so, this is what it looked like when I exported the .obj file:
and when I drag this into MadMapper it looks like this:
and as you can see there are still some strange lines in there, that shouldn't be there. in the lower right is the projector preview, where I can see nothing.
If you want, you can give the .obj file a look here: https://drive.google.com/open?id=0B1MX5 ... W9RQTBqMzQ
I'm sorry if I'm missing something really obvious and I'm very grateful for your help so far.