Thermal imagery spectral analysis

Thermal imagery from the Spatially Enhanced Broadband Array Spectrograph System (SEBASS) was analyzed for target detection purposes. The push-broom sensor was operated as part of the WESTERN RAINBOW experiment in October 1995. Data from 7.8-13.4 microns were collected in 128 wavelength bands, with 128 pixels in the cross-track direction. The data set had a nominal ground-resolution of better than one meter. Analysis techniques normally used in the reflective domain, with traditional imaging spectrometers, were used for the thermal data. Analysis was done in both the radiance and emissivity domains, following careful thermal calibration and atmospheric compensation. The techniques utilized were principal components, spectral angle mapper, and spectral matched filter. All were successful, with the first two showing a success rate comparable to that found in similar experiments in the reflective domain. The principal components technique was successful in discriminating man-made objects and disturbed earth from the desert background, much as expected. It was also successful in distinguishing between different categories of man-made objects. Of the latter two techniques, the spectral matched filter was more successful. This relatively greater success is attributed to the sensitivity of the spectral angle mapper to calibration errors, particularly in the conversion from radiance to emissivity.