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# Enhanced vegetation index (EVI)

A spectral vegetation index that uses blue light to correct for NDVI inaccuracies.

## Description

EVI improves NDVI in the following ways:

• Corrects for the difference in atmospheric conditions and solar incidence angle.
• Optimizes the vegetation signal in areas with a high leaf area index (LAI).

## Use cases

• To assess biophysical properties, such as LAI.
• To assess the variability of crop development under both dense vegetation cover and sparse vegetation conditions.
• To quantify evapotranspiration or water use efficiency.
• To evaluate changes in large areas.

## How it works

EVI is calculated using red, blue, and near-infrared (NIR) bands.

It's similar to NDVI, but uses the reflection region of blue light to correct for background and atmospheric noise — for example, aerosol scattering. EVI is useful in areas with dense green vegetation, because it doesn't become as saturated as NDVI.

$\mathrm{EVI} = 2.5 * \frac{NIR - Red}{(NIR + 6 * Red - 7.5 * Blue) + 1}$

EVI ranges between -1 and 1. The healthy vegetation value is somewhere between 0.2 and 0.8.

## Limitations

• Bright areas, such as clouds and white buildings, along with dark areas, such as water, can result in anomalous pixel values in an EVI image.
• EVI requires the blue band, which limits the number of available remote sensors.
• The blue band usually has a low signal-to-noise ratio.

Use these EVI processing blocks from our marketplace: