All About 3D

Here is a method using the "Dynamic Paint" & "Mask" modifiers to have only the parts of an object that are in the camera view subsurfed and displaced.

Various ways of rendering only the shadow (and indirect lighting) on a surface. Very useful for floors in external scenes.

Using Blender's adaptive tessellation (subsurf) modifier to apply realtime displacement in the object's material output instead of using the "Displacement" modifier.