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Investigation of information contained in spectral hull and absorption feature of hyperspectral data for geological remote sensing

Gebremeskel, Ambasager Tetemke (2010) Investigation of information contained in spectral hull and absorption feature of hyperspectral data for geological remote sensing.

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Abstract:Absorption features in reflectance spectra of hyperspectral data in visible to near infrared (VNIR) and short wave infrared (SWIR) wavelength region have been used as source of information for surface mineralogical identification and mapping. This becomes possible because there is a direct relation between absorption features in a spectrum and minerals. The continuum component of spectrum which is called spectral hull is often removed from the spectrum before any subsequent analysis of absorption features. In this research an investigation of information contained in spectral hulls of altered volcanic, carbonate and unaltered volcanic rocks of Rodalquilar area which is southeast of Spain is carried out. Based on similarity of spectra, rocks found in the study area were classified in to three classes: altered volcanic, unaltered volcanic and carbonate classes. Spectral hulls of altered volcanic, carbonate and unaltered volcanic classes have been studied systematically by setting different parameters. Subsequently the altered volcanic, carbonate and unaltered volcanic classes have been identified using shape of their spectral hulls derived from field spectral data. From field spectral data the investigation was up scaled to HyMAP hyperspectral image with 126 bands and 4m spatial resolution. Through careful analysis of continuum hull image (contains only spectral hull information) derived from the HyMAP image, it was possible to identify and map altered volcanic, carbonate and unaltered volcanic classes using spectral angle mapper technique. For comparison of information in the form of absorption feature and information contained in spectral hull, mineral map was done using information in the form of absorption feature. The comparison was done by calculating confusion matrix between the three lithological classes of classified continuum hull image and mineralogical classes of classified continuum removed image. The result showed a good matching between minerals and lithological classes. The degree of matching shows that information contained in spectral hull can help in understanding of mineral maps. The information obtained from spectral hull can not be used to subdivide lithologies with in unaltered volcanic class. Influences of grain size, viewing geometry (bidirectional reflectance distribution function), vegetation and soil on shape of spectral hull were tested. The test showed that adding 30% of spectral hull of vegetation and 20% of spectral hull of soil strongly affects the shape of spectral hull of the three lithological classes.
Item Type:Essay (Master)
Faculty:ITC: Faculty of Geo-information Science and Earth Observation
Programme:Geoinformation Science and Earth Observation MSc (75014)
Link to this item:https://purl.utwente.nl/essays/92525
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