The Effect of ASTER Data Calibration on Enhancing Lithological Units; a Case Study Neyriz Ophiolite Complex

Various atmospheric correction algorithms were performed on ASTER L1B VNIR SWIR datasets, and the results were compared with calibrated AST-07 dataset to introduce the best method. Neyriz ophiolite was chosen as a test area for this purpose. ASTER VNIR SWIR datasets were calibrated to apparent reflectance using two techniques: 1-Absolute atmospheric correction methods including ATCOR-2 (Atmospheric correction), ATCOR-3 (Atmospheric and Topographic correction); 2- Relative atmospheric correction methods that included IARR (Internal Average Relative Reflectance), FF (Flat Field), EL (Empirical Line), LR (Log Residuals), DOS (Dark Object Subtraction), AR (Apparent Reflectance) and COS (t). Results were evaluated by principal components analysis (Image-based algorithm) and spectral angle mapping (spectrum-based algorithm). Field spectra were used as end-members and confusion matrix was used for comparing the results of spectral angle mapping. Results of calibrated images showed that applied methods could be ranked in descending order according to the achieved accuracy of enhancing rock units as ATCOR-3, AST-07، IARR، LR, SWIR data set (L1B) and other methods had low accuracy for enhancing rock units.