Practical method to model trees for daylighting simulation using hemispherical photography

The ability to simulate the effect of trees on natural light performance in buildings is contingent upon accurate simulation of light passing through the canopy. Accurate simulations require some assumption of leaf angle distribution to compute canopy gap fractions. The ellipsoidal leaf angle distribution can very closely approximate real plant canopies. The method requires calculation of leaf area density from observed distribution of gap fraction as a function of zenith angle. Hemispherical image acquisition and analysis is used to measure gap fractions. Based on the results, the gap fractions of a theoretical tree are predicted. The results will guide to develop a 3D tree model that can be used in lighting analysis software such as Radiance.