本文选取了一年中三个不同时相的TM影像,分别求出了三幅影像的NDVI分布图,将其合成为一幅影像图。由于不同区域种植的作物在三个时相中的NDVI变化是不同的,因此在NDVI合成图上会呈现不同的颜色区域。通过对不同颜色区域进行采样分析,可以确定桃红色区域为冬小麦、玉米(大豆)轮作区,蓝紫色区域为棉花、春玉米、杂粮种植区,亮蓝区域为水稻种植区,亮绿色区域为林地、草地。最后,根据不同颜色区域的NDVI变化特征用非监督分类和监督分类相结合的方法对影像进行了分类提取。这样便可对黄河三角洲农作物的种植情况进行宏观的了解,为农作物种植合理布局及农业可持续发展提供依据。

Agriculture plays an important and basic role in the Yellow River Delta It is quite essential for agricultural managers to understand the information on allocation of crop production as a whole The traditional way of obtaining the information on crop allocation is the statistical or investigation method Compares to the traditional method, the remote sensing techniques have the advantages of quickness, precision and visualization in providing the information of crop production There are also difficulties for remote sensing to discriminate different crop areas because all the crops have similar spectrum curves on the remote sensing images To solve this problem, in this paper three remote sensing images of the Yellow River Delta at different stages of a year are used, and three NDVI maps are obtained based on the images respectively which are combined into one NDVI image Because the NDVI varieties of crops planted in different fields are different during the year, there will be different regions which show different colors on the combined image Samples from different color regions are analysed and it can be confirmed that the red area in the combined image is the region where winter wheat, corn and soybean are planted, the purple area is the region where cotton, spring corn and other crops are planted, the light blue area is the region where rice is planted and the light green area is the region where forest and grass are planted According to the characteristics of NDVI in different color areas the combined NDVI image is classified using unsupervised classification method and supervised classification method Finally the classification result is analysed Through this research we can understand the crop planting system of the Yellow River Delta macroscopically, and can provide service for the sustainable development of agriculture in the Yellow River Delta