point de visée avant

OBS: point de visée. [...] la lunette [d'un théodolite] peut être dirigée à volonté sur un point de visée [...]

CONT: For angle measuring or line prolongation, the foresight is the angle measurement on the graduated horizontal circle of the instrument (set or to be read and recorded) when the vertical cross hair of the instrument is visually coinciding with the foresight point or with a marker in the vertical plane through the foresight point and the center of the instrument.