Congratulations to cosmohause, Azurain, and Harleen on being this season's Spring Members of the Season!
No idea what BATIM is, and it's been a while since I've used Unity, but from what I remember, there were a couple OBJ and FBX exporters in the asset store, along with Unity's heightmap exporter.Here's two of them:Scene OBJ ExporterFBX ExporterAs for the terrain, it depends on whether you want it as a mesh or just a heightmap. If I remember correctly, you could export terrain heightmaps from Unity, the only problem was that they were in the .RAW format. I believe RawTherapee can convert them directly into .PNG images.If you want the mesh, then you'll have to plug in a script yourself, but the wiki has instructions on how to do that, take a look here: TerrainObjExporter.