles of somewhat lesser accuracy

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