Bump/normal map

How do you make a different bump/normal map for materials? I read a tutorial on it but it didn’t make much sense to me.

Example: I have a stony texture, I want to use a greyscale image of some cracks as a bump/normal map.

Please tell me exactly how to do it. I got confused with the one tutorial I saw about it on the Blender site.

Thanks a lot.


well, every material can have several texture channels. those blank bars in the texture buttons are the channels. if you click on one of those and choose ‘add new’ from the pulldown menu you’ll add a new channel. so sy you have a marble texture for color, but you want to use a clouds for bump, but not color. go to texture buttons ( assuming your object has a material ) , give it a marble texture, then, back in material buttons, adjust the color to your liking. you’ll see a button called ‘col’ is depressed by default. that means that the texture is being read as color. you’ll notice some other buttons nearby it.
now go back to texture buttons and click on a blank channel and add a clouds texture. again go to materials buttons, and this time, click on the ‘col’ button, so it’s off. now click on the button that says ‘nor’. this tells blender to read that texture as a bumpmap, but not color. nearby is a slider with which you can adjust the nor value, and if you click the nor button again, the normals map is inverted. click again, and it’s off.
hope that helps.