Copying UVs from a high to low poly model? I am working on several projects where each mesh has 3 LOD levels.

Originally I completed the Highest poly model, applied materials, uv mapped each mesh, duplicated the object and then optimized the duplicate. This worked fine and the material and UVs were set the same on all LODs.
Now I have been told that each object should only have one material and UV map. If I was simply to remove the materials the end result would be overlapping UVs, which is not acceptable obviously.

So I now face trying to match up the UVs from all the object LODs.Is there a way to copy the UVs from one object to another that has a different number of poly?
You can try the "transfer data" tool (the modifier also works, sometimes...).  

Here is a "HD" mesh with UV and texture  

  

And here is a LD mesh without UV
  

Select your LD mesh first and then add your HD mesh to the selection with Shift+Right click. The last selected object is considered as active.
Open the tools bar with T. In the Tool tab, scroll to Edit and click on "Data Transfer: DATA" button

Select "UV" in the menu.

Choose the options that looks the best.

The UV has been transferred from the HD mesh to LD mesh.

Now you can create the seams from UV islands from the UV menu in image editor.
  

The LD mesh has Seams, UV and the texture is OK