12-04-2014, 12:03 PM
Illumination (Lighting)
Introduction
Realistic displays of a scene
Perspective projections of objects
Applying lighting effects
Illumination model
Lighting model or Shading model
Calculate the intensity of light for a given point on the surface of an object
Surface-Rendering algorithm
Use the intensity of a given point to determine the light intensity for all projected pixel position in a polygon
Light Sources
Types of light source
light source (direct)
light reflector (indirect)
Two light emitter models
Point light source, see (b)
Distributed (Area) light source, see (a)
Types of illumination models
Local Illumination Models
Only considering the interchanges of the light sources
Global Illumination Models
Concerning the interchange of light between all surfaces
Ray-Tracing, Light as a particle
Radiosity, Light as a energy
Ambient Light
Equally on all surfaces from all directions.
Results from multiple reflections of light from the many surfaces in the environment
Our illumination equation becomes
I = IaKa
Ia : intensity of the ambient light( to be constant)
Ka :ambient-reflection coefficient ( 0 ~ 1)
depends on object’s material
be empirical convenience