Authors : Adama Ouattara, Bruce E. Frazier and Abdourahamane Konare
Abstract: First-order soil brightness effects are accounted for with orthogonal indices and Soil Adjusted Vegetation Indices (SAVI) and particularly true at very low Leaf Area Indices (LAI). However, they have limited dynamic range and they fail to account for residual soil brightness effects observed at intermediate LAI. The objective of the study is to devise an index from existing ones that would overcome these shortfalls. First, a graphical method is shown to give a general formulation for the orthogonal vegetation indices (i.e., ADVI). Then, from the analysis of ADVI, it is shown that ratio and orthogonal are functionally equivalent under certain conditions. Finally, by combining ADVI and SAVI, the new hybrid index (HYBRID) obtained is the least affected by soil brightness effects at all LAI values, has the greatest dynamic range, is the most sensitive to LAI changes, saturates at very high LAI and seems to evolve linearly with LAI.
Adama Ouattara, Bruce E. Frazier and Abdourahamane Konare, 2009. A New Enhanced Soil Adjusted Vegetation Index: HYBRID. Online Journal of Earth Sciences, 3: 40-45.