Waterline Extraction Of Muddy Tidal Flats Based On Wavelet Methods

The Coastal Zone is the highly dynamic zone where the Ocean and the Land interact, and it's the key area where the near shore environment monitoring pays a large attention to. Since the application of remote sensing in the coastal research, the shoreline feature extracted from remote sensing images has become a fundamental work. Due to the special substance composition and flat landform in the muddy tidal flats, especially the suspended-sediments in the estuarine water, it is a difficulty job to extract waterline from coastal remote sensing imagery precisely.The waterline technique is an available method which uses remote sensing to inverse the tidal topography and to quantitatively calculate erosion and siltation in the tidal flats. In order to get a good result, a high precision method to extract the waterlines from the remote sensing images is needed. On an account of the artificial digital time-consuming, this paper uses the wavelet method to extract the waterline. The most work as follows:The first chapter is a review, focuses on the present research progress about the shoreline features extraction from the remote sensing images, and makes a detail analysis on the progress of the shoreline extraction.The second chapter outlines the general features of the muddy tidal flat. And according to the concrete condition of Chongming island flats, the classic spectrum of different muddy flats objects are analyzed. Furthermore, after a detail analysis of the spectrum character, a principle about spectral band selection to extract the shoreline is proposed.The third chapter concerns the wavelet method of the waterline extraction. According to the characteristics of Landsat TM images, the first step to process the images is based on gray morphology theory, and then acquires the waterline of tidal flats at different scales by means of wavelet transform modulus maxima. With two images with different tidal condition, the results show methods effectively solves the problem that the detected waterline edges are not continuous and many loose edge points exist in high detail areas.Vector data is needed to update geospatial database. Considering the difficulty of data conversion among different system platforms, a new method is developed, which integrates the MatLab function to ArcGIS software based on component technology. First, the MatLab codes are packaged in the form of NET DLL component by Net Builder tool. Then this component is introduced to VB.NET 2005. Finally the VB2005 code is also compiled to COM component and can be executed in ArcGIS software. At last, the integration method leads to extract the waterline feature automatically.