Characterization of geological samples of desert terrain using Hyperspectral data
Shailesh Kumar Yadav, Defence Laboratory (India)
R Vijayarahavan, Defence Laboratory (India)
R. T. Paturkar, Defence Laboratory (India)
Imaging spectrometry of geological materials is a promising technology for remote determination of mineral deposits on the surface and characterization of lithological distribution. Due to a large number of contiguous spectral bands this technology can produce three dimensional image cubes of data to evaluate spectral properties of individual surface features. Increased dimensionality of the data proves to be very useful for discriminating features with very close spectral matching. Some commonly exposed rock samples were collected from different part of desert terrain of the great Thar Desert along with GPS data. Hyperspectral data of these samples over 400nm-960nm wavelength range in 240 bands were acquired in field conditions. Simultaneously measured downwelling irradiance was used to derive reflectance data from the raw Hyperspectral data. Spectral signatures of samples were derived from the processed data. Spectral signature of each sample and derived features vectors were correlated with the satellite image of the area and distribution of each feature was demarcated. Spatial abundance of each feature was used in preparation of mineral map as well as lithological map of the study area. Accuracy of the map was assessed using training sets of representative geological units. The use of Hyperspectral data was found to be useful to arrive at the best classification procedure and subsequently achieve the best possible mapping accuracy for a given satellite data. Though the approach was used over desert terrain in this study, it can be extended to hilly terrain also.
