Patent GB-973553-A (GB)
Abstract: 973, 553. Photogrammetric plotting apparatus. E. SANTONI. July 8, 1963 [July 11, 1962], No. 26962/63. Heading G1F. A photogrammetric plotting apparatus includes at least one mounting for a photogram f 1  or f 2 , Fig. 2 and a movable optical viewing system adjacent the mounting the system comprising a support member 27 (Figs. 3 and 7) pivotable about an axis transverse to the mounting and carrying a scanning arm 28 pivotable about an axis parallel to the first axis, the member and the arm enclosing portions of the optical path, and means to project a portion of the image of the particular photogram and a reference indicium forming part of a reticule on a fixed plate 51, Fig. 5, along the optical path, the apparatus also including a pantograph mechanism, Fig. 7, hinged to the member 27 and arm 28 whereby two cam followers 481, 49<SP>1</SP> move in accordance with the movements of the outer end of the scanning arm 28, a pair of face cams urged into contact with each cam follower, one cam of each pair ax, ay being connected to means to effect translational movement in one direction of the mounting, and the other cam of each pair sx, sy being connected to means to effect relative pivotal movement between the mounting and a reticule 65 (Figs. 5 and 9) positioned adjacent the mounting, about an axis substantially parallel with the plane of the mounting, as the scanning arm 28 scans the photogram, to compensate for the systematic and incidental errors in the photogram. Two mountings are provided for photograms f 1 , f 2 , guide rods a,b being universally jointed at points I, II behind the mountings. The rods a, b have joints 1, 2 respectively which are slidable on a carriage 9 in a vertical direction. The carriage 9 is movable in a vertical direction (in this case the X axis) on a further carriage 13 which is in turn slidable on a guide 14 (Y-axis). The guide 14 is itself slidable for movement in the Z-axis. The mountings for the photograms are carried in a cross-bar 10 slidable in the Z-axis and the points I, II are movable in the Z and X axes respectively relative to the cross-bar 10. The photograms are viewed through eyepieces 47 by way of the optical paths shown in Figs. 3 and 5 and including a collimation mark 34 and prisms 29 on the ends of the arms 28. Each mounting consists of a plate 22 supporting a disc 24, the disc being adjustable on the plate by means of a screw 25. The photogram carrier frame 50 is mounted in a square window in the disc 24. The plate 51 carrying the reference indicia is mounted with the photogram f in the frame 50, Fig. 5, and each arm 28 has an extension 28<SP>1</SP> carrying a small lamp in a reflector 28<SP>11</SP> for illumination of the photogram. The arms 28 are each mounted in a pantograph arrangement shown in Fig. 7, whereby as the prism 29 is moved over the photogram the frame 50 is moved to correct for errors under the control of the surface cams ax and ay which are in contact with the cam followers 48<SP>1</SP> and 49<SP>1</SP>. The frame 50 is moved in the X and Y axes relative to the disc 24 by the cam followers 49<SP>1</SP> and 48<SP>1</SP> respectively through the linkages shown in Fig. 7. The surface cams comprise a rigid plate 62 with screws 61 which move a deformable surface carried by the projecting ends of the screws 61. Residual projection errors are detected by the provision of the reticule 65 mounted in gimbals 66, 67 in the disc 24, (Figs. 5 and 9). The reticule 65 is tilted to obtain coincidence between it and the marks on the plate 51, and this tilting is obtained by pivoting of the reticule about its gimbal axes under the control of the surface cams sx and sy, and by way of the linkages shown in Fig. 9. The cams sx and sy are adjusted by using a standard reticule in place of the photogram. The distortions due to the object lens of the camera used may also be provided for by adjustment of cams sx and sy.