What is "bump mapping"

n. (context computer graphics English) A technique where a perturbation to the surface normal of the object being rendered is applied to each pixel, based on a texture map, prior to calculating the illumination, so as to produce a richer, more detailed surface representation.

Bump mapping is a technique in computer graphics for simulating bumps and wrinkles on the surface of an object. This is achieved by perturbing the surface normals of the object and using the perturbed normal during lighting calculations. The result is an apparently bumpy surface rather than a smooth surface although the surface of the underlying object is not actually changed. Bump mapping was introduced by James Blinn in 1978.

Normal mapping is the most common variation of bump mapping used.