Creating a surface from polyface meshes

[JDB423]

I have received a file from a landscape architect on a project I am currently working on, the architect have built the external levels model in Revit and it has been set up as a 'building' model which means that every object modelled is essentially a slab with a thickness (depth). This means that when it is exported to a file we can open in Civil 3D, there are multiple polyface meshes on top of each other representing the thickness (see image for example), we only need the top layer of polyface meshes to create a levels surface from.

How would I go about creating a surface from these polyface meshes that only makes use of the ones on the 'top layer'? Would I need to go through and manually delete all of the ones I don't need? Or is there a way it can be refined/converted in Revit before exporting to a DWG for us?

I can't share the CAD file unfortunately.

Any help would be great, thanks.

[neilyj666]

I don't know how these are created in REVIT but I'd get the provider to do all the adjustment work for you

[JDB423]

Yeah it seems that I'd have to manually go through the file and delete all the unwanted meshes, considering it's a large file and there's hundreds, if not thousands of meshes it would be a very time consuming task.

[MSchille-1994]

Depending on the elevations of all your 3D Faces, you can use the Quick Select icon on the Prospector and create a selection set using the Less Than or Grate Than functions in the dialog box.  This would only work decently on fairly flat ground.