Found this on polycount
QuoteUDK uses directional lightmaps, and to compute that directionality UDK has to establish some tangent basis for the surface. The editor does this based on whatever UV's are in channel 0 by default. So, if your doing any kind of texture atlasing or mirroring UV's with normal maps, you can do a little trick. Since your lightmap UV's will always be laid out nice and clean with no overlaps or mirroring, put your lightmap UV's in channel 0 so UDK calculates tangent basis based on those, then your diffuse UV's in channel 1. Then use the coordinate node to set all your UV coordinates to channel 1 in your shaders.
It takes a few extra steps to set up your materials like this but it should fix the issue. Otherwise, stick a mesh in front of it and cover it up [Blocked Image: http://www.polycount.com/forum/images/s…ons/poly120.gif]
Try that ![]()
http://www.polycount.com/forum/showthread.php?t=94079