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Information Extraction From SAR And Its Application In Geological Disaster Risk Assessment

Posted on:2013-09-04Degree:MasterType:Thesis
Country:ChinaCandidate:X K LiuFull Text:PDF
GTID:2268330392458377Subject:Geodesy and Survey Engineering
Abstract/Summary:PDF Full Text Request
Three Gorges Reservoir area is located in mountainous areas of central-southChina, with great population density and rivers. It is one of the severest areas ingeological disaster because of its mountainous and complicated geological structure.Traditional geological disaster information is mainly gained in an artificial way. Thedisadvantages of this method are time-consuming, labor-intensive, weak timeliness andlow consistency. Remote Sensing technology has many advantages such as wide rangeobservation, timeliness and high consistency, etc.Geological disasters are often caused by rain and other inclement weather. In suchweather conditions, the optical remote sensing is unsuited. Synthetic aperture radar(SAR) is a kind of imaging radar with an all-day, all-weather, long distances ability,providing high-resolution radar images. Being a new remote sensing technology, SARplays an indispensable role in emergency and prevention of geological disasters.This paper selected Zigui County in Hubei Province as the study area, taking SARremote sensing data as the basic data source. By analysising SAR imagingmechanism and its typical geomatric characteristic, this paper completed SAR imagesimulation and orthorectification. Finally, this paper has given geological disaster riskassessment model for Zigui County. The main works of this paper are as follows:First, by a detailed analysising of geometric characteristics of SAR image, and aindividually judgement of diffenent geometric distortion, the analysis of SAR imagingprinciple and image geometric features is performed, and followed by a comparement ofthe key difference bewteen SAR image and optical image, which provides a theoreticalbasis for the subsequent SAR image orthorectification.Second, this paper gives a detailed derivation of R-D algorithm, and extracts therequired parameters from ENVISAT ASAR matadata of Zigui area. Then, thesimulating method is studied, the corresponding program is developped and thesimulation process is achieved.Third, this paper provides a new method for layover judgmentment. With theorthorectification method based on simulated SAR image, this paper implements theSAR image orthorectification. And an accuracy assessment work of ENVISAT ASAR data in Zigui area shows that the orthorectification method reveals a higher accuracycompared with other common used orthorectification methods..Fourth, based on analysising the correlation between surface roughness andgeological disaster, this paper studies the extraction method of surface roughness fromSAR data. Taking Zigui County as study area, and ASAR and HJ multi-spectral satellitedata as data source, this paper has extracted two kinds of factors, which are oftopography and the environment. Then based on these factors, a risk assessment modelbased on information entropy is used to perform the geological disaster risk assessmentof Zigui County. The ground truth shows that the assessment result is reliable.
Keywords/Search Tags:Remote Sensing, geological disaster risk assessment, synthetic apertureradar, orthorectification
PDF Full Text Request
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