Illumination and Shading

Computer Graphics Jargon:

• Illumination - the transport of luminous flux from light sources between points via direct and indirect paths

• Lighting - the process of computing the luminous intensity reflected from a specified 3-D point

• Shading - the process of assigning a colors to a pixels

Illumination Models:

• Empirical - simple formulations that approximate observed phenomenon
  

Java3D : Real Time illumination model : lots of approximations. No Shade, simplified transparency, no reflexion (miror).

• Physically-based - models based on the actual physics of light's interactions with matter

Raytracing, Radiosity...

• Local illumination model / Global illumination model

Light Sources

Ambient, Directional, Point, Spotlights, Area, Extended

Surface Properties

Ideal diffuse reflector : a very rough surface. :

Specular reflector : Shiny surface : Very smooth surface (mirror) : Reflection : a special case of the Snell / Descartes law

Phong Lighting model

Shading or Surface rendering algorithm

Constant or Flat Shading

Vertex Normals

Gouraud Shading : Interpolation of the intensity

Phong Shading : Linear interpolation of the surface normals / Illumination model applied at every point