遥感图像非监督分类分析江宁县江滩钉螺孳生地植被特征  

Application of satellite image for surveillance of vegetation landscapes of Oncomelenia-snail habitats in marshland using unsupervised classification

作　　者：张治英[1] 徐德忠[1] 孙志东[1] 张波[1] 周晓农[2] 周云[3] 龚自力 刘士军 

机构地区：[1]第四军医大学预防医学系流行病学教研室,西安710032 [2]中国疾病预防控制中心寄生虫病预防控制所 [3]江苏省江宁县血吸虫病防治站 [4]南京军区卫生防疫队

出　　处：《中华流行病学杂志》2003年第4期261-264,共4页Chinese Journal of Epidemiology

基　　金：全军"十五"指令性课题资助项目( 0 1L0 78)

摘　　要：目的　从遥感图像中提取江宁县江滩钉螺孳生地的植被特征。方法　在ERDASIMAGINE 8.5软件支持下 ,根据LANDSAT7ETM图像中各波段的光谱特征 ,选择对植被敏感的 2、3、4波段的伪彩色复合图像ETM2 34进行非监督分类 ,并通过计算分离率 (TD值 )对分类效果进行评价 ;同时将分类结果图与江宁县江滩钉螺孳生地矢量图重叠 ,提取江宁县江滩钉螺孳生地的植被特征 ,并分析钉螺在各植被中的分布。结果　通过对ETM2 34进行非监督分类 ,可将江宁县江滩地表特征分为包括水、沙滩、裸露地表等非植被区域在内的 1 0种地表类型 ;对分类分离率评价显示 ,虽然总体分离率较好 (TD =1 860 ) ,但存在类间的混杂错分。为了进一步提高分类效率 ,以植被指数为参考滤掉ETM2 34图像中无植被的像素然后再进行分类 ,消除了非相邻类间的混杂错分。提取江宁县江滩钉螺孳生地植被类型发现 ,钉螺孳生地的植被主要为非监督分类的第 3(C3)、5(C5)、6(C6)三类 ,且钉螺密度以C3<C5<C6 ,实地考察显示该三类分别为植被稀疏的滩面、杂草丛及芦苇滩。结论通过对遥感图像适当分析能将江滩钉螺孳生地的植被种类有效地鉴别出来 ,有利于对钉螺孳生地的监测 。Objective To explore the vegetation landscapes in marshland snail habitats using satellite image. Methods The false color composition image from band 2, 3 and 4 of LANDSAT ETM+ images was classified in the ERDAS IMAGINE 8.5 to analyze the vegetation types in the marshland of Jiangning county, using the unsupervised classification. The efficiency of classification was evaluated by the transformed divergence. The overlaid layers of the classified vegetation image and the vector layer of snail habitats distribution were used to analyze the relationship between the snail distribution and the landscape types. Results The land cover of marshland in LANDSAT ETM234 image in Jiangning county could be classified into 10 types, including water, bare soil, sandy and other landscapes while the transformed divergence analysis showed that there were misclassified pixes between some types especially for the non continuous types. The study indicated that through adding the NDVI image in the process of classification efficiency of classification and eliminate misclassification in the non continuous type could be improved. Analysis on the overlaid layer of the vector of snail distribution and the classified image proved that the vegetation covers in marshland snail habitats in Jiangning mainly belonged to type 3, 5 and 6, that responded to the beach with sparse vegetation,exuberant weed and bulrush respectively. The density of snails in the bulrush was higher than that in other 2 landscapes. Conclusion The vegetation type in the marshland snail habitats could be distinguished from the satellite image, which was helpful for the surveillance of snail habitat in marshland and for the prevention of schistosomiasis.

关 键 词：血吸虫病 遥感 钉螺 非监督分类 

分 类 号：R181.3[医药卫生—流行病学]