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Bump MappingBump mapping is a technique used to add more realism to images without adding a lot of geometry. Texture mapping adds realism by mapping images to geometric surfaces. Bump mapping adds per-pixel surface relief shading, increasing the apparent complexity of the surface. This uses lighting properties and indicates which parts are dark and which are light on a texture, making it look more geometrically complex because of light refraction.
Surfaces that should have a patterned roughness are good candidates for bump mapping. Examples include strawberries, oranges, stucco, wood, water, etc.
A bump map is an array of values that represent an object's height variations on a small scale. A custom renderer is used to map these height values into changes in the local surface normal. A normal is the perpendicular vector to a plane -- 90 degrees from the plane. These normals are combined with the surface normal, and the results are used to evaluate the lighting equation at each pixel.
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