I'm not sure if everyone knows how BF2 mapping works, but i'll try to splain roughly...
BF2 maps are area defined. This means that every BF2 map has a defined total area, lets say 4096x4096x4096 units for the sake of this discussion. The entire world (map) exists in this space. You specifically define the boundaries of which a person cannot enter at the borders of the environment, if the environment does not extend all the way to the 4096 edge of the world. In this defined space you deform the terrain to your desired shape using terrain deforming tools. You make hills, mountains, valleys, rivers, lakes, anything you desire. You set a world water level that defines the water level at which all terrain below that level will be filled with water, very cool. Then you add/import your predefined structures. Anyone that has played BF2 knows that there are buildings, water towers, smoke stacks, bunkers, stairways, and everything else that are identical from map to map. These are all drag and drop, predefined, objects. After you drop an object you can further refine your terrain to accurately and properly conform to your object. This type of mapping system means every map is loaded into the same defined 4096x4096x4096 area. The amount of objects you place in your map, the settable View Distance, and the detail of your terrain determine how complex and laggy your map will be.
I am well aware that anything of this nature is purely fantasy for DP, but it would absolutely rock and make the game so much better in the mapping department.