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Basic Principle |
| A theodolite is an optical instrument used for measuring angles, by measuring differences in directions, in the horizontal and vertical planes. A theodolite is referenced to the vertical, as defined by gravity, by levelling the instrument using bubbles or tilt sensors. Line of sight directions are observed using a telescope and cross hair, and optically or electronically read from horizontal and vertical circles that are analogous to very finely and accurately divided protractors. All theodolites have similar constructional features regardless of their age or level of technology, and all perform basically the same functions. |
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