Analysis Of Scattering Characteristics Of Objects And Tidal Channel Information Extraction Of Jiuduan Shoal In The Yangtze River Estuary Using Remote Sensing Data

Tidal channel is an important part of the tidal flat sedimentary landform unit.The mass transfer and energy exchange of tidal flat and offshore through the tidal channel,tidal channel has an important influence on the evolution of tidal flat and the vegetation community development.At the same time,it has certain regulation for the organic matter,sediment and nutrient in the water.Remote sensing technology has a greater advantage than conventional monitoring methods and has the characteristics of large area and real-time monitoring.Carrying out the remote sensing research of tidal channels information,can provide scientific basis for the development and protection of tidal flat resources.In the dissertation,analyzed the scattering characteristics of objects and extracted tidal channel information of the Jiuduan Shoal in Yangtze River Estuary based on Radarsat-2 microwave and Landsat 8 optical remote sensing data.In the course of study,the research results are as follows :(1)Radarsat-2 full polarization data was selected on April 5,2015.Firstly the multi-look processing and Lee refined polarized filter to the image to eliminate the speckle noise caused by the radar system,then Pauli decomposition for the target was performed to obtain singular scattering coefficient ? dihedral angle scattering coefficient and45°dihedral angle scattering coefficient.After that the statistical analysis of the scattering intensity of the Jiuduan Shoal sand was carried out.Finally,according to the statistical results,the dihedral angle scattering coefficient was selected as the criterion for the information extraction of tidal channel,and the information of tidal channel in the Jiuduan Shoal was extracted with the method of regional growth and mathematical morphology.(2)Three different types of tidal channels in panchromatic band remote sensing data received from Landsat-8 satellite on February 15,2015 were selected.Firstly,the top-hat transformation was to eliminate the problem of the backgrounds of uneven brightnessaccurately,if the method of maximum between-class variance(Otsu)was used directly;Then,Otsu was used to find an optimal threshold to make the maximum variance between tidal channel and background,obtaining a binary image;Thirdly,the complete information of tidal channel was gained by mathematical morphology.Using visual analysis and quantitative analysis to evaluate the accuracy of the information of tidal channel.The result shows that the method combing Otsu with mathematical morphology can be used to extract tidal channel information efficiently.