A Study On Methods Used To Extract Alteration Information From ETM~+ And ASTER Data

Alteration information extracting from multi-spectral remote sensing image has always been a hotspot and difficulty in remote sensing geology field. After several decades of development, alteration information extraction methods, from simple qualitative, semi-quantitative to quantitative, have developed greatly, such as band ratio, principal components analysis. Besides, some new methods have been applied in Alteration information extraction, such as the spectral angle mapping, decomposition of mixed pixels, support vector machine, neural network and genetic algorithms. Band ratio and principal components analysis has become the main pattern of alteration information extraction based on TM/ETM remote sensing data. Recently, rapid progress has been made in the study of alteration information extraction using Aster data. However, previous mostly research methods often fist obtain alteration anomalies, and then be matched together in order to extract regional alteration. Additionally, remote sensing data preprocessing method also has the need to improve and perfect place .The research achievements of this paper are as follow:(1) On basis on of the summary and analysis existing anomaly extraction method, this paper successfully extracted the iron mineralization, hydroxyl and carbonate alteration with ETM data by using mask, PCA and threshold technique. From ASTER data, extraction of the iron mineralization, Al-OH, Mg-OH and carbonate 3 classes alteration information. For finding ore work to provide valuable information.(2) For radiation, atmospheric conditions, terrain conditions, different multi-view image on the regional impact of information extraction, this paper proposes first by using the FLASSH model for radiometric calibration and atmospheric correction. And then the reflection of the abnormal rate of extraction and classification, thereby ensuring the multi-view image anomalies raised by the consistency of grading.(3) On basis of summarization and analysis of the geology, structure and alteration anomalies character for the study area , combination of remote sensing imagery interpretation of a variety if information available on the anomalies are analyzed and screened .Circle successfully Cu mineralization–related anomalies 26 in the eastern Gangdise. And the abnormal area of the geological environment and mineralization conditions are analyzed. For the cold mountain area provides valuable clues.