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US 2015/0085147 A1Published application
Stabilization of a line of sight of an on-board satellite imaging system
AssigneeAirbus Defence and Space GmbH
InventorPierre-Luc Georgy
Life of this patent
Estimating the term…
Abstract
A method for stabilizing a line of sight of an imaging system on board a satellite uses windows selected within an image sensor. Variations of the line of sight can be characterized at a frequency that is greater than that of a sequential mode of image acquisition by the sensor. The stabilization method can be implemented at the same time as the full-frame acquisition of images by means of the imaging system.
Claims22
Method for stabilizing a line of sight of an imaging system on-board a satellite, said imaging system comprising:
- a telescope arranged to form an image of a scene in a focal plane, according to the line of sight of the imaging system;
- and
- at least one matrix image sensor arranged in the focal plane and suitable for capturing successive images in a sequential mode, in which photodetectors of the sensor are successively and individually controlled during an accumulation phase of a detection signal for received radiation, followed by a read phase of an accumulated signal, based on an order for scanning the photodetectors that is repeated in a continuous loop, each repetition of scan of the photodetectors corresponding to a newly captured image, and the read phase for any of the photodetectors being carried out at the same time as the accumulation phase for other ones of the photodetectors;
- wherein, for several windows, each of which consists of a different subset of adjacent photodetectors within the sensor, each window being smaller than a total use surface of the sensor, an image portion captured in one of the windows during one of the repetitions of the scan of the photodetectors is compared with a reference image content for the same window, so as to characterize a variation of the line of sight between said repetition of the scan of photodetectors and a reference scan, and a new characterization of the variation of the line of sight being obtained separately for each window at each repetition of the scan of the photodetectors;
- and wherein an orientation of at least part of the imaging system is changed so as to modify the line of sight to compensate, at least partially, for the variation of said line of sight.
2 more elements
An imaging system intended to be placed on board a satellite and suitable for stabilizing a line of sight of said imaging system, comprising:
- a telescope arranged to form an image of a scene in a focal plane, according to the line of sight of the imaging system;
- at least one matrix image sensor arranged in the focal plane and suitable for capturing successive images in a sequential mode, in which photodetectors of the sensor are successively and individually controlled during an accumulation phase of a detection signal for received radiation, followed by a read phase of an accumulated signal, based on an order for scanning the photodetectors that is repeated continuously in a loop, each repetition of scan of the photodetectors corresponding to a newly captured image, and the read phase for any of the photodetectors being carried out at the same time as the accumulation phase for other ones of the photodetectors;
- and
- an image comparison unit, which is suitable for selecting several windows each of which consists of a different subset of adjacent photodetectors within the sensor, each window being smaller than a total use surface of the sensor, and suitable for comparing a portion of the image captured in one of the windows during one of the repetitions of the scan of the photodetectors with a reference image (Ra-Rd) content for the same window, so as to characterize a variation of the line of sight between said repetition of the scan of the photodetectors and a reference scan, and suitable for obtaining a new characterization of the variation of the line of sight separately for each window at each repetition of the scan of the photodetectors;
- and
- a control unit suitable for controlling a change in an orientation of at least part of the imaging system so as to modify the line of sight to compensate, at least partially, for the variation of said line of sight.
3 more elements
Dependencies are inferred from the claim text.