Time-frequency Analysis Based PolSAR Image Enhancement And Power Transmission Tower Series Detection

Synthetic Aperture Radar(SAR)imaging is unrestricted by the weather condi-tions,which can make up for the blind spot caused by limits in time and space of optical sensor.Describing the characteristics of the ground target accurately,SAR im-age provides a wealth of information for target detection,which is of great significance for the application of high voltage transmission line network and tower state monitoring.This thesis analyzes the characteristics of Power Transmission Tower in the polarimetric SAR image in detail.According to the analysis conclusion,various information is used in different processing to remove the false alarm targets gradually,integrating with pro-cessing of each level,studying the detection methods of Power Transmission Tower in polarimetric SAR image.The main work and contribution can be organized as follows:Firstly,we briefly introduce the imaging principle of SAR,analysing the noise and distortion of SAR image.Based on the concept of polarization,the scattering characteristics of targets in polarimetric SAR image are discussed.From the point of view of image preprocessing,some common methods of polarimetric SAR image enhancement are studied.Secondly,this thesis explains the basic idea and related principle of time-frequency analysis,and four typical time-frequency analysis methods are introduced.Then,based on the understanding of common polarimetric SAR image enhancement meth-ods,a method of target contrast enhancement in polarimetric SAR image based on time-frequency analysis is proposed according to the scattering characteristics of Power Transmission Tower in polarimetric SAR image.Finally,the characteristics of Power Transmission Tower in polarimetric SAR image are analyzed in detail,according to which a detection scheme is developed.By using the characteristics of bright spot,the initial detection is performed by constant false alarm rate detector.Aiming at a large number of false alarm targets originate from the initial detection,the a-contrario theory is introduced according to the linear arrangement of target group,discussing the a-contrario theory based extraction of Power Transmission Tower series.In summary,many characteristics of Power Transmission Tower in polarimetric SAR image are fully utilized to carry out the Power Transmission Tower detection of polarimetric SAR image,.The experimental results verify the feasibility and effective-ness of the proposed algorithms.