Enhancement of thematic mapper satellite images for geological mapping of the Cho Dien area, Northern Vietnam

Abstract

Information available from the earth science image processing package (ESIPP) software program was applied to enhance the satellite image data of the Cho Dien area, northern Vietnam. The area with dense vegetation covers is dominated by several small Zn-Pb prospects in middle Paleozoic limestone units. Interpretation of satellite image data using the digital enhancement ESIPP program, forms the prime objective of this study, which is to improve the image quality and visual interpretation of regional geology, lineament and structural geology. Thematic mapper of bands 7, 5 and 4 with the false-color composites: blue, green and red, respectively, are considered to be the most appropriate for geologic interpretation. Dark pixel correction is carried out prior to other enhancement analyses which include high-pass filtering, albedo correction, image classification, principle component analysis (PCA) and band ratios. High-pass filtering enhancement is considered to be the most suitable approach for lineament analysis. Albedo is good for differentiating lithology, and image classification is also successfully used for lineament interpretation and discrimination of lithologies but is regarded not better than high-pass filtering and albedo. PCA and ratio of band enhancements are considered not good because there are many disturbed and excavated land areas such as abandoned and current open pits in the concerned area. The result of Landsat interpretation indicate that most lineament structures developed in a roughly N-trending anticlinal structure are in NE-, E- and N-trends. Minor lineaments are in roughly NW-trend, and cross-cutting the NE- and E-trends. Interpretation from enhanced Landsat information also fits very well with field evidences. The interpreted map is slightly different from those of the previous mapping works, particularly with respect to detailed lithological boundaries. © 2002 Elsevier Science B.V. All rights reserved.