rendered image to uv map

i know this title sounds kindof strait forward, but i have found it more complicated than i had thought…

the method i am speaking of, is for creating LOW POLY charaters. what is done, is you create a base mesh (low poly). i would add a multi res, and sculpt it in a higher polly level. when i render it, there will be natural shading on the high poly model, i crate a very simple uv map, meaning if there are wrinkles in the low ploly design, there wil be none, but in the high poly design i will sculpt the wrinkles instead of shading them in the uv map. i will then render it out, it will look more realistic than if i uv map the shading into the wrinkles. but now to convert a high polly uv map into a low ply design. in most 3d software that supports uv mapping, i would be able to take the shading from the rendered image, and it will unwrap the shading as an alpha on top of the uv map, adding the natural shading to the uv map image. now when i go to the low polly design, and there is less detail in the mesh, it will look like a high poly design due to the uv map taking the shading from the rendered high polly… hu haaaa hu haa hu haaaaaaa… that was a mouth full…

sorry for being mr block of text and im sorry if this is hard to reed. if so, let me know wher you dont understand and i can elaborate.

Are you asking something or just telling?

The way to simulate high poly using low poly is to use normal maps. Look for that in youtube to see how wonderful it is.

You create a poly mesh and unwrap it. Make a copy and subdivide and sculpt it. Then you bake the detail of the high poly mesh to the low poly mesh as a normal map. Then you apply to the low poly that normal map and it looks like it is the high poly mesh.

But Cycles has not normal maps yet. Blender internal yes.