GB342683A - Improvements in or relating to apparatus for use in the production of maps or the like from aerial photographs - Google Patents

Abstract

342,683. Photographic surveying. SOC. ANON. DES USINES GALLUS, 77, Boulevard de la Mission Marchand, Courbevoie, Seine, France. Oct. 30, 1929, No. 32924. Convention date, Nov. 30, 1928. [Class 97 (ii).] In apparatus for use in preparing maps &c. from aerial photographs, in which two photographs of the same tract of country taken from different viewpoints are projected by adjustably mounted projectors on to a screen, the screen is marked with a series of parallel straight lines and the projectors are adjusted so that corresponding rays fall on the same line, thus avoiding the necessity for moving the screen vertically until the said rays intersect on the screen. In the apparatus shown the projectors 1, 2 are mounted so as to be rotatable about their optical axes in members 3 which are pivoted about axes Y, Y<1> in forks 4 which are pivoted about axes O, O<1> in members 5 slidably mounted on tubes 6, 7 rigidly connected together. The tube 6 is supported by a member 8 rotatably mounted in a sleeve 9 which is integral with a sleeve 10 slidably mounted on the member 11 which supports the projection screen E. A number of parallel lines a .. d are marked on the screen so that in using the apparatus it is only necessary to adjust the projectors until the traces m, n of corresponding rays fall on the same line of the series. Adjustment according to the scale of the map to be produced is effected by varying the distance between the projectors and the height of the sleeve 10 on the support 11. Instead of a series of lines, a single line may be used ; this may be marked on the screen which is then made movable in its own plane, or the line may be marked on a separate strip which can be traversed across the screen. For use in apparatus based on stereoscopic vision the apparatus is modified by displacing the projector 2 laterally with respect to the projector 1.