Introduction

• Want to shade surfaces
• Lighting calculation for a point

  Given: and and surface properties (including surface normal)

  Compute: in direction

• Need surface normals
• Commonly, surface is polygonal
  • True polygonal surface: use polygon normal
  • Sampled polygonal surface: sample position and normal
• Want colour for each pixel representing surface

Flat Shading

: 

• Shade entire polygon one colour
• Perform lighting calcuation at:
  • One polygon vertex
  • Center of polygon

    What normal do we use?

  • All polygon vertices and average colours
• Problem: Surface looks faceted