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