A good similarity measure is the key to robust template matching. In this paper, we present a Similarity-Transform invariant Best-Buddies Similarity (SiTi-BBS) to deal with the template matching with obvious geometric distortion. Similar to the BBP, SiTi-BBS still adopts Best-Buddies Pair (BBP) to vote. However, differing from the classic BBS acquiring the point pair via bidirectional matching in xyRGB space, SiTi-BBS takes only the color information (RGB components) to acquire BBPs, while the position information (xy components) of each BBP is employed to calculate the geometric distortion between the template and matching window. To further improve the robustness of template matching, we novelly take advantage of the interval voting to accommodate the case where the two images do not strictly satisfy the similarity transformation. Therefore, SiTi-BBS, to a certain extent, can be applied to the affine and perspective transformation. In this way, the highest number of votes is taken as the similarity measure between the two images. Mathematical analysis indicates that the proposed method is capable of dealing with the case of obvious geometric distortion between images. Furthermore, the test results of simulated and real challenging images show the outstanding performance of the proposed similarity measure for template matching.
The technique of the star image simulation is widely used to test star identification algorithms and the performance of
star sensor on the ground. A novel INS data based approach to ship-borne star map simulation is put forward in this
paper. The simulation procedure consists of three steps: Firstly, the exact speed and position of the ship in the
Conventional Inertial System(CIS) are calculated via the INS data; and then the ship attitude matrix is obtained.
Secondly, considering the azimuth angle and elevation angle of the star sensor, the accurate positions of the selected
guide stars on the image plane of the star sensor are derived by constructing a pinhole model. At the third, the gray
values of simulating star image pixels are evaluated according to the 2D Gaussian distribution law. In order to simulate
the star image precisely and actually, the image smear has been considered. Based on the proposed star image simulation
approach, the effects of image smear on star sensor recognition capability have been analyzed in different exposure time.