Patent GB-355443-A (GB)
Title: Improvements in and relating to apparatus for producing maps from photographs
IPC: G01C11/00
Filed: 1930-07-08
Abstract: 355,443. Photographic surveying- apparatus. NISTRI, U., 11, Via Francesco Negri, Rome. July 8, 1930. No. 20722. Convention date, July 27, 1929. [Classes 97 (ii) and 97 (iii).] Apparatus for drawing a map of ground represented by two photographs comprises a projector group including two optical projectors capable of assuming any position and orientation in space and a reconstruction group including a principal movable screen for reception of the image, independently movable auxiliary screens for indicating the relative positions of three or more points on the ground whose positions are known and means for transferring the image of the ground graphically on to a drawing sheet. In use the two projectors are adjusted so that the images of the known points coincide with the auxiliary screens indicating their relative positions in the reconstruction group. In the form shown, the projector group, Fig. 1, comprises two vertical columns 1 (only one shown) along which two carriages 3 can be adjusted by rack and pinion operated by the handles 4, 5. Each carriage 3 carries guides 7 in which travels a carriage 8 controlled by the hand-wheel 9, whilst a further carriage 12 is movable along guides 10, on the carriages 8 at right-angles to the guides 7 by the hand-wheel 11. A casing A carrying an optical projection system has at one end a rotatable sleeve which is pivoted in a fork 18 rotatably mounted on the carriage 12, the centre of rotation of the casing coinciding with the optical centre of the object lens. An axially slidable pivot 62 mounted in the other end of the casing A is pivoted to a nut 62a engaging with a screw 19 mounted in a fork 23 which is rotatably mounted in the carriage 12. By turning the handle 26 the screw 19 can be rotated, thus moving the nut 62a. A handwheel 24 is adapted to turn the fork 23 about its pivotal axis and a further hand-wheel 20 mounted on a sleeve on the pivot 62 turns the casing A about its own axis. The two projectors may thus be moved to any position and pointed in any direction. The apparatus for receiving the projected images and for constructing a map therefrom comprises two vertical columns 30, Figs. 3 and 5, carrying screens 36 which may be adjusted to represent to a chosen scale the positions of points on the ground, the co-ordinates of which are known. The drawing system comprises a bed 37 normal to the image plane and capable of being moved towards or away from it by the hand-wheels 40 which control a screw 41 acting on a nut fixed in the support 42. A carriage 45 travels on rails 44 on the bed 37 and is moved parallel to the image plane by means of a screw 52 mounted in the plates 53. The carriage 45 is provided with a vertical rod 48 upon which a squared screen 49 is caused to move by the screw 54. A further carriage 47 is caused to move on rails 46 on the bed 37 by a screw 56 and supports a pencil-carrying member 51 which is movable in a direction normal to the image plane by a screw 50. The screws 52, 54, 56, 50 may be geared together in pairs at will so that the pencil-carrying member 51 may be made to repeat the movements of the screen 49 thus tracing a map to any desired scale as the screen 49 traverses. the features of the projected image. Contour lines may be traced by displacing the bed 37 and running the screen 49 over the positions of coincidence of the two projected images. Profiles of the ground may be traced by gearing one of the screws moving the member 51 to the screw 41 moving the bed 37 and the other to one of the screws moving the screen 49. Specification 182,912, [Class 97 (ii), Surveying &c. instruments], is referred to.