Are you building a 20x20 or 10x10 sector terrain? For the SEA arenas 20x20 is still used for historical venues, the MA is now down to 10x10 becasue of our numbers. A 512 map is for a 20x20 and a 256 is for a 10x10. That is a port hole effect for viewing your terrain and giving you the boarders long hand for 20x20, 10x10 and so forth. The center 2048x2048 of the 4096x4096 project space is a 10x10 terrain.