Sculpting Workflow for Targeted CNC Milling on an Irregular Surface

Hi there,

I’m pursuing an experimental workflow where I want to CNC carve isolated areas of digital sculpting back into the original object that generated the mesh I’m sculpting on.

There are a lot of workflows out there for manipulating a scan, and then CNCing that into a blank workpiece. But since my workpiece is an existing irregular surface, I need to be able to separate the original scan from the deformations I produce

This is where I’m stuck:

I want ALL of my deformations, and ONLY the deformed areas (NOT the original topology of the mesh) to belong to a separate layer so I can export it as a separate mesh, and I do not want to manually select regions. I want it to be automatic or part of the sculpting process. This way I can easily generate toolpaths for it.

I’ve tried to do a boolean difference command in Rhino and it crashed the application. I’m working with a mesh that is 2 million points. Perhaps there is something I’m missing here? Does ZBrush or Rhino have any tools that would help this process? Any tips/recommends highly appreciated, thank you.

As the workflow you describe is 100% mesh based you will be better off using a specialized mesh software, like Zbrush.

One would need more detail to properly understand what you want to do – but in Zbrush one can use several methods to distinguish input mesh and output. There’s sculpt layers which can get turned off and on, you may use morph targets as well as polygroups (selectable groups of faces within a contiguous / closed mesh).
Further you may perform Boolean operations on high res geometry and the modified regions again turn to polygon groups, which give you selectable areas. If you search for the keywords in italic + zbrush you should find plenty more information.