A Simple Shading Model →

Blinn-Phong Reflectance Model

$$ \begin{aligned} L & =L_a+L_d+L_s \\ & =k_a I_a+k_d\left(I / r^2\right) \max (0, \mathbf{n} \cdot \mathbf{l})+k_s\left(I / r^2\right) \max (0, \mathbf{n} \cdot \mathbf{h})^p \end{aligned} $$

• Ambient

  This is approximate / fake !

  Real → Global Illumination

  

• Diffuse

  Shading independent of view direction

  

• Specular

  Intensity depends on view direction