Normal Map - Displacement

[Freelance3D]

Hi,

i use Zbrush for a while now and have always used sub pixel displacement for rendering low res models with a high freq map.
Have not cared about normal maps because i had no way to use them (i know there is a plugin for max 6 but it´s not very good).

Now with the Normal Map coming with Max 7 i wonder what is the difference?

The examples i saw look equal to what is possible with sub pixel displacement.

I thought it will be less accurate, so that it is for games, but now i hear that it´s used for movie production too.
Normal mapping can displayed in the viewport and that is a great but there must be reasons for sub pixel displacement.
Or will normal mapping replace sub pixel displacement?

Will GI work with normal mapping?

I know the Zbrush threads on CGTalk but don´t saw anything that explains pro and contra of both methods.

Im a bit in the dark... please help me out.

[trixian]

Normal mapping and sub pixel displacement are two completely sepparate things. Displacement alters the geometry, whilst normal mapping only seems to. Think of normal maps as bump maps on steroids.
Now the interesting part is where one uses normal maps in conjunction with displacement. Mental ray has some specialized shaders for that.

[RErender]

The biggest difference, as my coleague pointed out, is in the edges, as when looking passed the corner of a stone column. While displacement actually forms new geometry and an erose edge, the normal mapping is still just a trick off light and shadow, the edges are only as complex as the underlying geometry. Normal maps are leaps and bounds above bump mapping and can be used to great effect but when edge detail matters then displacement is the way to go.