Landsat 8 OLI data for identification of hydrothermal alteration zone in Singhbhum Shear Zone using successive band depth difference technique - a new image processing approach

摘要

Recent advances in calculation algorithms have led to a new level of image processing for mineral identification and mapping. Mineral outcrop mapping has a decade's history of using conventional methods like band combintion, band ratioing and relative absorption band depth (RBD) technique. Modification of these algorithms enriches the capabilities of object identification and mapping. Band combination and band ratioing help to locate the distribution of a hydrothermal altered zone. In the current study, an attempt has been made to modify the the RBD approach. Newly introduced successive band depth difference (SBDD) measures the difference of reflectance values in successive bands by dividing the sum of the two highest successive shoulders by the shoulder of the lowest value before the starting shoulder. Band math function has been used in various bands of Landsat 8 operational land imager (OLI) data to access the precise distribution of points of the hydrothermal altered zone. SBDD method has achieved a kappa coefficient of 0.86 which depicts significant levels of accuracy.