Why Use Modified RGB and Multispectral Cameras and the NDVI Algorithm?
Growers, agronomists, and drone service providers (DSPs) who are seeking to understand comparative plant health data over time may wish to use NDVI imagery captured using RGB cameras that are modified with an NIR filter, or use Multispectral cameras. These cameras are specifically designed for agricultural needs. This means that any NDVI images produced are better suited to analyze and detect the smallest amount of crop stress by reading the near-infrared light and picking up on any reflection from plants. Sometimes it can be possible to identify crop issues a few days earlier than with standard RGB sensors.
What is False-NDVI?
In your research, you may have come across the term “false-NDVI.” This refers to the NDVI algorithm applied to RGB imagery. While some growers may find false-NDVI useful, we don’t recommend applying NDVI to RGB imagery because the algorithm was not designed for that purpose. As a result, this results in the reporting of inaccurate data. As mentioned above, the VARI formula is a much more useful way to calculate plant health using RGB imagery.
Measuring Plant Health is Just One Piece of the Puzzle
“It is extremely important to put your boots on the ground — every NDVI map should still be ground-truthed.” — Norm Lamothe, Deveron UAS Corp
Remember that no matter which algorithm you choose to measure plant health, you should follow up with inspection. Measuring plant health allows you to see variability, but it won’t tell you why that variability exists. You should always get out in the field to ground-truth any crop variance you discover. This, combined with historical knowledge of the field, will allow you to determine the best course of action moving forward.
“The power right now is in understanding your own field. Truly understanding it. Soil type, history — all of it.” — Chad Colby, Colby AgTech
Learn More About NDVI and VARI
Curious to hear what professional growers and agronomists think about NDVI imagery? Read our two part (Part 1, Part 2) blog series which discusses the value of NDVI data in agriculture, complete with advice from some of the top experts in agriculture. You can also learn more about putting plant health algorithms to work on the farm in this post.
Read through some of our support documentation to learn more about plant health and better understand how to use the DroneDeploy platform to fly, process, and analyze your crops this season.