bump mapping

[Harabecw]

Hello.
I was wondering, how exactly does bump-mapping work?
does it create a pattern or can you tell it to "do a bump here, and another one here"?

EDIT: on a side note, after seeing ATI's Natural Light demo, I have to say: Gawd. YES. one of the most beautiful scenes I've seen. I can't even begin to imagine the great graphics we'll see in 2005+

 

[AdvancedRobotics]

every texture consists of texels that basically have a code that bump mapping reads. Bump mapping determines the hight/depth of each pixel on a texture map and basically determines how much to "bump" it: add texture/emboss it to make the texture look more realistic.

Bump mapping goes not add polygons to the texture map, instead it just reads the texels and determines on a per pixel basis how much to "bump" the texture.