Influence of the Different Spatial Resolutions for Alteration Mineral Mapping

Vein-type alterations are extensively distributed and normally very thin,the extraction of these alteration zones is affected by the spatial resolution of remote sensing data seriously. To evaluate the ability of different spatial resolutions for alteration mineral mapping,taking Jintanzi area as the study area,the pixel of airborne CASI/SASI hyperspectral data were resampled to 5 m,10 m,15 m,20 m and 30 m. The spectrum of muscovite from JPL spectral library and matched filtering method were utilized to extract the distribution of muscovite minerals. Spectra of pixels show that for alteration of large areas the spectral features are influenced weakly by the changing of spatial resolution and all the absorption features could be retained. Comparably,for the thin vein-type alteration,with the degradation of spatial resolution,the effect of the mixed pixel is more serious.Thus,the absorption feature of image spectra is very shallow. When the spatial resolution is 30 m,the absorption is weakest and difficult to be identified. The mapping results of the muscovite show that the thin vein-type alteration(about 1 to 5 meters wide)could be identified in the images with resolution of 5 m,10 m and 15 m,while it is difficult for the images with resolution of 20 m and 30 m to detect.