Model and measurements of linear mixing in thermal IR ground leaving radiance spectra

Lee Balick*, William Clodius, Christopher Jeffery, James Theiler, Matthew McCabe, Alan Gillespie, Amit Mushkin, Iryna Danilina

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

1 Scopus citations

Abstract

Hyperspectral thermal IR remote sensing is an effective tool for the detection and identification of gas plumes and solid materials. Virtually all remotely sensed thermal IR pixels are mixtures of different materials and temperatures. As sensors improve and hyperspectral thermal IR remote sensing becomes more quantitative, the concept of homogeneous pixels becomes inadequate. The contributions of the constituents to the pixel spectral ground leaving radiance are weighted by their spectral emissivities and their temperature, or more correctly, temperature distributions, because real pixels are rarely thermally homogeneous. Planck's Law defines a relationship between temperature and radiance that is strongly wavelength dependent, even for blackbodies. Spectral ground leaving radiance (GLR) from mixed pixels is temperature and wavelength dependent and the relationship between observed radiance spectra from mixed pixels and library emissivity spectra of mixtures of 'pure' materials is indirect. A simple model of linear mixing of subpixel radiance as a function of material type, the temperature distribution of each material and the abundance of the material within a pixel is presented. The model indicates that, qualitatively and given normal environmental temperature variability, spectral features remain observable in mixtures as long as the material occupies more than roughly 10% of the pixel. Field measurements of known targets made on the ground and by an airborne sensor are presented here and serve as a reality check on the model. Target spectral GLR from mixtures as a function of temperature distribution and abundance within the pixel at day and night are presented and compare well qualitatively with model output.

Original languageEnglish (US)
Title of host publicationRemote Sensing for Environmental Monitoring, GIS Applications, and Geology VII
DOIs
StatePublished - Dec 1 2007
EventRemote Sensing for Environmental Monitoring, GIS Applications, and Geology VII - Florence, Italy
Duration: Sep 17 2007Sep 20 2007

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume6749
ISSN (Print)0277-786X

Other

OtherRemote Sensing for Environmental Monitoring, GIS Applications, and Geology VII
CountryItaly
CityFlorence
Period09/17/0709/20/07

Keywords

  • Thermal infrared emissivity spectra remote sensing

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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