(VARI Visible Atmospherically Resistant Index)

Visible Atmospherically Resistant Index (VARI) is a way of measuring the amount and health of vegetation using only the visible range of the spectrum. It is calculated by comparing the amount of green light (which vegetation reflects strongly) and red and blue light (which vegetation absorbs) that is reflected by the land cover. VARI values range from -1 to +1, where higher values indicate more green and healthy vegetation, and lower values indicate less or no vegetation.

VARI = (Green - Red) / (Green + Red - Blue)