Select Visible or Select by View for surfaces

I have a many faceted mesh object that I’ve converted to many surfaces via exploding a polysurface. The object is a cup. Is there an easy way to select all of the surfaces that make up the outside of the cup? It would be a start if I could select the surfaces I see in a shaded front view for example. Basically I’m trying to “undo” a shell process to recreate the initial solid object.

I’m not sure what you have in your file at this point - meshes or surfaces?
At any rate, you could see if the SelVisible command helps you on your way.

The clients object started life as an stl, was imported as a mesh, was converted to a polysurface, which was in turn exploded into a couple of hundred surfaces. A bunch of those make up the outside of the cup and a bunch make up the inside.
I’ve tried to duplicate the errors starting from scratch.
The attached screenshot shows (left to right):

  • a mesh cylinder (8 around 4 high)
  • converted to a poly surface that was shelled.
  • then exploded to produce 88 separate surfaces.
  • SelVisible was used in the front view on those 88 surfaces and deleted.
    The result is on the right end. You can see the some of the surfaces (but not all) of the bottom (both inside the cup and outside) were deleted. You can see that some of the surfaces on the back side weren’t deleted but are clearly behind the front surfaces.

So for this example, I couldn’t use SelVisible to pick only the outside of the cup. Maybe it’s a tolerance issue. The big problem is that I can’t see why it is, or isn’t, consistent. In this case I would have expected to delete only the front facing surfaces on the outside of the cup. The back should have been intact. The actual case is worse since the artist’s cup has multiple angles on the outside surfaces which only makes the selection even more unpredictable.


Hi Steve – the simplest is, I think, when the thing is still a mesh, use ExtractConnectedMeshFaces at the appropriate angle (<90 I guess) to split the mesh up before converting to a polysurface.


That worked well for this case. I’ll keep my fingers crossed that it works on more complex models. In this case the artist used some basic 3d modelling package so it was quite simple. I often have to try to work with meshes that are created with a 3D scanner. The list of problems with that start point (e.g. noisy, naked edges, spurious data, duplicate faces, etc) is seemingly endless!