Modeling 3D Canopy's Four Components and Gap Fraction at the Sub-Leaf Level Using Ray-Tracing Method

摘要

In this article, a model of architecture (the Clumped Architecture Model of Plants: CLAMP) (Rochdi et al., 2002), which explicitly describes the leaf aggregation and stands dispersion in a generic way and requires relatively small number of canopy's key biophysical parameters as model inputs, was used to generate the realistic 3D vegetation scene. Then a deterministic ray-tracing procedure is used to model four components at the level (i.e., illuminated leaves, illuminated ground, shadowed leaves, and shadowed ground). The component shadowing type is determined by comparing a ray's intersection with leaves or ground between illuminating and viewing directions, then a two-dimensional shadowing pattern for the scene is created. The model was used to identify the main structural parameters controlling the shadowing patterns and gap fraction and study the influence of canopy's distribution pattern both at stand and leaf level on the state of radiation transfer in the canopy.