Application And Research Of Lithologic Interpretation Of Multivariate Remote Sensing Date In Hihg Aititude Area

High altitude area has always been the focus of geological survey and engineering application.However,due to the large slope,high vegetation coverage and large snow and ice coverage,the whole area of high altitude area is difficult to be surveyed on site,with poor geophysical exploration conditions and unable to carry out accurate lithologic boundary.With the rapid development of remote sensing technology and spectroscopy and the diversified development of remote sensing data,it is possible to interpret remote sensing lithology in high altitude areas.The rock mass has unique spectral and reflectance characteristics.Through the analysis of the spectral and reflectance characteristics of the rock mass,remote sensing technology is used as the basis to solve the problem of lithologic boundary,so as to achieve the purpose of lithologic interpretation in high-altitude areas.This paper mainly selects the Bomi Nujiang bridge section of Tibet as the research area,and uses Landsat 8,aster and other multispectral data,F2 high-resolution data,GF5 hyperspectral data to extract and boundary the lithology of this area.The main research results and contents are as follows:(1)The preprocessing of remote sensing data,through radiometric calibration,atmospheric correction and geometric precision correction,can eliminate the errors caused by sensor collection and the impact of aerosols and atmospheric clouds.Through band operation and OIF(optimal band combination)method,data pixels are extracted,and the most suitable band combination mode for lithology interpretation is obtained by comparing various remote sensing data.Using GF2 data,texture information of rock mass is extracted by texture recognition and image fusion.(2)For information enhancement,MNF transform(minimum noise separation method)and PCA transform(principal component analysis)are used to reduce the dimension of remote sensing data,and the key spectral information of remote sensing data is retained and extracted.It is found that MNF transform is effective in the application of hyperspectral data,while PCA transform is more suitable for multispectral data.The standard spectral database of hyperspectral spectral information comparison is extracted by the end element extraction method,and the typical lithologic spectral database of the study area is used to assist in verifying the lithologic interpretation results of multispectral and hyperspectral.(3)Based on the field survey of the study area,the typical rock spectrum database is established by collecting typical rocks.Combined with remote sensing image and comprehensive interpretation of geological data,a more accurate division of strata and lithology is made,and a remote sensing lithology interpretation map of 1:50000 in the study area is completed.(4)By using hyperspectral data and high-quality multispectral data,combined with the results of comprehensive visual interpretation and field exploration,typical lithologic training samples are selected,lithologic mapping and mineral mapping are carried out through supervision classification,and the suitable supervision classification methods are selected by comparison.The results of comprehensive supervision classification are interpreted and corrected,and the accuracy of supervision classification is checked.This research work summarizes and analyzes the processing methods of various remote sensing data,including radiometric calibration,atmospheric correction,resampling and other methods.Based on multi spectrum,hyperspectral and high-resolution data,the lithologic interpretation of the high-altitude area from Nujiang bridge to Bomi section is carried out,and the region difficult to survey and the original lithologic boundary are revised.In this study,the method of automatic lithology and mineral mapping by multi data supervision classification and multi methods is adopted.In order to explore the appropriate supervision classification method of various data lithology interpretation,the lithology boundary check is completed at the same time.It provides a solution for the interpretation of remote sensing lithology in high-altitude area,which has a certain guiding significance for the processing of all kinds of remote sensing data and the automatic recognition of information enhancement.