What is a Vegetation Index?

A Vegetation Index (VI) is a spectral calculation that is done between two or more bands of the source data designed to enhance the contribution of vegetation properties and allow for comparisons of photosynthetic activity across your area of interest.


When the VI calculation takes place, it goes pixel by pixel through your entire dataset and runs a calculation on the spectral values of that pixel. This will assign a value representing some version of plant health for each pixel in the image. These values are then generalized to different ranges and turned into the colorized map you see on screen when the calculation is complete.


VI’s allow you to see relative differences in the general plant health across your entire field. Because these are relative differences in plant health across your field it is important to apply only to the areas you are interested in. For an example if you include a gravel road in the bounds of your vegetation index run the lower side of your VI range is going to be thrown off by this non living material included in your area of interest.


The methodology behind these calculations are slightly different for each VI that we offer. Below we have reviewed each Vegetation Index applicable to Multispectral data in PrecisionMapper (BGNIR,and RGNIR).




Vegetation Indices for Multispectral Data

In PrecisionMapper we accept two types of Multispectral data for Vegetation Index application- BGNIR and RGNIR. 


Healthy vegetation will absorb more Blue and Red light to fuel photosynthesis and create chlorophyll in the plant. A plant with more chlorophyll will reflect more NIR energy than an unhealthy plant. Thus, by comparing the absorption of this blue and red light to the reflectance of the NIR wavelength we are able to provide valid information about a plants health. 




BGNIR



Supported Sensors
BGNIR
Supported Resolution
20 cm/pixel or less
Other Requirements
NA
Estimated Processing Time
2 Hours or less
Outputs    
Georeferenced Image, PDF Map, KML




RGNIR



Supported Sensors
RGNIR
Supported Resolution
20 cm/pixel or less
Other Requirements
NA
Estimated Processing Time
2 Hours or less
Outputs    
Georeferenced Image, PDF Map, KML