A digital theodolite is an instrument for measuring both horizontal and vertical angles, as used in triangulation networks. It is a key tool in surveying and engineering work, but theodolite have been adapted for other specialized purposes in fields like meteorology and rocket launch technology. A modern digital theodolite consists of a telescope mounted movably within two perpendicular axes, the horizontal or trunnion axis, and the vertical axis.
Digital theodolite is mounted on the tripod head by means of a forced centering plate or tribrach, containing four thumbscrews (or in some modern digital theodolite three thumbscrews) for rapid levelling. Prior to Digital theodolite, instruments such as the geometric square and various graduated circles (see circumferentor)
In today's digital theodolite, the reading out of the horizontal and vertical circles is usually done electronically. Digital theodolite or the target can be rapidly removed from, or socketed into, the forced centering plate with sub-mm precision. Accurate electronic digital theodolite have become widespread tools, but transits still find use as a lightweight tool for construction sites. The first instrument more like a true digital theodolite was likely the one built by Joshua Habermel (de:Erasmus Habermehl) in Germany in 1576, complete with compass and tripod.