Specular Refelection

• Lambertian term models matte surface but not shiney ones
• Shiney surfaces shine because because amount reflected depends on viewer's position
• Phong Bui-Tuong developed an empirical model:

  

  \

• This is the Phong lighting model
• p is the Phong exponent and controls size of highlight

  Brightest when .

  Small p gives wide highlight, Large p gives narrow highlight

  \

• Our light equation becomes

  

  where

  

  (note that cancels)