ASTER Mineral Ratios tool (ENVI Classic)

This is a simple user function that calculates mineral indices using band ratios from ASTER VNIR, SWIR, and TIR bands. The user function assumes that all 14 spectral bands (not including the 3B band) are present in a single file and resampled to a single pixel size (layer stacked). Ideally, the ASTER data should be orthorectified and calibrated to reflectance for best results. 

Since ENVI version 4.2 , calibrating ASTER data to radiance is not necessary since ENVI applies the embedded scale factors automatically when the file is opened. If ASTER 1A data is used, registration or orthorectification is necessary prior to layer stacking the bands. If ASTER 1B data is used, orthorectification is not necessary but may be desirable to improve positional accuracy. 

Place the file, aster_mineral_ratios.sav, in the save_add directory of your ENVI installation. The user function will place a button at the bottom of the Transform menu. 

The ASTER mineral indices are based on the information presented by Geoscience Australia. http://www.ga.gov.au/ausgeonews/ausgeonews200606/aster.jsp http://www.ga.gov.au/image_cache/GA7833.pdf