Bump mapping is similar to texture mapping, but instead of projecting textures onto the surface of polygons or three-dimensional bodies, bump mapping projects surface textures. This makes flat polygons appear uneven, raised and relief-like.
The bumpmapped surface has a three-dimensional texture with heights and depths achieved by gradations in brightness.
The bumpmapping structures are stored as textures and projected onto flat surfaces or even 3D bodies, as in texture mapping. The shadow casts are created with lighting models, they are included in the textures and cannot be changed after bumpmapping by lighting the graphic model.
The technique of bumpmapping is mainly used in computer games because it is not as computationally intensive as ray tracing and because it can be used to achieve a high realism effect.