Normal bump mapping is a way of adding high-resolution detail to low-polygon objects. It is especially useful for real-time display devices such as game engines, and it can also be used in rendered scenes and animations.
A normals map is a three-color map, unlike the grayscale maps used for regular bump mapping (see Bump Map). The red channel encodes the left-right axis of normal orientation, the green channel encodes the up-down axis of normal orientation, and the blue channel encodes vertical depth.
3ds Max provides a number of different ways to create and use normal bump mapping, but the most straightforward and simplest workflow involves these steps:
The low-resolution model should have the general shape and outlines of the high-resolution model, and typically it should be a bit smaller, so that projected detail in the high-res model will appear to be above its surface.
3ds Max applies a Projection modifier to the low-res object.
3ds Max renders the Normals map, which stores normals data from the high-res object. As for other kinds of texture baking, it creates a Shell material and applies that to the low-res object, with the Normals map assigned as the bump component.
Components of Normal Bump Mapping
In the 3ds Max interface, controls for normal bump maps appear in three locations:
Specifically, normal projection controls are found on the Objects To Bake rollout and the Output rollout.
You can apply a Projection modifier yourself, or let Render To Texture do so automatically.
Render To Texture creates this automatically if you turn on Output Into Normal Bump (step 9, above).
If your display driver uses DirectX 8, you can view normal maps in viewports by using the Metal Bump shader. If your graphics driver is DirectX 9, you can view normal maps in any shaded viewport. See Direct3D Driver Setup Dialog.
If your display driver is Software or OpenGL, you can't view normal maps in viewports. However, you can still render them and use normal mapping in renderings.
Normal Projection with Sub-Object Selections
You can associate different sub-object selections with different high-resolution geometry. See Reference Geometry Rollout (Projection Modifier).