There are several vegetation indices available; NDVI, MSAVI, NDRE, CCCI, TCI. This guide will walk you through what they measure and when to use each one according to the crop cycle.
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Vegetation indices in FluroSense
NDVI: Normalized difference vegetation index
Calculated using red visible light and NIR. The NDVI index reaches high values when the field is covered by healthy reflecting leaves which makes it a good indicator for plant health and biomass density.
Negative values of NDVI (i.e. -1) correspond to water. Values close to zero (-0.1 to 0.1) generally correspond to barren areas of rock or sand. Low, positive values represent shrub and grassland (0.2 to 0.4), while high values indicate temperate and tropical rainforests (values approaching 1).
MSAVI: Modified Soil Adjusted Vegetation Index.
Minimizes soil influences on canopy spectra by incorporating a variable soil adjustment to NDVI. The soil correction factor can reduce sensitivity to vegetation change and will saturate as the canopy closes over the soil. As a result, MASVI best applied when analyzing crops during the initial stages of growth.
- NDRE: Normalized Difference Red Edge
NDRE is best used when the crop is fully grown as it replaces the regular red light with the Red Edge which is sensitive to chlorophyll. Consequently, it reveals the canopy structure and nitrogen content. Complementary to NDVI as it is sensitive even with high crop biomass.
- CCCI: Canopy Chlorophyll Content Index
Most suited to late growth stages as it correlates with the plant’s nitrogen which is a major component of Chlorophyll. Combine with tissue sampling data to generate accurate N maps as it measures relative nitrogen content adjusted for biomass.
- TCI: True Colour Image
Creates a photo image of the field by combining R, G & B bands. Useful for identifying anomalies detected in other indices. Can be used to identify different soil types on bare fields or track harvest in some crops.