ylfink@water.waterloo.edu (ylfink) (01/27/88)
DEPARTMENT OF COMPUTER SCIENCE
UNIVERSITY OF WATERLOO
SEMINAR ACTIVITIES
MASTER'S PRESENTATION
- Thursday, January 28, 1988
Mr. Tim Bennison, a graduate student of this
department, will speak on ``Fast Phong Shading''.
TIME: 1:00 PM
ROOM: MC 6082
ABSTRACT
Phong shading is used in computer graphics to produce
more realistic images than can be achieved using
simpler methods such as flat shading or Gouraud
shading. When Phong shading is used in conjunction with
Phong's lighting model, specular effects (highlights)
are produced and ``Mach banding'' effects are reduced.
Conventional Phong shading interpolates the surface
normal across scan lines, and applies the lighting
model to the normal at each pixel; this method has
traditionally been regarded as too slow for real-time
image generation systems.
Fast Phong shading is a rendering technique that
approximates normal interpolation and the Phong
lighting model with Taylor series expansions which can
be evaluated incrementally in the scan conversion
process. The method results in a significant increase
in the speed of the shading operation; a hardware
implementation of the technique could potentially be
configured for real-time Phong shading. The loss of
accuracy inherent in the approximation techniques can
be controlled and is offset by the fact that the method
can be extended to handle more complex lighting models.
This presentation will begin with a review of the
``classical'' methods of Gouraud and Phong shading. The
details of the implementation of fast Phong shading
will then be presented, followed by a brief look at the
shortcomings of the method. Finally, the issues
involved in extending the technique to the shading of
B-spline patches will be discussed.