Definition

In SURVEYING, the procedure of determi­ning the horizontal POSITION of an unoccupied point (INTERSEC­TION STATION) by direction observations from two or more known POSITIONS. In PHOTOGRAMMETRY, the procedure of determining the horizontal POSITION of a point by intersecting lines of direction obtained photogrammetrically. The lines of direction may be obtained directly from VERTICAL PHOTOGRAPHS or by graphic or mathematical rectifica­ti­on of tilted PHOTOGRAPHS.