Fig. 3
From: New approach to calculating tree height at the regional scale
a Forest canopy shape as an ellipsoid. b A single sphere viewed at position v and illuminated at position i (Li and Strahler 1992). θi and θv are the revised solar zenith angle and view zenith angle, respectively. ∅i and ∅v are the solar azimuth and view azimuth, respectively. ∅i − ∅v is the azimuthal difference between the illumination and viewing directions. τi and τv are the sunlit shadow and viewed shadow, respectively. The shaded area is the mutual shadowing area of the sunlit shadow and viewed shadow