NDVI – Normalized Difference Vegetation Index
Formulas to find NDVI are:
NDVI (Landsat 8) = (B5 β B4) / (B5 + B4)
NDVI (Landsat 4 β 7) = (B4 β B3) / (B4 + B3)
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Range of NDVI is -1 to 1
-1 i.e. negative values indicate areas other than Vegetation cover, like snow, water or clouds where Red Reflectance is more than Near-Infrared.
Values close to 0 indicate bare soils with reflectance values in red and near infrared.
1 i.e. positive values which are generally between 0.1 and 0.7 means Healthy Vegetation.
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