Hello @makerbae,
I can’t say anything for certain without being more familiar with the model and process in question. However this sounds awfully thin for the Dynamesh feature. I can’t immediately produce any crashes with the Create Shell feature, so I’d guess your issue is related to problematic mesh geometry, or a mesh that is fundamentally unsuitable for the feature you are attempting to use.
Dynamesh requires closed volumes with a minimal degree of thickness to work. Any areas that are read as an open 2D volume, or especially thin and delicate areas will begin to break down and disintegrate under the Dynamesh process. This will create fragmentary geometry that will be problematic for many processes in ZBrush. If the mesh has undergone previous Dynamesh operations it may already be problematic. Be sure to check for geometry that is breaking apart in locations or that may have disconnected fragments of geometry floating above the surface. If you see anything like this it will be necessary to repair those areas or cut them away and resurface them.
Check also for errors with Geometry> Mesh Integrity> Check Mesh. A mesh that reports severe enough issues here is considered problematic and may cause crashes when you attempt to work with it.
The above said, it’s possible the mesh is simply not suitable for either the Dynamesh feature OR the create Shell feature. As the Dynamesh documentation explains, this feature is designed to be useful when you are rapidly developing form and frequently changing the mesh up to about a medium level of detail. It becomes less useful for meshes with fine delicate features or surface detail, and it will be necessary to transition to the traditional subdivision toolset to continue to develop finer detail on those models.
Furthermore, Create Shell does not adjust the form of the interior surface, it merely displaces from the outer surface. What may be happening is that the shell you are trying to create is too thick for any delicate features you have.
In that case, you may need to manually create a shelled mesh with an interior volume that has been simplified to omit those thin areas from it. So you may have better luck with the following:
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Check the mesh for existing issues as I explained above.
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Duplicate the target mesh as a subtool. The duplicate will be your interior surface.
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Use the Geometry> Tessimate feature to simplify the form of the mesh, and “round off” the finer details. As you increase the amount of tessimation, you should see the finer details start to disappear until you are left with a much softer, simpler version of your mesh.
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Use Tool> Deformation> Inflate with a negative value to shrink the mesh in on itself to the desired degree. Your ability to do this will be improved by simplifying the mesh as you did in step #3. Rounding the form of the mesh more and eliminating fine details will give you more leeway to push the mesh in on itself before the surfaces in especially thin areas begin to “push through” each other, which may cause issues with the geometry.
Example: Load the DemoHead Ztl, and Dynamesh it to turn it into a closed volume. You could shell that mesh, but the finest features like the ears will be included in the shelling. However those features are so fine there is no room to create an internal cavity in that location. If you Tessimate and gradually increase polygon size, you will see this form simplified and eventually omit the ear detail altogether. Now you have a much rounder and simpler internal shell with much more room to easily push in on itself without pushing through itself.
- Use Live Boolean, not Dynamesh, to create a new mesh from the two subtools with the interior volume set to subtractive mode. This will create a new combined tool with a cavity with a much simpler and rounded surface that omits the finest surface detail from the original mesh. Decimate to reduce polycount as necessary, and export.
Hope that’s helpful!
