Algorithms

NDRE

NDRI

NDRE uses a red edge filter to view the reflectance from the canopy of the crop. The red edge marks the boundary between absorption by chlorophyll in the red visible region, and scattering due to leaf internal structure in the NIR region. This allows you to determine many different variables with crop management. Understanding the levels of chlorophyll can provide you with the ability to monitor photosynthesis activity.

With this information you can optimize harvest times based on transitions of photosynthesis activity. During crop harvest events like: hull split in almonds or max sugar content in grapes, a noticeable change in NDRE values occur. This change occurs because sugar molecules produced from photosynthesis are no longer needed in such a high demand since the fruit/nut has reached maturity. This provides you with a crop management tool for harvest scheduling to have the highest quality produce.

Other factors that can change chlorophyll levels and cause crop stress are insect infestations. By utilizing NDRE you can determine how severe a mite outbreak is for an almond field and then use a precise way to terminate the infestation. This not only allows you to monitor outbreaks, but also reduce costs associated with pest control.

Advanced fertilization methods have become essential to agriculture due to the increased price in fertilizer/fuel and increased restrictions. GNDVI displays and values provide you with a comprehensive way to apply your fertilizer. This means that fertilizer can be applied more precisely to target the areas of interest. This not only results in an economical benefit, but also an environmental benefit.

NDVI

Crop Management Benefits

  • Canopy coverage & density detection
  • Produces accurate growth trending with frequent use
  • Frost Damage Detection
  • Large Scale Pest Outbreaks
  • Optimizing crop rotation times
  • Ecological Benefits
  • Vegetation dynamics or plant seasonal changes over time
  • Biomass production
  • Grazing management & impacts (e.g., stocking rates)
  • Changes in range land condition
  • Vegetation or land cover classification
  • Moisture content in the soil
  • Carbon sequestration or CO2 flux

NDVI

The Normalized Difference Vegetation Index (NDVI) is an indicator of plant "greenness" or photosynthetic activity, and is one of the most successful vegetation indices. Based on the observation that various surfaces reflect certain types of light differently. Photosynthetically active vegetation, absorbs most of the red light that hits it, and reflects much of the near infrared light. Dead or stressed vegetation is the opposite, it reflects more red and less near infrared light. In addition, surfaces without vegetation have a more even reflection along the light spectrum.

By using the ratio of red and near infrared bands from a remotely-sensed image, Stratus Imaging can define an index of vegetation "greenness". The normalized difference between the red and near infrared bands are calculated on a per-pixel basis from an image forming an NDVI:

 

Where NIR is the near infrared band value for a cell and RED is the red band value for the cell. NDVI can be calculated for any image that has a red and a near infrared band. The biophysical interpretation of NDVI is the fraction of absorbed photosynthetically active radiation.

GNDVI

GNDVI

The Green Normalized Difference Vegetation Index (GNDVI) is an index of plant "greenness" or photosynthetic activity. It is one of the most commonly used vegetation indices to determine water and nitrogen uptake into the crop canopy. GNDVI basically replaces the red piece of standard NDVI collection with a very specific band of light in the green range to obtain different useful information.

Water must be used effectively. Frequent GNDVI displays from Stratus Imaging allows for irrigation optimization and indicates when water isolation occurs or varies throughout the field in a glance. Using this data, along with the GPS coordinate information pinpointing the problem areas to determine solutions is very valuable and can also help provide material application, grade correction or root stock improvement to make your fields more uniform in water retention and utilization.

Water is also a main factor required for photosynthesis. Using GNDVI images you can allocate water efficiently to the areas that need it most.

  • By monitoring the proper grade of the field to improve flood row irrigation.
  • With drip irrigation, clogged lines can be found, optimizing how the drip irrigation is set up.

The GPS coordinate information used with the individual plant requirements allows for accurate variable rate spreading. This feature alone, when properly utilized, can more than pay for itself and the entire service in a single application.