A method for generating a supplementary index raster file based on a plurality of primary index raster files that are associated with an area of interest (AOI) uses a computer coupled to a remote sensing device via a network, wherein the computer includes an input device, a display, and a memory. The method includes generating the plurality of primary index raster files including at least two independent vegetation index (VI) raster files and a soil brightness index (SBI) raster file, wherein each primary index raster file includes a plurality of pixel values. The method also includes combining the at least two VI raster files to generate a classified soil brightness (CSB) raster file, classifying each pixel value of the CSB raster file into one of a plurality of classes, storing the CSB raster file into the memory, and displaying the CSB raster file.