I have an object that is cubical in form, but the top surface is roughened. The point density on all sides of the cube (including top roughened surface and flat bottom) is pretty high. For illustrative purposes, it's similar to the following image:

enter image description here

Is there an efficient way to remove all points under the top surface (shown highlighted in orange)? This includes all 4 sides, the bottom, and any interior points. I've read about Blender's Circle Select, Lasso select, etc., but wasn't sure if these were effective options for high-density meshes.

  • $\begingroup$ Have you tried the tools indicated in your question ? What do you mean by high density mesh ? $\endgroup$ – lemon Jul 12 '16 at 17:17
  • $\begingroup$ I'm trying them now, but I thought I'd ask in the meantime in case there's a suggestion I hadn't thought of, or read of. By "high density mesh", i mean ~9.1M faces. $\endgroup$ – AaronJPung Jul 12 '16 at 17:18
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    $\begingroup$ OK, selection will work (lasso or circle or border). You can also (if possible) select an edge loop or a median section and delete it. After that the lower part is easy to remove (select a vertex and ctrl + L) $\endgroup$ – lemon Jul 12 '16 at 17:21
  • $\begingroup$ Box Select (B) could be very useful in this case. Make sure to enter front (or side) ortho view and toggle Wireframe shading before proceeding. $\endgroup$ – Mr Zak Jul 12 '16 at 18:47
  • $\begingroup$ Just set your view to Orthogonal (numpad 5), go to front or right view (numpad 1 or numpad 3), set the view to wireframe (or disable limit selection to visible when in Solid view). Press B to enable box select and drag while left clicking to select the area youi need to delete and press X (or the delete key). $\endgroup$ – cegaton Jul 12 '16 at 22:28

You can select a face from each side of the box then press ctrl-shift-alt-F, this will select all linked flat faces, then you can delete them

  • $\begingroup$ Ultimately, the sidewalls were removed before another, more simple file was given to me to work with. However, this is the solution that would've suited my problem the best. $\endgroup$ – AaronJPung Jul 13 '16 at 16:00

Blender has a built in tool for this called "Select side of Active". To use it you have to switch to vertex select mode and select exactly one vertex. This vertex marks the boundary, that means that either all vertices e.g. to its left or right will be selected after you run the command. See my screenshot for the result, the white vertex was the active one before i ran "Side of Active".

Using the last operator panel (Shortcut F6) you can tell blender which axis and which direction to look for vertices to select. Once done, simply delete them.Vertex Mode - Select Menu - side of active

  • $\begingroup$ I tried this method, but couldn't get it to work properly. Probably something I did on my end :/ $\endgroup$ – AaronJPung Jul 13 '16 at 16:01
  • $\begingroup$ what happened when you tried? You have been in Vertex Select mode for sure? $\endgroup$ – aliasguru Jul 13 '16 at 17:59
  • $\begingroup$ I was in the same modes that you suggested (vertex mode, edit mode, etc.). when I hit F6, I did not get the last operator panel, to choose my axis. $\endgroup$ – AaronJPung Jul 13 '16 at 18:04
  • $\begingroup$ you'll need to do it right after running the select side of active command. if you do something after that, even just selecting something, it will be gone. you can also find the same panel on the left hand side in the viewport. $\endgroup$ – aliasguru Jul 13 '16 at 18:15

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