Research On Key Technologies Of Dual Airborne SAR Stereo Positioning

In order to further realize the acquisition of the target located in the region where it is difficult to establish ground control points such as desert,sea surface or abroad territory using airborne SAR(Synthetic Aperture Radar)images,the airborne SAR image localization system should have the ability to accurately locate the target without control points.In this paper,the research on the stereo positioning method of dual airborne SAR based on Range-Doppler model is carried out.The main work contents are as follows:(1)The methods of positioning with stereo SAR images with control points and no control points are introduced respectively,and the application range and difficulty of implementation of them are analyzed.In order to accurately locate the target without the ground control points or other models,the scheme of dual airborne SAR stereo positioning based on the RangeDoppler algorithm is designed.(2)The problems such as low matching accuracy and poor real-time performance between the two SAR images are solved from the two aspects of image preprocessing and detection matching.The wavelet transform filtering method with better edge information retention is used to reduce the interference of speckle noise on the target.The Otsu segmentation algorithm is used to enhance the contrast between the target and the background.To improve the speed and accuracy of feature points matching,the Harris scale invariant detector is introduced in the SIFT detection matching algorithm.(3)The stereo positioning model of dual airborne SAR based on Range-Doppler model is established,and the corresponding positioning error model is derived.The simulated SAR image is used to verify the stereo positioning algorithm of dual airborne SAR.The result shows,the algorithm studied has a positioning error of 14 m when the target distance detector is 8.078 km away,which is better than the single SAR image positioning technology under the same condition.The error is simulated by the positioning error model for the main factors such as the position and speed of the carrier.Simulation results show that when the position error of the carrier is 10.4m,the target positioning error is at least 20 m and when the carrier speed error is 0.7m/s,the target positioning error is at least 67 m.(4)The software of dual airborne SAR stereo positioning system based on Harris-SIFT image matching is designed with the platform of MATLAB,and it is used to simulate locating process of the target on the sea surface under given input conditions.