An alternative approach, as suggested by Cohen et al.(2003), is to couple more spectral vegetation indices from multiple dates into the regression analysis. They claimed that using a single index which integrated from the multiple
indices by canonical correlation analysis represents a significant strategic improvement over regressions solely dependent on a single vegetation index. Since global remote sensing data archives are expanding with more and more spectral information besides the NDVI data set, the approach of Cohen et al. (2003) could be useful for estimating LAI at regional and global scales.