ENVIRONMENTAL MAPPING WITH HYPERSPECTRAL IMAGERY

Hyperspectral imaging provides new information about environmental and geologic conditions across open terrain, urban landscapes, industrial facilities, and brownfields. Sensors that record signatures of reflected light spanning visible through near-infrared to shortwave-infrared wavelengths (VNIR-SWIR) are particularly useful for earth scientists. The reflected light is subdivided into 100 to 200+ discrete samples or wavelength bands within each pixel, generating a data cube. Within each pixel, the amount of recorded energy varies across the wavelength spectrum because different materials scatter or absorb solar energy in varying amounts based on the material's physical properties and composition. Hyperspectral sensors are unique in that they have enough spectral resolution to identify different surface materials based solely on the spectral signature. Earth scientists can use VNIR-SWIR data cubes to map the characteristics of soils, including the surface distribution of clays (kaolinite, montmorillonite, illite, chlorite, etc.), iron oxides (hematite, goethite, jasperite), calcite, dolomite, and other minerals. Key environmental indicators such as vegetation stress, plant communities, surface water conditions, and land use can also be derived from data cubes. Maps of natural hazards and structural geology are improved by integration of derived maps and enhanced images with DEM's. Recently we completed a new VNIR-SWIR spectral library for detecting oil-impacted soils and surfaces (including onshore oil seeps). A cooperative R&D effort coordinated by The Geosat Committee, Inc. and sponsored by progressive petroleum companies enabled the library to be built. With this library, VNIR-SWIR hyperspectral technology can be more effectively applied to detect oil-impacted soils and surfaces within industrial sites and brownfields. Major advances are being made to minimize the cartographic error associated with airborne imaging systems. These advances will enable earth scientists and engineers to more confidently use these data-rich cubes for map-making and GIS applications.