In UDK there is a merge terrain tool in the terrain editor. There are two conditions to be met in order to make it work: terrains edges and their height must be lined up. If everything is done correct, then a line will appear between two terrains, then you use a defined shortcut and that is all. If lets say you are sculpting a terrain and everything looks fine but after some time you decide that more terrain has to be added, then later on painting this (whole but divided into pieces) terrain will be a pain in the arse. You said that this is possible to do by hand. How can I do that? Sooner or later people will start talking about this option.
