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针对已有的围填海图斑提取方法精度不高、普适性不强、自动提取结果不理想等问题,该文提出了通过构建归一化差异水体指数(NDWI)进行围填海变化图斑自动提取的方法。以高分辨率QuickBird影像和HJ-1卫星影像为数据源,首先,根据研究区的用海类型进行5种易混淆地物的波谱特征分析;然后,根据水体与非水体的光谱特征差异,构建2009、2011年两个时相的NDWI指数;最后,将两时相NDWI指数影像进行空间相减,设置判断阈值,识别围填海变化图斑,并以目视提取结果作为依据验证其自动提取效果。对比分析结果表明:利用该文构建的两期NDWI指数可以将大部分围填海区域准确、自动地探测出来,可以将该方法纳入到沿海地区围填海变化监测的业务中。
In view of the problems such as low accuracy, poor universality and unsatisfactory automatic extraction results of existing reclamation seafloor spot extraction methods, this paper proposes a recalculation chart of reclamation by constructing normalized difference water body index (NDWI) Spot automatic extraction method. Based on the high-resolution QuickBird images and HJ-1 satellite images, the spectral characteristics of five kinds of obscure objects were analyzed based on the sea types in the study area. Then, based on the spectral features of water bodies and non-water bodies, 2009 and 2011 respectively. Finally, the NDWI index of the two temporal NDWI images is spatially subtracted, and the thresholds are set to identify the changes of the reclamation seafloor. The visual extraction results are used to verify the NDWI index effect. The results of comparative analysis show that most of the reclamation areas can be accurately and automatically detected by using the two NDWI indices constructed in this paper, which can be incorporated into the business of coastal reclamation monitoring in coastal areas.