Photoshop 3D tutorial showing you how to work with Bump maps, Normal maps, and Depth maps.
Bump maps are grayscale images that allow you to fake detail in 3D objects. The detail that they generate is simply a lighting trick on the surface of 3D objects. The actual 3D geometry is not changed in any way.
Normal Maps are very similar to bump maps. They also allow you to fake the illusion of depth and detail on a 3D object without actually adding any 3D geometry. But Normal maps do it in a different way.
A normal map uses RGB information that corresponds to the X, Y and Z axis in 3D space. The RGB channels tell Photoshop the direction of the surface normals are oriented in for each and every polygon.
Depth maps are 2D images that use their luminance values to create 3D objects. Unlike Bump maps or Normal maps, Depth maps in Photoshop do alter the 3D geometry of an object.