| Based on the background of the "Ten-Five"Technology Project, this thesis introduced some important technology used in the helicopter safely landing system with CCD photometry and in the helicopter optoelectronic guiding equipments. Based on a systemically analysis and study of the accurate orientation technology was brought out, a projection model was proposed to measure the exact position of helicopter. We present two kinds of state estimation methods. One uses four-characters points and estimates the position basing on geometric theory, and the other uses multi-character points and estimates the position basing on matrix theory. In the four characters image process, low-pass filtering and binary image processing was applied. In the multi-character image process, band-pass filtering, segmented image processing, edge detection and linking, corner detection was adopted. This paper proposed a new method in corner detection, which could cut down the time in image processing greatly. An easy and fast method of lens distortion correction by mathematical model of camera on the basis of projective theory is proposed, in which radial distortion center and distortion coefficient were considered. The distortion center was located according to cross ratio invariability, and distortion coefficient was calculated according to a line's central projection is a line. The results show that this method could quickly and conveniently calibrate the camera system with good stability and precision. An experimental system is made to validate the CCD photometry. The system offers the important referenced value to develop the actual helicopter landing system. The system consists of customized software and off-the-shelf hard-ware which performs image processing, segmentation, feature point extraction and motion estimation and allows real-time computation at a frame rate of 5Hz. The experiment results show the distance estimates are accurate to within 1cm in three... |
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