Algorithm based on star map matching for star images registration

Abstract

The camera's motion of detecting and tracking GEOs in spaced-based or ground-based observation platform is very complicated because of the controls of camera's motion for accomplishing the tracking and the motion of platform itself. The controls include: the converts between spontaneous encounter mode and vertical scan mode, detecting and tracking the GEOs with different velocities, etc. The sudden conversion between different modes would make a obvious imaging difference between the two neighbor star-images: stellar shape turn long strip from point, the background's motion is not also uniform linear or constant angular rotation. The imaging difference and irregularity of background's motion enhance the difficulties of star images registration. But the step of registration is necessary in processing of detecting and tracking GEOs based on images sequence. At present almost registration algorithms are designed for some ideal situations or some special conditions needed, thus less of robust to overwhelm the imaging difference and irregularity of background's motion, so most of these are not suitable for automatically detecting and tracking under complicated circumstances in engineering. Another point is that these algorithms are constructed only in image processing level and not consider from astronomy angle. In this paper, an algorithm identifying stars for navigation in astronomy fields is introduced to images registration. For accomplishing to convert camera coordinate to right ascension and declination of sun, there are some parameters should be got in advance, including CCD camera's focal length, field angle and the current camera's axis pointing for building a proper star catalogue. Fortunately to an observation platform, these parameters are known.