What is NDVI? - Understanding Vegetation Health Index

NDVI (Normalized Difference Vegetation Index) is a vegetation index calculated from the reflectance data of the canopy. It's used to measure the health and density of vegetation by comparing the amount of light reflected in the red and near-infrared regions of the electromagnetic spectrum. The index ranges from -1 to 1, with higher values indicating healthier and denser vegetation. Therefore, NDVI is not the reflection data of the canopy itself, but rather a derived index that uses the reflectance data of the canopy.