Obtaining surface reflectance factors from atmospheric and view angle corrected SPOT-1 HRV data

M. Susan Moran, Ray D. Jackson, Galen F. Hart, Philip N. Slater, Richard J. Bartell, Stuart F. Biggar, David I. Gellman, Richard P. Santer

Research output: Contribution to journalArticlepeer-review

50 Scopus citations


SPOT-1 High-Resolution Visible (HRV) multispectral (XS) and panchromatic data were acquired over an agricultural area on two consecutive days in June 1987, June 1988, and April 1989, at view zenith angles of approximately 23° and 10°. Digital data were converted to surface reflectance factors (ρs) by use of the sensor calibration coefficients, measurements of atmospheric optical depth, and a radiative transfer model. View-angle corrections (Cv) were derived from ground-based measurements of bidirectional radiance of bare soil, and used to convert nadir ground- and aircraft-based measurements to off-nadir values (ρg and ρa, respectively) for comparison with SPOT HRV data. The absolute error of ρs values, relative to ρg and ρa, was less than 10% for most XS bands on all six days over the reflectance range 0.1-0.4. However, there was a systematic trend for ρs estimates to be slightly higher than ρg and ρa measurements, particularly at low surface reflectances. The Cv coefficients were then applied to SPOT HRV data for a variety of cover types to assess the effectiveness of a simple, view-angle correction over a complex landscape. For rough, unvegetated surfaces, ρs values that had originally differed by more than 0.09 in reflectance on the two days were brought to within 0.01 in all three XS bands. For vegetated surfaces, Cv appeared to be wavelength dependent; the soil-based Cv worked well for data in the red and green wavebands but overcorrected the near-IR data. The Cv correction overcompensated for view angle effects over planar surfaces (i.e., water and roads) in all wavebands.

Original languageEnglish (US)
Pages (from-to)203-214
Number of pages12
JournalRemote Sensing of Environment
Issue number2-3
StatePublished - 1990

ASJC Scopus subject areas

  • Soil Science
  • Geology
  • Computers in Earth Sciences


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