Research On Acquisition Method Of Two-Dimensional Surface Deformation Field Based On Ascending And Descending Orbits InSAR Data

The increasingly serious global geological disasters have a huge impact on human daily life and social and economic development,most of which are caused by the subsidence and deformation of the earth's surface.Natural disasters such as earthquake deformation,land subsidence,glacier drift and landslides will not only cause surface deformation,but also geological disasters such as excavation of water conservancy projects and exploitation of groundwater.Various types of natural geological disasters have gradually become an important environmental factor affecting the sustainable development of national economy and society.Interferometric synthetic aperture radar(In SAR)measurement technology is a new type of surface deformation monitoring method,which has obvious technical advantages such as all-day,all-weather and wide monitoring range.However,the traditional In SAR technology is limited by the radar imaging geometry.The result of deformation monitoring has the problem of blurred line of sight.This result only represents one-dimensional deformation field in the line of sight direction of the surface radar,and can not fully reflect the actual deformation state of the surface.Since the deformation of the earth's surface can not only occur in a single direction,it is of great practical significance to monitor the two-dimensional deformation field of the earth's surface in both the vertical and horizontal directions.In this dissertation,based on In SAR technology,two-dimensional deformation field acquisition method is studied.Differential In SAR(D-In SAR)and small baseline In SAR(SBAS-In SAR)are used to monitor the large-scale surface deformation in the study area.According to the geometric relationship between the flight direction of the satellite and the ground,combined with the onedimensional deformation field of the ascending and descending orbits,the two-dimensional deformation field of the ground in the vertical and horizontal East-West directions can be obtained,thus solving the problem of blurred line of sight in In SAR technology.The time registration of In SAR observations in the ascending and descending orbits mode is realized by using data interpolation technology,which reduces the influence of time inconsistency between the two on the inversion accuracy of deformation field.The two-dimensional deformation field of the earth's surface can be calculated more accurately by combining the In SAR Data of the lifting orbit after time registration.The specific work content and innovations of this paper are as follows:(1)The development of In SAR technology and its main application in the field of surface deformation monitoring are studied.In this paper,In SAR,D-In SAR,SBAS-In SAR technology and In SAR monitoring of two-dimensional and three-dimensional deformation of the earth's surface are described.The basic principles of In SAR technology are reviewed.On this basis,the technical principles and main processing flow of D-In SAR and SBAS-In SAR are described.The research shows that In SAR technology has great potential in the monitoring of surface deformation.(2)Based on D-In SAR technology and SBAS-In SAR technology,the surface line of sight deformation field is extracted.In this dissertation,two satellite images of sentinel-1A are processed by D-In SAR technology,and the deformation field of Los is obtained.Then,SBAS-In SAR technology is used to process the time series SAR image of 10 satellite sentinel-1A,and the line of sight deformation field is obtained.Finally,the deformation results of descending and ascending orbits are analyzed.(3)A two-dimensional surface deformation monitoring method based on the time registration of descending and ascending orbits observation is proposed.In the process of solving the twodimensional deformation field of the earth's surface by the In SAR observation value of the joint descending and ascending orbits,it is difficult for different satellites to observe the same target synchronously due to the restriction of the satellite orbit parameters,which results in the inconsistency of the observation time of the descending and ascending orbits and reduces the precision of the two-dimensional deformation solution.In this dissertation,the data interpolation technology is used to register the time of In SAR observation value in the descending and ascending orbits.That is to say,taking the acquisition time of SAR time series data in one orbit as a reference,the data interpolation technology is used to interpolate the time cumulative shape variable obtained from the time series data in the other orbit,and the shape variable corresponding to the reference time point is obtained.By comparing the observed value of ascending In SAR before and after time registration with the observed value of descending In SAR,it is found that the observed value of ascending In SAR after time registration is not only the same as the observed value of descending In SAR,but also more close to the monitored value of both.Finally,the two one-dimensional deformation fields in the study area are obtained by solving two one-dimensional deformation variables after time registration.The results show that the proposed method can accurately retrieve the two-dimensional deformation field of the earth's surface.