Unified Sun and Sky Illumination for Shadows under Trees

摘要

Assume the sun, sky and clouds are represented as a raster image on a plane at infinity, and the shadows of a tree canopy are represented as a raster transparency mask on a canopy plane. Then the illumination on the ground is the correlation of these two rasters, which can be rapidly computed by Fast Fourier Transform techniques. (ERA citation 12:046999)