Bump Maps or Normal Maps on 3D Cylinder

Hi
Bump maps and normal maps simulate surface detail. The actual mesh does not change, but some shadows and highlights are introduced at the rendering stage. This works well to introduce the look of texture to a surface , e.g. wood grain or even bricks and mortar but does have limitations. The surface detail is only simulated and that tends to show on the edges of the model which remain as straight as they were before the maps were used and do not follow the new "texture".

For the actual surface to change then the mesh itself needs to be displaced either by modelling or using a displacement map. Photoshop is very limited in mesh control - you would need to use a 3D application to do it properly. Real displacement, to introduce detail, also  involves introducing more vertices and can therefore eat up memory and slow down rendering. So it is a balance between putting larger displacements on the mesh and finer detail on bump maps/normals.

You can create bump maps and normal maps in Photoshop by starting with a 50% grey fill. Anything blacker than that will be shaded as a hollow anything lighter will be shaded as a raised surface. Then use Filter >3D generate bump or generate normal.

Dave