Editing Bump mapping (section)

===Methods===
There are two primary methods to perform bump mapping. The first uses a [[heightmap|height map]] for simulating the surface displacement yielding the modified normal. This is the method invented by Blinn<ref name="Blinn"/> and is usually what is referred to as bump mapping unless specified. The steps of this method are summarized as follows.

Before a lighting calculation is performed for each visible point (or [[pixel]]) on the object's surface:
# Look up the height in the [[heightmap]] that corresponds to the position on the surface.
# Calculate the surface normal of the heightmap, typically using the [[finite difference]] method.
# Combine the surface normal from step two with the true ("geometric") surface normal so that the combined normal points in a new direction.
# Calculate the interaction of the new "bumpy" surface with lights in the scene using, for example, the [[Phong reflection model]].

The result is a surface that appears to have real depth. The algorithm also ensures that the surface appearance changes as lights in the scene are moved around.

The other method is to specify a [[Normal mapping|normal map]] which contains the modified normal for each point on the surface directly. Since the normal is specified directly instead of derived from a height map this method usually leads to more predictable results. This makes it easier for artists to work with, making it the most common method of bump mapping today.<ref name="Mikkelsen"/>