
344 Virtual Reality: Concepts and Technologies
Phenomenological Projective
1D
3D
Models
Implicit
Explicit
Figure 15.3 Composite typology of BRDF models
The first attempt was by Goel (1988) who divided the BRDF models into five groups
depending on whether they are empirical or are based on a precise characterisation
of the materials. As this classification was too general, Roujean (1991) suggested an
extension to the same, which however in an attempt to be extremely precise, was not
logical in terms of division.
In fact, some models can belong to several groups simultaneously. Besides, it is
sometimes difficult to classify them as some groups do not really ...