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Normal Mapping and Displacement


The biggest challenge in 3D CG is to fake actual surface details.
It is a requirement to balance out render time and manageable mesh density.

In the recent years high res mesh sculpting became a very hot topic in CG
is is now being adapted into many other areas such as Product and Jewelry design.

The process is as following.
  1. Model a low polygon model
  2. Subdivide it highly and sculpt your surface structure
  3. Render Bake that wire mesh into an image format
  4. Apply that image to a second low polygon model which is interactively subdivided during rendering.

The reason for that is because the image is applied to a second low polygon model the render result
will be as desired, but without having to deal, work, animate with a high polygon model.

There are two ways to generate those images:

Realtime Displacement Texture
Texture based displacement is using the subsurf subdivision modifier and than a displacement modifier.
The displacement modifier is using the generated texture to actually deform the mesh which
is highly subdivided by the subsurface modifier. This results into a true 3d dimensional surface structure.

Pro: True geometry
Con: High density mesh build up for render time.
Use: On smaller areas.

As you can see the right mesh is the subdivided result of the Base Mesh with the displacement added.

Normal Mapping Texture
Texture based normal mapping is a much more advanced version of bump mapping.
A so called normal map is being generated which stores the light and shadow information.
As you can see it is not a normal gray scale image.

Pro: Ver fast to render, looks quite realistic
Con: No true 3d geometry, edges of objects do not show the displacement
Use: If your model has many fine details you would like to render as structured.