Is there a reason that you have set your texture and polygon limit so low? Is this for a mobile game? I like the idea and I'd love to see you carry on further with it :)
I've seen 21 million polygons running at 40fps in Max 2011 on a dual core with 2Gb of RAM and a 9800GT, all depends on how well broken down the scene is.
-also could be used to redistribute polygon density to areas of the face that need more detail vs the back/top of the head... so 3 things... the list may grow.
Hi, Im using the same tutorial, and I got the same problem. Wasnt the whole deal with the mesh polygon number (4096 * 4096) because of requirements from UDK?
The Marmoset Toolbag is a easy to use model viewer. You will need to make your alpha plane polygons back to back in order to get proper lighting on them in Marmoset.
You can scale down those polygons on the uvmap so they don't take that much space. You won't see them anyways, so its not a problem if they are lowres.
Just wanted to add that you don't need such amount of geometry towards the poles, try to keep the polygon size kind of consistant by reducing their number. That will also help for unwrapping.
Oh also check if the UV is flipped for the missing section. In the Unwrap edit window, go to the Select menu and choose Select Inverted Polygons. Flipped UVs won't bake.