In the context of applications of spatial large aperture tracking cameras
calibration errors of the principal point and distance and associated distortions are considered to be important issues in the problem of on-obit geometric positioning. To meet the high-precision calibration demands on spatial large-aperture tracking cameras
factors of the distortion types
calibration errors of the principal point and distance
as well as rotation and inclination of the detector array
must all be addressed. To solve these problems
this paper analyzes distortion characteristics of systems of this type and proposes an improved distortion correction method for large aperture tracking cameras. First
the optical principal point and distance are ascertained using 13 points on the small central area of the focal plane via the least square method. Following that
the theoretical coordinates of the 25 test points distributed uniformly on the focal plane are calculated with the help of the recently acquired principal point and distance. Finally
the parameters of the distortion model are estimated using the theoretical coordinates and the measured coordinates of the test points
and the distortions of the camera are corrected. Experimental results showed that even distortion errors of less than 0.32 pixels and 0.28 pixels were corrected by the proposed method in a near-infrared image and a short-wavelength infrared image
respectively. Thus
the distortion correction is 44.6% and 50.9% better than that of conventional distortion models. Thus
the proposed method provides a beneficial reference in the research concerning the obliquity of the focal plane of large aperture tracking cameras.
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references
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