Stereograph
a general-purpose stereophotogrammetric device for mechanical projection with transformed bundles of rays. Stereographs are used for making topographical maps from aerial photographs with angles of inclination up to 3°. The principle of the stereograph was proposed by the Soviet scientist F. V. Dro-byshev in the early 1950’s; the abbreviation for the device is SD (stereograph of Drobyshev).
Figure 1 illustrates the principle of the stereograph. The aerial photographs (1) are always positioned horizontally regardless of their angles of inclination. The effect of the angles of inclination is compensated by correction mechanisms, consisting of the correction planes (2) along which the followers (3) move. The followers in turn displace the carriages (4) connected to the universal joints (5). Through these joints, the projecting arms (6) link the photographs to the coordinate measuring device equipped with guide bars (X, Y, and Z). A base device containing mechanisms for introducing the base components (bx, by, and bz), which constitute the base of the projection, is moved along by the carriage (Z). When the carriages of the coordinate measuring device move, the projecting arms, rotating around the centers of projection (7), simultaneously move the photographs and the followers along inclined (depending on the angles of inclination of the aerial photographs) correction planes. As a result of this movement, the position of the universal joints (5) undergoes a change, and the photographs receive additional displacements (the effect of the angles of inclination being eliminated).
P. S. ALEKSANDROV