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旨在利用宽范围动态植被指数对棉花冠层覆盖度进行监测,解决传统的利用归一化差值植被指数对冠层覆盖度较高时监测不准确(饱和)的问题。采用高光谱仪获取棉花不同时期不同覆盖度的冠层光谱反射率,通过对构成归一化差值植被指数的近红外波段反射率引入系数α来提高修正后的植被指数随棉花覆盖度变化的动态范围。当利用权重系数0.1≤α≤0.2对近红外波段反射率调整之后,新形成的宽范围动态植被指数用于监测不同覆盖度棉花时未出现“饱和”现象。利用宽范围动态植被指数建立的棉花覆盖度监测模型的决定系数r2>0.948,对棉花冠层覆盖度进行监测,可以解决传统的归一化差值植被指数对冠层覆盖度较高时监测不准确(饱和)的问题,提高了植被指数对棉花冠层覆盖度监测的精度。
The aim is to monitor the cotton canopy coverage with a wide range of dynamic vegetation index and to solve the problem of inaccurate (saturation) monitoring when the canopy coverage is high with the traditional differential vegetation index. The spectral reflectance of canopy at different coverage of cotton was obtained by hyperspectral spectroscopy, and the coefficient of α was introduced into the reflectance of the near-infrared (IR) band which constituted the normalized difference vegetation index to improve the dynamic state of the modified vegetation index with the change of cotton coverage range. When using the weight coefficient of 0.1≤α≤0.2 to adjust the reflectivity of the near infrared band, the newly formed wide dynamic range vegetation index is not used to monitor the phenomenon of “saturation ” when monitoring cotton with different coverage. The coefficient of determination r2> 0.948 for the cotton coverage monitoring model established by the dynamic range vegetation index can monitor the canopy coverage of cotton and can solve the problem that the traditional normalized difference vegetation index Accurate (saturated) problems, improve the accuracy of vegetation index monitoring of cotton canopy coverage.