10 December 2014 An automatic method of monitoring water bodies based on GF-1 data
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As the reflectivity is very low in near-infrared spectral band for water, it is easy to extract water bodies in remote sensing images with the use of NDVI (Normalized Difference Vegetation Index).The problem is that we always have to try several times to find the appropriate threshold to separate water bodies from land. In this paper, a particular method was developed to solve this problem by automatically determining the threshold that was used to extract the specific water body. We select both Chaohu Lake and Taihu Lake as the study regions. First, we generate NDVI image of the study region from GF-1 data after several pre-processing procedures. Then we resize the NDVI image to make it contain approximately the same number of water and land pixels. Because the NDVI value is lower for water than that for land, there will appear two peaks in the histogram which we derived from the resized NDVI image. The threshold locates at the lowest place between the two peaks can be chosen as the proper threshold used for land/water delineation. With the use of a reasonable threshold range we can finally get the threshold by calculating the minimum value in it, and extract the water body successfully.
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HaoBin Zhang, HaoBin Zhang, JunSheng Li, JunSheng Li, Nanping Xiang, Nanping Xiang, Qian Shen, Qian Shen, FangFang Zhang, FangFang Zhang, Wenxiu Liang, Wenxiu Liang, "An automatic method of monitoring water bodies based on GF-1 data", Proc. SPIE 9261, Ocean Remote Sensing and Monitoring from Space, 926103 (10 December 2014); doi: 10.1117/12.2068815; https://doi.org/10.1117/12.2068815

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