| As a country with frequent geological disasters,geological disasters occur in a wide range of areas,with a high frequency,many types and large losses.In the decision on strengthening the prevention and control of geological disasters,the state council put forward the goal of geological disaster prevention and control that "by2020,the geological disaster investigation and evaluation system,the monitoring and early warning system,the prevention and control system and the emergency system should be built in an all-round way".In order to achieve this goal,the disaster risk can be effectively reduced through efficient monitoring means and the establishment of early warning system.The detailed information of geological disasters can be accurately obtained by using remote sensing technology in large-scale spatial angle,so as to achieve the purpose of comprehensive monitoring of geological disasters.Based on Sentinel-1A ascending and descending orbit data of Maoxian and its adjacent areas in Sichuan Province,the surface deformation data of Maoxian in 2017 were obtained based on SBAS-InSAR technology,and the surface deformation characteristics analysis and potential landslide identification were carried out.On the basis of obtaining the deformation characteristics of the experimental area and identifying the potential disaster points,the virtual simulation environment was built by using Unity 3D software platform.Combined with augmented reality technology,a real-time three-dimensional display system for the monitoring area on PC and mobile terminals has been developed.Specific achievements include:(1)Based on the subsidence data extracted by D-InSAR technology,the subsidence monitoring results of Maoxian county are analyzed quantitatively,and the land surface subsidence in the study area from early March 2017 to the end of December 2017 was obtained.By extracting the surface subsidence value and combining with geographical coordinates,the spatiotemporal evolution law of land subsidence is obtained,and established the time series three-dimensional subsidence model.(2)Based on the Sentinel-1A ascending and descending orbit data of Maoxian and its adjacent areas in 2017,the regional surface deformation data are obtained by using SBAS-InSAR technology,and the spatial vertical deformation characteristics are analyzed.The research results shows that the accumulated deformation of the area in 2017 is dominated by settlement.The areas with serious subsidence mainly occurred in Taiping Township and Qingpian Qiang Autonomous Township in the northeast,followed by the south,and relatively slightly uplifted in the northwest.With the development of regional large-scale settlement,the state of concentrated regional settlement has been formed.(3)This paper presentd a data processing method of using wavelet analysis to filter and differential process DEM of different periods obtained by SAR technology,so as to obtain the actual settlement range of large-scale area.The realization methods are as follows: eight SAR data of the experimental area at the beginning and the end of 2017 are selected,and four DEM data sources are formed after preprocessing.Then,the wavelet analysis technology was used to calculate the mean value of the low-frequency part of the early stage and the final stage of the orbit lifting data,and the high-frequency coefficient is used as the target wavelet coefficient to generate the two scenes fusion DEM.Finally,the data after fusion and before fusion are processed to get the settlement deformation area in a large scale.By randomly selecting sample points to verify,it showed that the method can extract the deformation range consistent with the actual in the decoherence region.(4)After using the above(1)?(3)techniques and methods to complete the identification of landslide and disaster hidden danger points in the experimental area,combined with geographical location information and high spatial resolution remote sensing images,the real distribution location of hidden danger points is determined.Based on Unity 3D,combined with VR and AR technology,the 3D modeling and virtual simulation environment of geological hazard hidden points are built,and finally the user-side real-time 3D virtual visualization system of disaster area has been developed.(5)This paper analyzed and studied the causes of geological disasters in Maoxian county and its adjacent areas.The results shows that: the main factors of landslide formation are related to many factors,such as stratum landform,altitude,aspect,historical earthquake and abundant water.Although rainfall has a short lag type with landslide deformation,it has a positive correlation. |
PDF Full Text Request