TY - JOUR
T1 - Normalization of multidirectional red and NIR reflectances with the SAVI
AU - Huete, A. R.
AU - Hua, G.
AU - Qi, J.
AU - Chehbouni, A.
AU - van Leeuwen, W. J.D.
N1 - Funding Information:
We thank Dr. Ray Jackson of the U.S. Water Conservation Lab, Phoenix, Arizona for lending us the BRF apparatus for the entire summer field campaign. This study was supported by the Land Processes Branch of NASA under Project NAWG-1949 and by MODIS Team Member Grant NAS 530789.
PY - 1992
Y1 - 1992
N2 - Directional reflectance measurements were made over a semidesert gramma (Bouteloua spp.) grassland at various times of the growing season. Azimuthal strings of view angle measurements from + 40° to - 40° were made for various solar zenith angles and soil moisture conditions. The sensitivity of the normalized difference vegetation index (NDVI) and the soil-adjusted vegetation index (SAVI) to these bidirectional measurements was assessed for purposes of improving remote temporal monitoring of vegetation activity. The NDVI response from the grassland canopy was strongly anisotropic about nadir view angles while the SAVI response was symmetric about nadir. This occurred for all sun angles, soil moisture condition, and grass densities. This enabled variations in SAVI-view angle response to be minimized with a cosine function. It is expected that this study will aid in improving the characterization of vegetation temporal activity from Landsat TM, SPOT, AVHRR, and the Earth Observing System MODIS sensor.
AB - Directional reflectance measurements were made over a semidesert gramma (Bouteloua spp.) grassland at various times of the growing season. Azimuthal strings of view angle measurements from + 40° to - 40° were made for various solar zenith angles and soil moisture conditions. The sensitivity of the normalized difference vegetation index (NDVI) and the soil-adjusted vegetation index (SAVI) to these bidirectional measurements was assessed for purposes of improving remote temporal monitoring of vegetation activity. The NDVI response from the grassland canopy was strongly anisotropic about nadir view angles while the SAVI response was symmetric about nadir. This occurred for all sun angles, soil moisture condition, and grass densities. This enabled variations in SAVI-view angle response to be minimized with a cosine function. It is expected that this study will aid in improving the characterization of vegetation temporal activity from Landsat TM, SPOT, AVHRR, and the Earth Observing System MODIS sensor.
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U2 - 10.1016/0034-4257(92)90074-T
DO - 10.1016/0034-4257(92)90074-T
M3 - Article
AN - SCOPUS:0027010138
SN - 0034-4257
VL - 41
SP - 143
EP - 154
JO - Remote Sensing of Environment
JF - Remote Sensing of Environment
IS - 2-3
ER -