Remote Sensing in Agriculture (Normalized Difference Vegetation Index-NDVI)

Author: Mariam Tsitsagi
Keywords: NDVI, Remote Sensing
Annotation:

Agricultural scientists have used remote sensing for hundreds of years to observe plants to assess their vigor or stress from a multitude of factors. These original observations were not made with sensors but with the eye that determined the health of the plant.Jackson and Huete (1991) classify VIs into two groups: (1) slope-based and (2) distance-based VIs. Slope-based VIs are combinations of the visible red and the near infrared bands and are widely used to generate vegetation indices. Their values indicate both the state and abundance of green vegetation cover and biomass. The slope-based VIs include the RATIO, NDVI, SAVI, RVI, NRVI, TVI, CTVI, TTVI, and EVI. The normalized difference vegetation index (NDVI) is a simple graphical indicator that can be used to analyze remote sensing measurements, typically but not necessarily from a space platform, and assess whether the target being observed contains live green vegetation or not. NDVI is calculated from the visible and near-infrared light reflected by vegetation. Healthy vegetation (left) absorbs most of the visible light that hits it, and reflects a large portion of the near-infrared light. Unhealthy or sparse vegetation (right) reflects more visible light and less near-infrared light. The numbers on the figure above are representative of actual values, but real vegetation is much more varied.