Shaders and Texturing - An Introduction to Computer Graphics for Artists - page 202

Fig. 11.23 The image on the left has been applied as a displacement map to a plane on the right
Fig. 11.24 Two normal maps for “Hexabot” robot shown in Figs. 11.25 and 11.26 (Texture maps
courtesy of Simon van den Broek)
Normal maps do not create new geometry as displacement maps do, but change
the way light affects existing geometry. This means that, just like bump maps, an
object with normal maps will have exactly the same silhouette it has without the