ZBrushCentral

Painted Mask to Cut Hole through Double Sided Skin

ZBrush Usage Questions
#1

Hi All,

Having trouble coming up with a workflow to cut a hole through a double sided skin from one side to the other from a painted mask only on the top surface for instance. Creating a new solid shape minus the mask.

Have tried reversing panel loops but has trouble with the reverse side face.

Any suggestions for best work flow would be greatly appreciated.

Attachments

Double Sided Skin.JPG

#2

The best I can come up with is:

  1. Duplicate your subtool.
  2. On the duplicate, draw your mask.
  3. Press Ctrl+W, or Polygroups>Group Masked Clear Mask.
  4. In order to get a smooth edge, use Geometry>GroupsLoops. Then isolate the masked area and make a single polygroup.
  5. Press Tool>Subtool>Split>Groups Split.
  6. Delete the subtool with the hole. You should now have two subtools - the original (whole) mesh and a shape based on the mask.
  7. Select the shape and use Deformation>Offset to move slightly away from the other mesh.
  8. Store a Morph Target.
  9. Use Deformation>Offset to move the shape to the other side of the original mesh. You’re defining the path of the ‘hole’.
  10. Press Morph Target>Create Difference Mesh.
  11. Delete the shape subtool and append the new MorphDiff_ mesh as a new subtool.
  12. Switch to the original subtool and turn on Dynamesh. You may need to redo to make sure you get the resolution you want.
  13. Switch back to the MorphDiff_ . Click the second icon from the left in the subtool list (for Subtraction) and then press Polygroups>Group As Dynamesh Sub.
  14. Switch back to the original subtool and press SubTool>Merge>Merge Down. The two subtools should be merge and if you turn on polyframes (Shift+F) the MorphDiff_ shape should be white.
  15. Ctrl+drag the background to re-Dynamesh. The shape should be cut from the mesh create a hole.

It’s quite a complicated workflow so back up your stuff first!

The Dynamesh method I’m using is here:
http://docs.pixologic.com/user-guide/3d-modeling/modeling-basics/creating-meshes/dynamesh/with-subtools/

Attachments

Dog-mesh.jpg

#3

Many thanks for that will give it a go - suspected it was a winding road to travel.

#4

It’s possible I’m missing some of the specifics of your particular situation, but there are many ways to do this, as long as you view it as a multi-part process. It will be easier to do if the volume is already a solid closed mass first, so you’d want to close that portion at the bottom before cutting with your masks.

If your object is symmetrical so that you can just mirror the masking from side to side, it’s super easy. If not, consider using the mask lasso to draw your mask shapes, as that will “select through” to the other side. Then just convert the masking to polygroups, smooth as desired, delete the target polygroups on each side, and use the Curve Bridge brush to draw in new bridging geometry.

maskcut1.jpg

Another way to “paint through” to the other side on an asymmetrical object, is to use the “double-sided” option option in Projection Master, and polypaint the mask shapes. Convert the resulting polypaint to masking in the masking menu, and proceed as above.

If the situation is more complicated than the above solution will allow for, you can always make a “cutting object” from your masking, and perfrom a dynamesh Sub. There are half a dozen way to do that. I’ve used mesh extraction below to start the cutting shape, and used Transpose Extrusion to extrude one side of the object out in a constant direction (a subtool extract will project out from the normals on a curved surface, so if you dont make a uniform extrusion, the resulting holes on either side will be different sizes). Then I just performed a Dynamesh Subtraction via subtools. Be sure to read the instruction on how to do that closely, as it’s a bit of a fussy procedure.

maskcut2.jpg

In addition to Marcus’s suggestion, that might give you a few more ideas to consider.

#5

Hi Guys,

Thanks for both recommendations the shape that I have is symmetrical but the internal space is a non uniform wall thickness. Here is cutaway of the model did a rough off first method and the morph target worked as I reduced the target towards the centre and the offset between the two created the shape which I was able to cutout. Will post final model.

Capture.jpg

#6

Final Model Worked a Treat based on method1 - will use method2 for symmetrical items - thanks heaps for the input GUYS!

Now to print and cast it!
Final.jpg

#7

Looks great! So glad you got it working. And please post a pic when you’ve cast it.