automatic faces selection

Hello everybody,

I am looking for a method to automatically select some faces out of a mesh.

Here is the problem: I imported in blender some CAD files describing some robot parts.
I need to select only the external surface and to separate it from the rest (I am not interested in internal part details). I am doing it selecting face-by-face but it takes very long, so every advice will be appreciated :slight_smile:

Thank you very much!

You could try to move your mouse over one of your needed faces and press L-Key.
That would select all faces that are connected to that one you aimed.

If that doesnt help that much you could try circle select BB-Key (press double) to select your faces.

When in edit mode, there is a button on the right side below your 3D view displaying a cube, the “Occlude background Geometry” button. It makes it easy to select only the faces that directed towards your view.

If you haven’t tried it yet: Blender comes with a wide range of selection options (i.e. loop select, loop→region).

Some are described here:

Others here:

Good luck. If you describe your mesh in more detail we could perhaps help you some more.

Thank you, both of you :slight_smile:
I used L to select connected faces and it worked great.
I also tried loop select but couldn’t make it work the way I wanted…but I needmore practice :wink:

BTW, the mesh is composed by triangles, and I obtain it importing a wavefront .obj file.

The one I am experimenting comes from the forearm of a humanoid robot, and it represents the bottom half of it. Grossly speaking, it is shaped like an half pipe.
Since the object has a thickness, it is composed mainly by two layers, an external and an internal one, connected by small faces on the borders. In other words it is a closed non-convex polyhedron.

Can I add a more significant description?

Oh, triangles. In Blender you work with quads most of the time. As far as I know it’s not possible to loop-select with triangles.

You could try to convert your triangles to quads:

  • With all (or some) faces selected in edit mode: Mesh>Faces>Convert Triangles to Quads (or just Alt+J).

Feel free to describe you mesh in more detail if you need more help. Some uploaded screen shots or a .blend file would make it easier to see the problem more clearly.