其次，利用TM影像的第四和第三波段计算植被指数，根据植被指数按照转换模型提取植被覆盖度；

Next, vegetation index was calculated which was based on Band 3 and Band 4 of TM image, and degree of vegetation coverage was extracted according to NDVI based on the transformation model;

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土地植被覆盖指数的准确度取决于图像分类准确度，但与分类总准确度没有直接关系。

The accuracy of land vegetative cover index rested with the accuracy of image classification, but had no direct relations with total classification accuracy.

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