With the introduction of DirectX 9, the technology for depth effects was improved further. Parallax mapping uses a modification of the texture coordinates to simulate uneven surfaces. The objects and surfaces still remain smooth and unchanged, though.
In current games, the effect of parallax mapping can be seen even better. If you look at a surface, the structure is very defined. How far the structure is defined will depend on the lighting situation and the point of view. The lower the angle, the less the depth effect can be seen.
With steep parallax mapping, the depth effect of the structure is more easily recognized when compared to regular parallax mapping. Stalker: Clear Sky has the improved procedure, which again only simulates the structures—with a low point of view angle, the uneven surfaces disappear.
The next generation of technology is displacement mapping. With this technique, the surface is given a proper structure that even generates shadows; the unevenness also changes the geometry of the object. The point of view doesn’t matter, as the depth effect is always visible.