Abstract: An apparatus for use in photogrammetry is disclosed having two spaced-apart parallel scanning zones to which the photographs of a stereoscopic pair of photographs are mounted.A carriage mounted optical scanning system is provided for scanning the two scanning zones and for projecting images of the respective zones to a binocular viewing system, and a secondary optical system is provided, preferably on the carriage, for superimposing reference marks on the projected images.The scanning system is arranged in such a manner that simultaneous scanning of the two scanning zones can be effected in a first direction parallel to the scanning zones, and independent scanning of the two scanning zones can be effected in a second direction which is parallel to the scanning zones and orthogonal to the first direction. Also, the apparatus is adapted to permit relative scanning of the two scanning zones in the first direction or for optically moving the reference marks relative to one another in the first direction.