05_16_13

Working with mirror geometry in UDK can be a little tricky, so I put together a mini tutorial on how to do it. Most problems that artist experience in UDK with mirror geometry steams from bad UV layouts or light maps (a second UV layout).  Below is the process that I use to mirror my model in Maya and send it to UDK.  I'm using Maya 2013 and the latest build of UDK.

You should have half you model done and UVed (all UVs should be blue at this point)

Select model in maya's view port and shift right click... mirror polygon (select the axis you want to mirror on and +/- value.  (the UVs will mirror for you).  Do not change any geo or UVs.

Adding a proper Light map UV set... after mirroring your stuff

Right click your model... UV set editor (you should have only one set called map1)
Select it and click copy (this is a good time to rename the second set to lightmap)
Go to your UV texture editor and up top click on the UV set drop down tab
Select your second set / light map... changing the name just makes it more organized.
Select one or more vertices in the UV texture editor
Shift right click and select Layout UVs.

You can generate a second set of UVs in UDK, but don't do it; create it yourself.

For tiles you have to match up the boarder edge with grid in the UV editor for your light map.

Here's a video that explains this...

http://www.youtube.com/watch?v=3eDjhOtiyuo

When you import, use FBX with the following checked for static mesh.

Smoothing groups and smooth mesh.
You can keep everything under the covert NURBS checked too.  Of course your model should have been Triangulated prior to baking and exporting.

When importing make sure to check use explicit normal in UDK (that is found under static mesh/ advanced).