Research On Automatic Method Of SBAS-InSAR Data Processing

Land subsidence disaster threatens national economic security directly.There are some traditional land subsidence monitoring methods such as common leveling measurement,high precision of GPS and so on,but these methods need to set point at the scene,it’s not only costly,long cycle of measurement,but also low monitoring frequency,sparse measurement points.In order to overcome these defects,scholars have put forward the short baseline differential interference measurement(SBAS-InSAR)method,which uses the time series of homologous synthetic aperture radar data;process these data by sequential interference for surface subsidence monitoring,in recent years.The method can monitor long-time and slow land subsidence effectively;however the current SBAS-InSAR method has a lot of manual interaction and depends on the operator’s experience.In order to reduce human interaction and improve automation,this paper put forward the automated GCP selection method based on interferometric phase and coherent coefficient,the automated method of building effective interferometry-pairs and the filtering of surface deformation monitoring results,then based on these methods to improve SARScape,the SAR interferometry software.The main research contents and results of this paper include:(1)By analyzing the current automated GCP selection methods of visible spectral remote sensing and SAR image,and the refinement GCP selection rules of SBAS-InSAR,then according to the characteristics of interferometric phase and coherent coefficient,the paper put forward the automated GCP selection method combined with on the interferometric phase and coherent coefficient.This method can not only improve the efficiency and precision of GCP selected,but also enhance the automation of SBAS-InSAR.(2)According to the principle of SBAS-InSAR,we can know that the quality of interferometry-pairs,phase unwrapping has a great influence on the accuracy of deformation monitoring results.Therefore,in order to reduce errors,it is necessary to evaluate the quality of phase unwrapping,remove the interferometry-pairs of low quality and build a reasonable interferometry-pairs’network.Hence,the paper put forward a quality evaluation method of interferometry pair’s phase unwrapping based on weighted sum of phase difference,and then on the basis of this put forward an automated algorithm of building effective interferometry-pairs’ network,considering connectedness of interferometry-pairs’ network.(3)Due to the result of surface deformation monitoring contains pulse noise(spike noise),the whole features expression of the regional deformation monitoring results will be influenced.In order to not only don’t affect the precision of deformation monitoring results,but also can show characters of the whole regional deformation,in this paper,comparing analysis of different filter’s effect,with this prerequisite the paper used median filtering to process the result of the deformation monitoring,and achieved good effect.(4)Through in-depth analysis of SARScape’s each module,combining with the improvement of the above three aspects,the paper designs and develops the land subsidence radar interferometry operational system.