Smooth Shading vs. Faceted Shading

Spring 1999

University of Maryland, Baltimore County

- 1 color per polygon
- produces "unsmooth" objects
- direct rendering of the geometry
- fast

- assumes object is really a curved surface, approximated by a collection of polygons.
- more realistic rendering
- slower
- Two Types:
**Gouraud**and**Phong**

- Calculate Average vertex normal
- Perform illumination calculation to get vertex colors
- Interpolate vertex colors accross the face.
- Suffers from
*Mach banding :*

Whenever the slope of the light intensity curve changes abruptly,

the surface appears brighter (inflection is concave) or darker (convex) - May miss highlights within a face.

- Calculate Average vertex normal
- Interpolate vertex normals accross the face.
- Perform illumination calculation at each pixel
- More accurate highlights
- Fewer Mach Band effects
- Why do they occur?

Facted Shading | Phong Smooth Shading | Phong Smooth Shading with Volumetric Steam |
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