Plane table

A surveying instrument consisting of a drawing board mounted on a tripod, used to plot observations directly in the field. Its orientation and sighting device let surveyors draw map details as they measure them.

Alidade: A sighting instrument used to measure directions or draw lines toward visible points. The alidade sights landmarks and transfers their directions onto the drawing board.
Topographic map: A map showing terrain relief and natural or human-made features at a stated scale. Plane-table work produces field maps that can represent terrain and visible features.
Topographic surveying: Surveying that records terrain elevations and natural and constructed features for mapping. Plane tables were used to map ground form and visible details in the field.
Theodolite: A surveying instrument that measures horizontal and vertical angles precisely. Unlike a plane table, a theodolite measures angles without directly drawing the map.
Resection (surveying): A surveying method that locates an unknown position by observing directions to known points. Resection can establish the plane table’s position by aligning sights to mapped landmarks.
Map scale: The relationship between distances on a map and corresponding distances on the ground. A chosen scale determines how measured field distances fit on the drawing sheet.
Cadastral surveying: Surveying that establishes and documents property boundaries and land parcels. Plane-table methods have been used to plot parcel boundaries and land features.
Total station: An electronic surveying instrument combining a theodolite with distance measurement and digital data storage. A total station records numerical observations electronically instead of plotting them on a board.
Traversing: A surveying method that determines positions through a sequence of connected measured lines. A plane table can plot a traverse directly as its stations and directions are observed.
Surveying: The measurement and representation of positions, distances, angles, and land features. Plane tables are instruments within the broader practice of surveying.

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