The emissivity was assigned to be 0.97 at NDVI <0.2, and 0.99 at NDVI >0.5. When 0.2
≤ NDVI ≤ 0.5, the emissivity was calculated by the following formula:
e = 0.004 [(NDVI - NDVImin) / (NDVImax - NDVImin)]2 + 0.986
Here in equation NDVImax and NDVImin were taken as 0.50 and 0.2 respectively and NDVI
derived for his study area.

GVF = (NDVI - NDVImin) / (NDVImax - NDVImin)