Retrieval of surface BRDF for reflectance-based calibration

K. Thome, J. Czapla-Myers, J. Mccorkel

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Scopus citations


The University of Arizona has recently deployed a set of automated, downlooking radiometers to retrieve surface reflectance of the Railroad Valley test site in Nevada. Results from these radiometers have been combined with atmospheric data from the same site to provide a reflectance-based, vicarious calibration of multiple sensors. The accuracy of the calibrations is similar to those obtained from on-site personnel. Past work has emphasized near-nadir views by the satellite sensors under study to match more closely the view geometry of the automated radiometers to minimize the effect of bi-directional effects in the surface reflectance. Extension to off-nadir views requires an accurate understanding of the surface BRDF. Surface bi-directional reflectance effects have always played a key role in the accuracy of the vicarious calibration of imaging sensors. Such effects are especially important for the large, off-nadir views of sensors such as AVHRR and MODIS. The current work presents a method for retrieving the BRDF using the nadir-viewing data from the automated radiometers throughout the day. The concept of reciprocity is used to derive the reflectance as a function of view angle based on the measurements as a function of solar zenith angle. Comparisons of the results from this approach are compared to MODIS-derived BRDF data as well as ground-based measurements.

Original languageEnglish (US)
Title of host publicationEarth Observing Systems XII
StatePublished - 2007
EventEarth Observing Systems XII - San Diego, CA, United States
Duration: Aug 26 2007Aug 28 2007

Publication series

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


OtherEarth Observing Systems XII
Country/TerritoryUnited States
CitySan Diego, CA


  • Absolute-radiometric calibration
  • Surface BRDF
  • Vicarious calibration

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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