Bump Mapping

Bump maps use textures to perturb an object’s shading normals to create the illusion of relief on the object’s surface. Because they do not actually change the object’s geometry, they are best suited to creating fine detail that does not come too far off the surface.

The sphere shown here was bump-mapped using the texture shown below. A negative bump factor was used to make the white areas bump outward.

Shaders Used for Bump Mapping

When Not to Use Bump Maps

Because bump maps do not actually alter object geometry, their limitations can become apparent when too much relief is required, as you can see on the sphere shown below.

Even with a very high bump step, the bumping is not convincing at the edges where there is no indication that the surface is raised.

In these cases, it's better to use Displacement Mapping, which actually alters the object's surface and creates visible detail at the object's edges.

See Also

• Displacement Mapping
• Using Bump Maps with Displacement Maps