Modified: 1-27-2021 Hello, we are updating some information according to your questions.
Besides the generation of standard vegetation indices, the use of the index calculator allows us to generate a custom index that adapts better to their specific crop scouting or crop protection needs.
Some of you asked about soil masking; vegetation masking or generating maps within a certain threshold. Currently, the following workaround can be used:
- Process your images and get the orthomosaic
- Generate a vegetation index
- Using the histogram equalization of the advanced visualization tool identifies the values that are from your interest.
- Go to the Index Generator tool
- Click on “Create Custom Index”
- Enter the formula of your index
As an example, we have generated an NDVI index, and we are assuming that plants have an NDVI value of more than 0.4. Therefore, we have used formulas that use a division by zero to cause transparency on pixels with lower and higher values than 0.4 and mask soil or vegetation respectively.
You can adapt this idea using other bands and values.
Soil masked map
Formula:
(nir-red)/(nir+red) + 0/max(0; (nir-red)/(nir+red) - 0.4)
Note: In this formula, using max() will mask everything lower than 0.4. This value 0.4 can be modified depending on your applications
Vegetation masked map
Formula:
(nir-red)/(nir+red) + 0/min(0; (nir-red)/(nir+red) - 0.4)
Note: In this formula, using min() will mask everything higher than 0.4. This value 0.4 can be modified depending on your applications
Vegetation map within a specific range
Formula:
(nir-red)/(nir+red) + 0/max(0; (nir-red)/(nir+red) - 0.4) + 0/min(0; (nir-red)/(nir+red) - 0.6)
Note: In this formula, using max() will mask everything lower than 0.4, and using min() will mask everything higher than 0.6