Terrain height-map import

hi, I'd like to know if its possible to import say, a map, and use it on the terrain to get that map in 3D, is this possible and if so how do I do it? thanks.

Depends on what format the map is in. If it has height information, then yes, you could potentially write a script that converts the map to a heightmap Unity can use, if you have the specs for the format. The only format that directly imports is 8- or 16-bit grayscale raw files.

There's a script to import a heightmap from a texture in your assets folder on the wiki here.