Hyperspectral Remote Sensing

The term hyperspectral is used to refer to spectra consisting of large number of narrow, contiguously spaced spectral bands. In the field of remote sensing, the term hyperspectral is also used interchangeably with other terms such as spectroscopy, spectrometry, spectroradiometry and rarely ultraspectral. Spectroscopy is a branch of physics concerned with the production, transmission, measurement and interpretation of electromagnetic spectra. Spectrometry or spectroradiometry is the measure of photons as a function of wavelength. Ultraspectral is beyond hyperspectral, a goal that has not been achieved yet. Spectrometers are used in laboratories, field, aircraft or satellites to measure the reflectance spectra of natural surfaces. When an image is constructed from an imaging spectrometer that records the spectra for contiguous image pixels, the terms shift to become imaging spectroscopy, imaging spectrometry or hyperspectral imaging. Hyperspectral imaging is a new technique for obtaining a spectrum in each position of a large array of spatial positions so that any one spectral wavelength can be used to make a recognizable image (Clark, 1999). By analyzing the spectral features in each pixel, and thus specific chemical bonds in materials, we can spatially map materials. The narrow spectral channels that constitute hyperspectral sensors enable the detection of small spectral features that might otherwise be masked within the broader bands of multi-spectral scanner systems. In this regard, we hypothesis that hyperspectral sensors could help to overcome the traditional problems faced when using the broader bands of multispectral scanner systems, such as the saturation problem in estimating quantity and the estimation of quality.