2.4.2. Canopy Structure Feature Set

Based on the multispectral images of maize lodging and bare land collected by UAV, we constructed two DSMs of the study site. The DSM of bare land, which is not a ffected by maize height, can be considered as the digital elevation model (DEM) of the study area. The DSM of maize lodging was subtracted from the DEM to generate a canopy height model (CHM), which was employed to calculate nine CSFs (Table 3).

**Table 3.** The calculation formula and implication of canopy structure features (CSFs).


Note: H1,2,3 ... n represents the canopy height of each pixel in each square meter area; n is the number of points; hi is the height of points; p represents the percentiles of height; j and g represent the integer part and fractional part, respectively.
