Imagery uploaded to DroneDeploy that was captured using a compatible NDVI Sensor will automatically be processed into an NDVI map. You'll see several options to display your data in Ag Toolbox (NDVI + Thresholding).
Ag Toolbox compares input channels of light to quantify plant health in different ways. Use the formula guides below to understand each assessment index's value and visual output.
The traditional formula for NDVI compares Near Infrared and Blue light. It is great for measuring healthy, green vegetation over a wide range of conditions.
Below is an NDVI map calculated with the standard formula. We'll use this to compare to the other formulas in order to present different aspects of your data.
ENDVI includes a comparison of Green light in addition to NIR, Red, and Blue in order to give a more sensitive result. This isolates the indicators of plant health, and can be used to assess the presence and health of a crop.
Notice the darker reds that create more contrast compared to the above NDVI image.
SAVI calibrates for soil reflection by using a standard factor within the calculation of pixel value. This is useful in areas of low vegetation where the soil can be seen through the canopy, because it suppresses the value of soil pixels.
SAVI is great for sparsely vegetated areas.
OSAVI is a variation of SAVI, with a lower calibration factor. Using OSAVI, there is more variation with the soil than with SAVI, but it is also more sensitive to vegetation. In the example below, we see more subtle vegetation differences with OSAVI than with SAVI above. OSAVI would work well in an area with a dense canopy and a wider spectrum of vegetation.
OSAVI is more sensitive to vegetation than SAVI and would work well in denser canopies.
RDVI is similar to SAVI in that it suppresses the effects of soil and sun. Unlike SAVI, however, it does not work as well in sparsely vegetated or dry areas.