The Research On Optimization Technology Of Stars Control Points In Geometric Correction Of Space-Based Optical Image

At present,the world's major military powers are committed to the construction of strategic early warning system and space-based early warning system is an important part of the strategic early warning system.The geometric correction technique of the space-based optical image is the basic step of the space-based early warning system.The accuracy of the image correction directly affects the effect of subsequent geometric positioning,target detection and target tracking.The selection of control points is a key step in geometric correction of remote sensing image.The focus of this paper is that how to use control points to make more accurate corrections to space-based optical images.In the field of geometric correction of remote sensing images,most of the application scenarios use ground control points for geometric correction.Ground control points are sometimes affected by changes in light,seasonal changes,cloud cover and other factors that lead to it can not be observed.Considering the position and radiation stability of the star in space,this paper uses the stars as the control points to carry on the geometric correction of the space-based optical image.The optimization technology of SCPs refers to the number of stars in the case of sufficient control points to filter the process.Not only requires the selection of the control point to extract a higher precision,but also to ensure uniform distribution of control points.The purpose of the control point is to improve the accuracy and accuracy of the geometric correction,so we can use the accuracy of geometric correction to evaluate the preferred results.In this paper,the optimization techniques of SCPs in geometric correction of space-based optical images are studied deeply,and some research results are obtained.(1)The basic methods and principles of image geometric correction are introduced.These theories have geometric correction principle,space-based sensor imaging model,satellite basic coordinate system definition and the transformation between the coordinate system,the main factors affecting the accuracy of geometric correction and so on.(2)Aiming at the situation that the number of visible stars in the field of view is small,the optimization technology of star control points based on cross validation is studied.Firstly,the observing ability of satellites under high orbit is analyzed,and the experimental results show that the visible star points can meet the basic requirements of geometric correction.Then,the influence of the number of star control points and the spatial distribution on the precision of geometric correction is analyzed,and the intention of the selection of control points is obtained.Finally,the optimization algorithm of star control points based on cross validation principle is discussed,and the optimal flow of star control points is clarified,and the simulation experiments are carried out.The experimental results show that the algorithm has better performance in improving the accuracy of geometric correction.(3)Aiming at the situation that the number of visible stars in the field of view is large,the optimization technique of star control points based on random sampling consistency algorithm is studied.Firstly,the principle of RANSAC is discussed,and the experiment of fitting straight line model and ellipse model based on RANSAC algorithm is implemented.Then,the time complexity of contrasting CV algorithm and RANSAC algorithm is analyzed.Finally,on the basis of fully studying the principle of RANSAC algorithm,the concrete implementation process of RANSAC algorithm in star control point optimization technology is given.