GB1473017A - Single photo epipolar scan instrument - Google Patents

Abstract

1473017 Photogrammetry BENDIX CORP 24 March 1975 [12 April 1974] 12141/75 Heading H4D In photogrammetric apparatus of the kind wherein the scans of the stereo pair of photographs are along epipolar lines (see Specification 1,363,207), the necessity for scanning the two photographs simultaneously, is obviated by scanning one photograph at a time along predetermined epipolar lines, with the video signal resulting from the first photograph being stored for subsequent correlation comparison with the video signal resulting from the corresponding epipolar scanning of the second photograph. The photograph 64 may be supported on a servo (62, Fig. 1) or hand (60) moved X motion carriage 20 in turn mounted on a servo (42) or hand (40) moved Y motion carriage 16, in turn mounted on a base 14. A light source 202 is fixedly mounted below the photograph with a detector head 204 mounted above and sending the video signals to a memory 70. The servo's are controlled to give the epipolar scanning by a scan control unit 68. To make the required scanning signals less complex, the photograph may be further mounted on a rotatable carriage (78, Fig. 3, not shown) the photograph being thereby rotated such that a single X scan produces the required epipolar scan. A microscope 300 may be incorporated in the base 14 having a viewing axis coincident with that of the light source and detector to initially position the photograph, the light source for the microscope being in the detector head (Fig. 4, not shown). By making the light source case a line image (Fig. 5, not shown) on the photograph along the Y axis and making the detector multielemented, several parallel tracks either side of as well as the epipolar track can be simultaneously scanned. The resultant several video signals being electronically converted to their epipolar equivalents. By making the lens projecting the line image on to the detector or telephoto lens of variable magnification and varying the magnification as the scan proceeds, the several lines can be made convergent or divergent to be all epipolar, no conversion then being needed (Fig. 6, not shown).