Improvements in photogrammetric plotting apparatus of the multiple projector type torender them capable of effecting radial nadir point triangulation

摘要

659,720. Photogrammetry. NISTRI, U. Nov. 8, 1949, No. 28538. Convention date, Feb. 1. [Class 97 (ii)] A support for ganged photograph projectors enabling the rotation of the image projected on a plane 21 around its nadir axis without varying its form is characterized by each projector support being adjustably mounted to render the axis of rotation for orientation vertical. Each projector is attached to a bracket 2 which may be moved by means of micrometer adjusting screws 6, 7, 8, and dovetail slides 3, 4, 5 in the three co-ordinate directions relative to a bar 1 which is common to all the projectors in the gang. By adjusting screws 10 on a support 11, the axis 12 of a stirrup 13 may be rendered vertical, and by means of knob 17 operating a sector 171, the projector 16 may be rotated around the horizontal axis 15 until its optical axis is also vertical as indicated by a level 19 on sector 171 and coincides with the axis 12. The rear nodal point of the lens of projector 16 coincides with the intersection of axes 12, 15. The projector is rotated about its principal axis 20 by means of knob 18, and about axis 15 until the nadir axis, i.e. the line joining the nadir point of the photograph, which has been fixed by any means, with the rear nodal point of the lens, is vertical. The stirrup 13 is then rotated around axis 12 to orientate the image projected on the plane 21. The support bar 1 of the gang of projectors is allowed limited angular movements by means of adjustment screws and also movement in longitudinal and transverse directions in a horizontal plane, by means of screws and return springs.