以位于水蚀风蚀复合区的陕西省横山县为例,通过分析土地覆被类型在TM影像上的光谱特征,选择不同的特征参数,逐层提取有关信息:首先用TM5/Tm^3提取水体,然后用NDVI分离植被和非植被;在非植被区,用NDBI和NDVI相结合提取城镇用地,再用TM5将沙地和荒草地分离;在植被区,首先根据NDVI分为三大类:草地、旱地和灌木林、水浇地和有林地,然后利用TM4区分旱地和灌木林,用TM5-TM4的差值把水浇地和有林地分离。精度评价结果表明,分类总精度为86.8%,Kappa系数为0.8506,达到分类要求标准。
Taking water-wind erosion region of Hengshan County in Shaanxi Province as a study area,certain information was extracted layer by layer through analyzing spectral characteristics of different land cover type by TM image and choosing different characteristic parameter and classification method: first extracting water area by TM5/Tm^3,and then dividing the other region into vegetation region and non-vegetation region by NDVI.In non-vegetation region,town land was extracted through NDBI and NDVI,and then sandy land and waste grassland were separated by TM5.While the vegetation region was divided into three classes by NDVI: grassland,dryland and shrub forest,irrigated land and forest land.Then dryland and shrub forest were separated in class 2 by TM4,irrigated land and shrub forest in class 3 by the difference of TM5-TM4.The result of accuracy evaluation showed that the overall classification accuracy is 86.8%,the Kappa coefficient is 0.8506 and they satisfied the classification accuracy standard.