   Terrain - World Building
  From my understanding, terrain tools are usually for the generation of a map of around 2km~4km square. As a result, large amount of such small maps must be joined together to form a large seemless world.My problem here is that, is there any tools out there which do this job of joining maps more smoothly and seemlessly. Or do I need to handle this manually by scripting the heightmap and etc., in order to obtain a large seemless world?Thanks for help.   
  Well which terrain tool are you using? What is the output from it? What type of input to your program do you need?   