Can PIX4D generate Leaf Area Index?
LAI can not be directly calculated in PIX4Dfields, usually you need to measure the light transmission through the canopy to calculate it meaning you need an above canopy and below canopy measurement as it defined as the one-sided green leaf area per unit ground surface area. In other words, it’s a ratio that describes the total “leafiness” of a particular area. This is usually done with devices such as the LAI-2200C Plant Canopy Analyzer.
However there is strong relationship between the LAI and multispectral vegetation indices like the NDVI which is calculated using the near-infrared and red bands of multispectral imagery. NDVI values range from -1 to 1, with higher values indicating more dense vegetation. While NDVI is not a direct measure of LAI, it is often strongly correlated with LAI, and so NDVI values can be used to estimate LAI values.
The best would probably to relate ground-truth LAI measurements with drone data, to calibrate it for the crop of interest, meaning doing a regression of LAI vs NDVI for example.