Estimation of crown cover fraction and recovery of background information

Crown cover fraction is an important ecological and environmental parameter. In this paper, an algorithm to estimate crown cover fraction is derived according to the characteristics of soil and vegetation spectra and the definition of crown cover fraction. Furthermore, a more simple method, which is called maximal gradient difference method, is proposed to calculate crown cover fraction. Once the crown cover fraction is calculated, the background spectra of pixels that are partly covered by vegetation can be recovered under the assumption of linear spectra mixing. Using the above method, we´ve successfully retrieved the background information of a TM image of Colorado State. The method we proposed is simple, easy to performance, and can separate the effect of soil and vegetation effectively, so it´s possible to replace the method of estimating crown cover fraction from NDVI, which is used widely at present.