Method and means for compensating for image motion in an aerial camera
First Claim
1. A method of compensating for image motion in an aerial camera in which a slotted shutter (11) moves transverse to the direction of film (6) transport and in which film transport is parallel to the direction of flight, and further in which film-transport speed VT in the image plane is controlled as a function of the ratio of the speed of flight VF to the altitude h, the focal length f of the camera lens, and the inclination β
- '"'"' of the camera, characterized by the fact that the position (x) of the shutter slot (S) is continuously measured in the course of making an exposure, and the drive motor (8) for film transport (7) is governed by a control signal derived from the measured position (x) of the slot (S).
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Accused Products
Abstract
The invention contemplates image-motion compensation in an aerial camera in which the slot of a focal-plane shutter (11) moves in a direction transverse to the direction of film (6) transport, and in which film transport is parallel to the direction of flight. In order to compensate for the component of image-motion which is dependent on the field angle and which occurs with laterally inclined displacements of the camera, the slotted shutter (11) is coupled with an encoder (17) which in the course of making the exposure reports to a computer (12) the instantaneous field position (x) of the shutter slot. This computer (12) also determines a speed profile (A, B) in the interval between successive exposures the speed profile being derived from ground-clearance altitude h, flight velocity VF, focal length f, angle of swing β'"'"', and a basic function which is dependent on the type of lens. The computer interprets the feed back signal from the encoder (17) against the speed profile to determine a control signal to regulate the film drive (7, 8).
The single lens (5) of the camera can be replaced by a multiple-lens configuration (35), with the fields of the individual lenses in lateral overlap or adjacency to produce wide-angle coverage, in which case the single slot of a single focal-plane shutter may scan all the fields of the individual lenses in a single exposure sweep.
For the situation in which a lens or lenses must be changed for adaptation to particular requirements, the lens mounts are coded with lens data, and a code reader (41) coupled to the lens mount provides input data to the computer for selection of the corresponding basic function stored in the computer for the calculation of the speed profile (A, B).
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Citations
11 Claims
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1. A method of compensating for image motion in an aerial camera in which a slotted shutter (11) moves transverse to the direction of film (6) transport and in which film transport is parallel to the direction of flight, and further in which film-transport speed VT in the image plane is controlled as a function of the ratio of the speed of flight VF to the altitude h, the focal length f of the camera lens, and the inclination β
- '"'"' of the camera, characterized by the fact that the position (x) of the shutter slot (S) is continuously measured in the course of making an exposure, and the drive motor (8) for film transport (7) is governed by a control signal derived from the measured position (x) of the slot (S).
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
- 9. In an aerial camera system having a lens establishing a terrain image in a focal plane of film support, film-transport means for advancing film in said plane in a direction parallel to the direction of flight, and a focal-plane shutter including drive means for effecting successive film exposures through shutter-slot motion transverse to the flight direction, the improvement in which transducer means is provided to track shutter-slot motion and to deliver an output-signal indicative of instantaneous position of the shutter slot in its shutter-exposure cycle, and in which said film-transport means includes control means connected for response to said output signal.
Specification