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USGS Digital Spectral Library

April 9, 2017
Example spectral measurements
Example spectra plot from the USGS Spectral Library.

The USGS has assembled a library of spectra measured with laboratory, field, and airborne spectrometers. Laboratory samples of specific minerals, plants, chemical compounds, and manmade materials were measured. In many cases, samples were purified, so that unique spectral features of a material can be related to its chemical structure. These spectro-chemical links are important for interpreting remotely sensed data collected in the field or from an aircraft or spacecraft. This library also contains physically constructed as well as mathematically computed mixtures.

This interactive website allows user to search the contents of the library. Spectra are provided in ASCII data files (with .txt extension). The HTML-formatted metadata descriptions are also provided as text files with .html extension. Plots of the spectra were created and stored as GIF images with .gif extension.  For each spectrum, a zip file containing the ASCII, HTML, and GIF files can be downloaded (see the “Zip” link in the far-right column). The zip files also contain the associated wavelength and bandpass data, which are stored in separate files.

In addition to the original measured spectra, the library also includes convolved and resampled versions of spectra for selected laboratory spectrometers (ASD), imaging spectrometers (AVIRIS-Classic, HyMap, Hyperion, CRISM, M3, and VIMS), and broad band multispectral sensors (ASTER, Landsat8 OLI, Sentinel-2 MSI, and WorldView-3). See the links and drop-down selections in the black menu bar at the top of the page.

Spectra were divided into sub-categories (described as library chapters) by material type:

  • Minerals
  • Soils and mineral mixtures
  • Coatings
  • Liquids
  • Organic compounds
  • Artificial materials
  • Vegetation and other biologic materials
  • Wavelength and Bandpass
field and laboratory measurements
Collection of field and laboratory measurements for the USGS Spectral Library. Photographs by USGS.