Research On The L~1 Norm Phase Unwrapping Considering Terrain Factors

Synthetic Aperture Radar Interferometry(In SAR)technology plays an irreplaceable role in surface deformation,ocean mapping,land survey,environmental monitoring,disaster analysis,glacier research,national defense construction and so on.This paper expounds that the vigorous development of SAR technology is of great significance to China's surveying and mapping industry.The development status and existing problems of In SAR technology at home and abroad are discussed.Select the difficult part of In SAR technology to tackle.This paper introduces the geometric principle of SAR interferometry,understands the essence of SAR image data,and helps to understand the data form throughout the whole In SAR Data processing process.Through formula deduction,the error source and error model in the process of In SAR DEM inversion are analyzed.Based on the in-depth understanding of the In SAR data processing process,this paper studies the key technologies of the processing steps,and makes some technical improvements in the filtering and phase unwrapping of interferogram.The main research results are as follows:(1)Two kinds of interferogram filtering algorithms are analyzed theoretically.The advantages and limitations of spatial domain filtering and frequency domain filtering are discussed.In view of the important influence of interferogram filtering steps on the subsequent phase unwrapping work,and considering the performance requirements of terrain change on unwrapping algorithm,a local frequency estimation filtering method based on amended matrix pencil model is demonstrated.The performance of the filtering algorithm is verified by multiple groups of experiments on simulated data and real data..(2)Various classical phase unwrapping algorithms are derived by formula calculation,and the essence of phase unwrapping algorithm is understood,and their application scope and limitations are understood.Based on the in-depth study of popular network flow phase unwrapping algorithm,the traditional L1 norm phase unwrapping algorithm is improved on the basis of considering different terrain.The amended matrix pencil model is combined with L1 norm phase unwrapping algorithm to limit the transmission of phase unwrapping error to a certain extent.At the same time,the terrain slope calculation is introduced into In SAR Data processing flow,It improves the accuracy and efficiency of the traditional L1 norm phase unwrapping algorithm.The accuracy,reliability and efficiency of the proposed unwrapping algorithm are verified by experiments on simulated data and real data.(3)An easy to understand data processing software for In SAR is developed.The software is developed based on MATLAB(r2020b),which integrates the basic function modules of interferometric SAR data processing,including interferogram phase filtering,phase unwrapping,phase height conversion,geocoding and DEM production.The purpose of this paper is to verify the practicability of the proposed filtering and unwrapping algorithm.