TrueNDVI vs. Synthetic NDVI Explained

Not all NDVI is created equal.

Normalized difference vegetation index (NDVI) imagery products have become increasingly common in precision agriculture applications. More companies are offering NDVI-like products, including “Synthetic NDVI” images from drone platforms. At Nolde and Associates, it is our mission to provide you only the most valuable plant health data, which is why all of our drone sensors produce TrueNDVI output. It’s important to understand how these instruments are different before deciding which technology makes sense for your site.

What is NDVI?

Agronomists, plant experts, and research scientists have used NDVI for the last 40 years to assess the health of plants. An NDVI sensor uses wavelengths of light outside of what regular RGB (Red, Green, Blue color) cameras can detect. These wavelengths are slightly longer than those of visible light and are located in the near-infrared (NIR) band. Light reflected in the NIR band correlates to the biological processes in plant material. The combination of the non-visual NIR band and the visible red band results in an NDVI value. This value provides growers with an accurate measurement of plant vigor and allows them to zero in on problem areas that need addressing.

So what is the difference between TrueNDVI and Sythetic NDVI?

NDVI is based on the combination of red light and near-infrared light. A sensor that cannot develop a separate measurement of near-infrared light cannot produce NDVI.

An imaging product described as “False NDVI” or “Synthetic NDVI” is exactly that — not NDVI. These products are usually formed by acquiring normal RGB images and manipulating them in a way that hopes to approximate True NDVI. But if the sensor hardware can’t measure and separate near-infrared and red light, the result can never be more than a weak approximation. To attempt to generate NDVI from a standard RGB drone camera is like trying to figure out the color of somebody’s shirt from a black and white photo — the information just isn’t there.

NDVI was created because it provides a great measure of vegetative vigor and because it’s a better measurement of plant vigor than reflectance using any combination of RGB..

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