OH this is a painful process. Annoying and slow as hell.
Literally had to export everything out of UDK as an OBJ file,
Import it into MAYA.
Then export it from MAYA as an FBX file and import it into the new platform.
And I havent even touched the entire game design yet, that was just the terrain and the trees.
Since they are scaled properly in UDK it’s best to export them via UDK and go through that process.
**** if I was proficient in coding. I would make a PLUGIN for the UDK3 for the quick conversion export as FBX w/textures instead of the OBJ files.