“The classification of textured surfaces under varying illuminant direction,” Ged McGunnigle, PhD dissertation, Heriot-Watt University, June 1998. The author writes:
“This thesis sets texture analysis in a physical context…. The first component is the rough surface, models of the surface topography are selected from the fields of tribology and scattering….
“We illustrate the importance of illuminant direction for rough surface discrimination with the following example. Consider the fossilised trilobite (Elrathia Kingii, 550 MYA, Utah) shown in Figure 1.1.3a. Here the fossil is illuminated from tau=90° and there is little texture information that can be used to segment the fossil from the surrounding matrix.”