Patent GB-630066-A (GB)
Title: Improvements in stereogrammetric apparatus
IPC: G01C11/00
Filed: 1947-02-21
Abstract: 630,066. Stereogrammetric apparatus. GRONDONA, V. D. Feb. 21, 1947, No. 15095/45. [Class 97 (i)] Apparatus for plotting contours and maps from a pair of photostereograms comprises a carriage movable in two perpendicular directions and bearing the photograms, and a binocular stereoscopic optical system, one of the objectives of which is movable to compensate the parallax between the images observed by each eye and to bring them into a standard part of the stereoscopic field of view, the movements of the objective and of the carriage being so coupled to a pantographic plotting device that the latter is moved according to the range and azimuth of the observed image, at different elevations. The point of origin of the plotting radius vector normally corresponds to the objective of the camera on the left during photography but may correspond to any point on the base line between the two cameras. As shown in Fig. 1, the carriage a bearing photograms 1, 2 in adjustable carriers 93, 94 is movable laterally along rails 3 for azimuth variations, the rails 3 forming with bars 4, 5 a framework h movable longitudinally on rollers 6, 7 for elevation adjustment. Lateral movement is effected by a rod 9 engaging a slot 8 and carried by a cursor 10 threaded to a shaft 12, while longitudinal movement is effected by a cursor 22 and block 22<SP>1 </SP>movable by screw 23 on a carriage i and slidably engaging an arm 20<SP>1</SP> on a pivoted shaft 15 also carrying an arm 20<SP>11</SP> engaging the framework h at 19. The binocular system comprises systems f, g supported for interocular adjustment on a bridge b and having graticules 69-70 in the eyepieces. The objective lens 60 and prism 58 are in a box 54 laterally slidable in guides for parallax correction, this movement being effected through a lever system by longitudinal movement of the carriage i by screws 28. A column 75 on the carriage supports the pivot 38 of the bars 80, 81 of a Peaucellier linkage, the arms 82, 83 of which are pivoted at 39 to the shaft 15, and the arms 84, 85 are pivoted at 40 to a lever 43. The lever 43 is fixed to a lever 45 pivoted at 50 and having a movable cursor 47 engaging a lever 46 pivoted at 51 and having a forked end engaging the pin 52 of a sliding bar 53 connected to the box 54. The pantograph carrying a pencil 35, Fig. 4, is pivoted at 33 to a slider 31 movable on a guide 34, Fig. 1, on the carriage i, and is also pivoted to a pin 77 on a slider in a guide 79 which may be set at any angular position on a scale 105 to vary the origin of the plotting radius vector. Lateral movement of the carriage a corresponding to a change in azimuth of the print observed, is transmitted to the pantograph by a pin 14 on the cursor 10, Fig. 4, engaging a lever 17 pivoted to a fixed point 16 and engaging the slider 31 to move the pin 33 as the cursor moves. Operation is as follows : If the photographs were coplanar when taken and the origin of projection is the left-hand objective, the guide 34 is rotated about pin 78 to be parallel to the carriage i and the pin 77 is adjusted to coincide with the axis of the pivot 16, the pins 77 and 38 being connected by a rigid bar. The elevation of the contour to be plotted is set on a scale 25 by adjusting the cursor 22 and the azimuth fixed by cursor 10. By sliding the carriage 30, the parallax between selected points seen in the photograms is corrected by the lever system and the pantograph is automatically adjusted to correspond with the range of the selected points which is plotted on the table 88. The scale of reproduction is varied by movement of the cursor 47 of the lever system. After completing the plot for all azimuths, the elevation is changed and the process repeated. In a modification the column 75 is replaced by a guide supported. on the carriage 26 so as to be movable relative thereto in the direction of the guides 29. The guide supports a pivoted slide having a movable cursor connected by a lever to the arm 17 and by a sliding pin to the slide 76. The pivoted slide is set according to the angle between the photography points when the photographic plates are not co-planar. The Specification contains a mathematical analysis of the operation of the apparatus.