The most popular method of vegetation analysis uses the Normalized Difference Vegetation Index (NDVI) algorithm to measure plant material. NDVI is used to measure and monitor plant growth, vegetation cover and biomass production using any multispectral sensor which has both a Visible Red and Near Infra-Red bands.
The algorithm formula is: (Near Infra-Red – Visible Red) / (Near Infra-Red + Visible Red)
Examples of satellite sensors which incorporate the above bands include: Landsat, ASTER, ALOS, Quickbird, GeoEye 1 and Worldview 2.
Worldview 2 natural colour imagery captured over agricultural area in NSW, Australia. Vegetation appears as green; however differences in plant health are not very accurate.
False colour processed image of the same area. Here, the brighter reds highlight more vigorous and healthy plant growth. Although better than the natural colour image, once again the subtle differences are not obvious.
NDVI processed image of the same area shows not only the extent of vegetation health, but also density. Due to the incorporation of better band widths in between the Red and Near Infra-Red spectrum zones, the Worldview 2 satellite is better suited to vegetation analysis compared to precursor sensors.
