Hi Andy, yes that method will generate lines, not faces. I guess Alibre does not try to load curves from .3dm files.

CAD programs are not designed to operate on models diced up into tens of thousands of little triangles. CAD programs expect larger smooth surfaces.

So it's difficult to do what you're trying to do. The type of data you have obtained from the scanning is meant to be loaded into a polygon mesh editing program, not a CAD program.

The process of fitting smooth CAD surfaces to dense triangle data is called "Reverse engineering". Some info here:
https://wiki.mcneel.com/rhino/reverseengineering

- Michael