Modeling and CSG
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
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.
2D textures can betray 2D nature in images
Hard to texture map onto curved surfaces
Idea: Use a 3D texture instead
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)
CS488/688: Introduction to Interactive Computer Graphics
University of Waterloo
Computer Graphics Lab