Material Editor > Standard material > Maps rollout > Bump button
You can select a bitmap file or procedural map to use for bump mapping. Bump mapping makes an object appear to have a bumpy or irregular surface. When you render an object with a bump-mapped material, lighter (whiter) areas of the map appear to be raised, and darker (blacker) areas appear to be low.
Note: The effect of a bump map is not previewed in viewports. You must render the scene to see the bump effect.
Bump mapping uses the intensity of the map to affect the surface of the material. In this case, the intensity affects the apparent bumpiness of the surface: white areas protrude, and black areas recede.
Use bump maps when you want to take the smoothness off a surface, or to create an embossed look. Keep in mind, however, that the depth effect of a bump map is limited. If you want extreme depth in a surface, you should use modeling techniques instead. For example, the Displace modifier pushes surfaces or faces in and out based on the intensity of a bitmap image. (Displacement mapping is another way to do emboss a surface.)
Grayscale images can make effective bump maps. Maps that shade between white and black generally work better than maps with hard edges between the white and black areas.
The bump map Amount adjusts the degree of bumpiness. Higher values render as higher relief; low values render as low relief.
The bumps are a simulation created by perturbing face normals before the object is rendered. Because of this, bumps don't appear on the silhouette of bump-mapped objects.
Tip: If you render a bump-mapped material and notice aliasing in the highlights, try turning on supersampling and rendering again.
Note: Most controls on the Output rollout don't affect bump mapping. Only the Invert toggle is considered; it reverses the direction of the bumps.
To assign a bump map:
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Click the Map button labeled Bump.
The Material/Map Browser is displayed.
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Choose from the list of map types, and then click OK.
The Material Editor is now at the map level, and displays controls for the map parameters.
(If you choose Bitmap as the map type, you first see a file dialog that lets you choose the image file.)
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Use the map controls to set up the map.
Tip: To avoid aliasing caused by a 2D bump map, go to the bump map's Coordinates rollout. Set Blur to be in the range 0.3 to 0.6, and increase Blur Offset to be greater than 0.0. The default Blur and Blur Offset values work well for mapping other material components, but for bump mapping, lower Blur and higher Blur Offset values give better results.
To remove a bump map from a material:
Tip: You can disable the map without removing it. Simply turn off the toggle immediately to the left of the map button on the Special Effects rollout.
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If the Material Editor is displaying the map controls, click the Type button to display the Material/Map Browser. If the map controls aren't visible, click the Bump map button to display them, and then click the Type button.
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In the Browser, choose NONE as the map type, and then click OK.