Digital Imaging and Remote Sensing Laboratory: Areas of Research

Information in Hyperspectral Imagery

Sensors that collect multichannel, contiguous, narrow spectral band imagery spanning from the visible to the infrared portion of the electromagnetic spectrum are generally referred to as hyperspectral sensors. Ultraspectral imaging shares this definition with the exception that the bands are extremely narrow; on the order of 1-2nm in the visible and near-infrared. Multispectral imagery is typically tens of nanometers wide and are not necessarily contiguous. The Modular Imaging Spectrometer Instrument (MISI) is a line-scanning type hyperspectral sensor with 72 channels from 0.4痠 to 1.018痠 with 0.010痠 bandwidth each. The MISI also includes 5 multi-spectral channels in the long-wave infrared (8-14痠 (2), 8-10痠, 10-12痠, and 12-14痠) and 2 broad-band visible wavelength channels. The AVIRIS operated by JPL is another good example of a hyperspectral imager with 224 spectral bands, each with a 10nm bandwidth, and covering the spectral range of 0.4 to 2.4痠.

The power of the hyperspectral sensor lies in its ability to record a fine spectral resolution electromagnetic profile for each pixel within its field of view. Wavelength dependent characteristics in the reflectance or absorption spectra reveal important information about the chemical make-up and types of atomic and molecular bonding in the material being targeted (Goetz, 1985). Spectral features are the direct result of electronic and/or vibratory orbital energy transitions at the atomic and/or molecular level due to photon absorption. Thus, the combination, placement, and relative strength of the absorption feature(s) can be exploited for surface material identification, evaluation, and analysis of internal processes.

For more information, see this hyperspectral links page.

Refererence:

Goetz, A.F.H., Vane, G., Solomon, J.E., Rock, B.N., "Imaging Spectrometry for Earth Remote Sensing", Science, 228, no 4704, pp. 1147-1153, (1985).

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An AVIRIS Image Cube Which Shows Spatial and Spectral Dimensions.

Aerial Spectral Sampling of an AVIRIS Scene Showing the Ground Field of View, Spectral Pixel Samples, and Sample Spectrum.