Texture Mapping

Texture Mapping:

• If we add detail by increasing model complexity, then computation cost increases.
• If detail is surface detail, then we can use texture mapping.
• Idea: scan a photo of the detail and paste it on objects.
  • Associate texture with polygon
  • Map pixel onto polygon and then into texture map
  • Use weighted average of covered texture to compute colour.

  \

• Tile polygon with texture if needed
  • For some textures, tiling introduces unwanted patern
  • See SIGGRAPH 97 for method to extend textures (expensive)
• Greatly improves images!
• Not just ray traced image

Bump Mapping:

• Textures will still appear ``smooth'' (i.e., no shadows)
• Bump mapping is similiar to texture mapping except that we peturb the normal rather than the colour.

  \

• Perturbed normal is used for lighting calculation.
• Convincing - usually fail to notice silhouette is wrong.

Solid Textures:

• 2D textures can betray 2D nature in images
• Hard to texture map onto curved surfaces
• Idea: Use a 3D texture instead
• Usually procedural

  Example:

  if ( (floor(x)+floor(y)+floor(z))%2 == 0 ) then
      return RED;
  else
      return SILVER:
  end

  Gives a ``3D checker board''
• Turbulence can also be simulated (marble)