hi,
You could use a masking index as mentioned in this post: Soil and plant masking w/ Pix4Dfields
You should use the first option:
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
