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In the upper left image, lattice noise alters the magnitude of the teapotís surface normals, which creates a rough-looking surface. Lattice noise at a lower frequency changes the magnitude of the surface normals of the upper right teapot. It appears dented. The lower left teapot is the result of using sin(y)/ 2 + .5 to scale the normals magnitude, which results in a rippled effect. In all cases the profile of the teapot is still smooth. Bump mapping does not change the underlying geometry of the model, but fools the shading algorithm to produce an interesting surface.