Figure 3.

(A) Feature points in spectral standardization. P_b is the minimum point in the region of 470–520 nm; P_g is the maximum point in the region of 520–600 nm; P_r is the minimum point in the region of 600–720 nm; P_nir is the turning point in the region of 740–800 nm, where the first derivative is equal to 0. (B) Spectral slopes S₁, S₂, S₃, and distances D₁, D₂ as variables potentially related to foliar biochemical contents. P_b′, P_g′, P_r′, and P_nir′ are the points on the scaled reflectance curve corresponding to the points P_b, P_g, P_r, and P_nir on the original reflectance curve.