Research On SAR Image Matching Technology Based On Improved ASIFT Algorithm

Along with the development and improvement of synthetic aperture radar(SAR)imaging technology,image matching based on SAR image has been a new hotspot in the field of SAR image processing recently.SAR image matching was the technology of finding some similar measures in two SAR images taken from different periods or different imaging angle or different sensors.How to efficiently extract the stable information in two images and match them with effective methods was the key of the image matching research.As the core technology of SAR image processing,the accuracy and stability of image matching were the cornerstones of all.Therefore,image processing researchers abroad bent themselves to improving the correctness and effectiveness of the image matching.This dissertation mainly focused on the SAR image maching,comprehensively analyzed the applicability of the SIFT algrithm based on SAR image.SAR imaging theory and optimal imaging was described for analysing the radiation and geometric feature differences between the two types of images.The application limitations of the SIFT algorithm in SAR image matching were disscused based on the differences.The simulation experiments proved that the speckle noise in SAR image had the most significant impact on the SIFT algorithm applied in SAR image matching.In consideration of the application limitations of the SIFT algorithm in SAR image matching,this dissertation studied SAR-SIFT algorithm which was put forward by Flora Dellinger and adapted to the SAR image speckle noise,investigated the applicability of SAR-SIFT algorithm to speckle noise in SAR images,meanwhile,improved the SAR-SIFT algorithm to enhance the speed and the stability of the feature points.An improved SAR-SIFT algorithm based on multi extremum suppression and Laplasse transform was proposed in this dissertation.The simulation experiments showed that the improved SAR-SIFT algrithm could be more uniform and stable in feature points which reached an accuracy of subpixel level,and the improved algorithm could be more efficient.The method of matching two SAR images under different view conditons of affine deformation was discussed.An optimal matching technology named Affine-SIFT algorithm with affine invariant including the affine transformation,image perspective sampling,implementation and the effectiveness was studied.A new SAR image matching method conbined the improved SAR-SIFT with ASIFT algorithm was proposed.The final simulation results showed that the new algorithm was much better.