Multispectral Imaging

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NDVI

Is an index of plant photosynthetic activity, and is one of the most commonly used vegetation indices. Vegetation indices are based on the observation that different surfaces reflect different types of light differently. Photosynthetically active vegetation, 

absorbs most of the red light that hits it while reflecting much of the near infrared light. Vegetation that is dead or stressed reflects more red light and less near infrared light. Likewise, non-vegetated surfaces have a much more even reflectance across the  light spectrum.

 The NDVI ranges from 1 to -1, with higher values indicating greater plant vigour

Uses: plant vigor, differences in soil water availability, foliar nutrient content, 

yield potential

NDRE

Is an index that can only be formulated when the Red edge band is available in a sensor. It is sensitive to chlorophyll content in leaves (how green a leaf appears), variability in leaf area, and soil background effects. High values of NDRE represent higher levels of leaf chlorophyll content than lower values. Soil typically has the lowest values, 

unhealthy plants have intermediate values, and healthy plants have the highest values.

The NDRE ranges from 1 to -1, with higher values indicating greater plant vigour

Uses: leaf chlorophyll content, plant vigor, stress detection, fertilizer demand, 

Nitrogen uptake

CWSI

 Crop Water Stress Index (CWSI) is a method used to assess and quantify the water stress levels in crops. It is a valuable tool for farmers, agronomists, and researchers to monitor and manage irrigation practices effectively. CWSI is based on the principle that plants respond to water stress by adjusting their stomatal conductance, which affects the exchange of water vapor between the plant and the atmosphere. 

 The CWSI is an indicator of the crop's water status, helping farmers determine when and how much irrigation water should be applied. By regularly monitoring CWSI, farmers can optimize irrigation scheduling, prevent overwatering or underwatering, and reduce water usage while maintaining crop health and productivity. 

 The CWSI ranges from 0 to 1, with higher values indicating greater water stress