Adding details or features (variations in color or texture) to surfaces.
Pattern Mapping Technique -- Modulate the surface color calculated by the reflection model according to a pattern defined by a texture function. (This could be a digitized image or a procedurally-defined pattern.)
2-D Texture function: T (u,v)
Inverse Pixel Mapping (Screen Scanning):
For each pixel on screen ( xs , ys )
-Compute the point (x,y,z) on closest surface that projects to the pixel and determine its color from a reflection model (e.g., raytracing).
-Calculate the (u,v) that corresponds to (x,y,z) (inverse mapping).
-Modulate the color of ( xs
, ys ) according to the value of the texture function
T(u,v) at point (u,v).