Storing other shading parameters in maps

Displacement mapping

In displacement mapping, the surface is actually modified, in contrast to bump mapping where only the surface normal is modified. This means that displacement mapped surfaces will show the effect even at the silhouette.

A Pixar Renderman image with displacement mapping. Notice that the surface not only appears non-smooth but the silhouette is also non-smooth.

In contast, displacement mapping alters an object’s geometry (Cook, 1984). Compare the profiles and the shadows cast by these two objects. Which is bump mapped?