Water Body Automatic Extraction From Landsat Image In Poyang Lake

In recent years, the global water environment was going worse. How to use remote sensing technology in real-time, accurate and efficient to extract water body information has become a key issue in many field. The automated processing of remote sensing data into information technology or knowledge needs urgent decisions. Remote Sensing for its strong macro, high spatial and temporal resolution, fast real-time response and low cost, these characteristics increase environmental remote sensing technology used in all types of worker environment (such as soil environment, vegetation and water environment, etc.). The Landsat TM / ETM+ images with its high spatial and temporal resolution (16d,30m), and its information-rich body of water, so as to it is widely used in water extraction.In this paper, in the base of a variety of water extraction index, building a new water extraction index--Comprehensive Weight Water extraction Index, to extract water body in Poyang Lake, the main research results are as follows:(1) By using several water index and color transform method to extract Poyang Lake’s water body. And by comparing the results to find an available and appropriate index to exactly extract the Poyang Lake’s water body(2) Build comprehensive weight water extraction index. Based on the spectral relationship water extraction model and AWEI water index model, using the ratio of each band average gray value as the band’coefficient in new water index model. In this model the information of non-water was suppressed, and the information of water was enhance, so as to improve the accuracy of water body extraction in Poyang Lake.(3) Segmentation gray image which was processed by water body extract index with the threshold. In this paper, three kinds of threshold segmentation method had been used to get the best threshold, there are adaptive iterative method, OSTU and two-dimensional entropy method. In order to select the best segmentation method, the precision and time consuming were compared with the extraction result in Poyang Lake.