Point cloud roofs into meshes

Hi all
I’ve got point clouds of vast areas and I’d like to be able to extract terrain, roads, vegetation and roofs separately and bake them into mesh models but the roofs are giving me a headache: classification within the clouds is done so that buildings and parts of vegetation are on same channel so I can’t extract them right away in CloudCompare.
Instead I have imported the semi-cleaned cloud as a .xyz into GH and used terrain database 2d outlines of buildings to crop off points outside building “walls”. I’ve done it by extruding the 2d outlines, made them into brep and used “points in brep”.
Now I’d need to make each group of points (=roof) into separate meshes. This is propably a rather simple question but how to graft the Cull pattern list so that they’d make separate meshes instead of one? huge roof mesh?

And since the new version of GH seems to support .e57 import, could this be done with direct import instead of importing a .xyz and thus making the model really heavy?

Please see the file attached; I’d like to get the points inside the breps to be grouped according to in which brep they’re positioned.
grafting.gh (88.2 KB)