The Adding method has been used to calculate vegetation canopy bidirectional reflectance. Appropriate reflection and transmission matrices for canopy and underlying soil layers are developed in terms of canopy geometry and basic optical properties. The model is illustrated by comparisons with field reflectance measurements for blue grama (Bouteloua gracilis) and soybeans (Calahan 9250). Calculations using the Suits model are also included for comparison.
K. Cooper, J. A. Smith, and D. Pitts, "Reflectance of a vegetation canopy using the Adding method," Appl. Opt. 21, 4112-4118 (1982)