Phong illumination model is developed by Phong Bui Tuong. According to the model maximum specular reflection happens when b= 0 and falls when b increases.
Rapid fall is approximated by:
n: Specular reflection parameter
Larger values of n are for shiny surfaces and smaller values are for dull surfaces. For perfect reflector n is infinite.
Specular Intensity can be defined as:
b= angle between viewing vector and specular reflection vector R.
|S| = sin a
R = N cos a + N cos a – L
R = 2N cos a – L
cos a = N. L
=> R = 2N (N.L) – L