Monitoring And Application Of Regional Landslide Time Series Deformation Based On Optical And SAR Image Offset Tracking

Geological disasters occur frequently in China,especially landslides,which threaten most provinces and cities to varying degrees.Landslides will destroy the surrounding environment,produce huge economic losses,and seriously affect people's lives and property safety.Longterm monitoring of surface deformation in landslide-prone areas can effectively reduce losses,provide important data support for landslide prevention,and have important reference significance for early warning and emergency response of landslide disasters.Compared with traditional landslide monitoring methods,the thesis monitors the deformation based on offset tracking,which can be divided into offset tracking based on optical image and SAR image according to image types.The two technologies can obtain sub-pixel precision ground deformation information by coarse registration and fine registration according to their respective image characteristics,which has the ability of deformation monitoring in a large gradient,non-volatile correlation,fast and high precision,and provides a new monitoring method for long time series and large scale landslide monitoring.The research status,algorithm,data processing process and precision image factors of offset tracking based on optical and SAR images are analyzed respectively,and the offset tracking error and time series offset tracking method are discussed.The time series deformation information before Baige landslide is obtained based on offset tracking.The research results are as follows:1.An adaptive equal mean subtraction method is proposed.In view of the non-uniform distribution of attitude angle error of Sentinel-2 satellite and its easy fluctuation with the topography,this paper adaptively simulates and removes attitude angle error of satellite based on the threshold of deformation difference between adjacent pixels and the threshold of pixel number.Compared with the existing methods,the proposed method improves the accuracy of offset tracking of Sentinel-2 single image pair and the results of long-term landslide deformation monitoring.2.A joint solution method of dual-platform time series deformation based on Sentinel-2and Landsat8 is proposed.In view of the low time resolution of time series deformation of single platform,this paper firstly estimates the time series deformation of two platforms separately,then estimates the time series deformation of two platforms jointly,and finally evaluates the accuracy of the time series deformation results of two platforms,delineates the landslide stage and analyzes the correlation of rainfall.The results show that:(1)The accuracy of dual-platform timing offset is better than that of single-platform time series deformation;Under similar observation conditions,Sentinel-2 has better monitoring accuracy than Landsat8.(2)From November 2014 to September 2018,Baige landslide can be divided into the initial stage,the uniform stage,the initial acceleration and the medium-term acceleration.(3)Time series deformation is highly correlated with rainfall.3.Using ALOS/PALSAR data to analyze the surface deformation information of Baige landslide,the process of estimating the time series deformation of SAR image baseline set is expounded in detail.Based on the above analysis,this paper obtained the deformation information of Baige landslide from January 2007 to February 2009,evaluated the accuracy of the deformation results,supplemented the time-series offset estimation results of optical images,and obtained the deformation information of Baige landslide in a longer time series.