Vegetation Indices

What is a Vegetation Index (VI)?

 

Vegetation Index is a single value calculated by transforming the observations from multiple spectral bands. It is used to enhance the presence of green, vegetation features and thus help to distinguish them from the other objects present in the image. Depending on the transformation method and the spectral bands used, different aspects pertaining to the vegetation cover in the image could be evaluated say, the percentage of vegetation cover, amount of chlorophyll content, leaf area index and so on.

 

All the ratio indexes, in general, are independent of the illumination conditions at the time of acquisition and slope effects.

 

Why is Chlorophyll monitoring important?

 

Chlorophyll is the green pigment present in the leaves and plays an important role in photosynthesis i.e. conversion of light energy to chemical energy. Hence, it is a direct indicator of the plant’s primary production and photosynthetic potential. It can be also used to understand the plant’s nutrient status, senescence and stress due to water, disease outbreak, etc.

Several indices have been developed to estimate the vegetation cover and chlorophyll content of the leaves as follows:

 

Vegetation Indices

Chlorophyll Indicators