ZBrush Tip: Auto Groups: Create Polygroups from Disconnected Mesh Islands

Auto Groups instantly assigns Polygroups to each disconnected surface “island,” making isolation, masking, retopology, and export more precise and predictable. Use it early and often to turn messy imports or Boolean results into a clean, controllable structure.

• Where to find it: Tool > Polygroups > Auto Groups. Toggle PolyF to visualize Polygroups before/after.
• Prep for best results:
  • Run Geometry > Modify Topology > WeldPoints (adjust Weld Dist) to fuse tiny seams that should be one island.
  • Use Close Holes on scans/CAD imports to prevent unwanted extra islands.
  • After Live Boolean or mesh merges, click Make Boolean Mesh first, then Auto Groups.
• Variants:
  • Auto Groups With UV groups by UV shells—great for texture-centric workflows or UDIM organizations.
  • Group By Normals and Group Front can complement Auto Groups when surfaces are continuous but need logical separation.
• Fast selection and isolation:
  • Ctrl+Shift click a Polygroup to show only that island. Ctrl+Shift+drag outside canvas to invert visibility.
  • Split > Group Split creates SubTools from each Polygroup for heavy scenes or baking prep.
  • Mask By Polygroups (Brush > Auto Masking) or Transform > Mask By Polygroup for precise masking and surface protection.
• Retopo and hard-surface handoff:
  • In ZRemesher, enable Keep Groups to preserve panel borders; add Crease PG or Group Loops for crisp edges.
  • Use Polish by Feature post-ZRemesher to refine planes while keeping group borders intact.
• Practical use cases:
  • Live Boolean cleanup: Auto Groups separates results into panels for quick isolation and thickness operations.
  • Scan/CAD prep: Convert noisy multipart meshes into logical islands before Decimation, ZRemesher, or export.
  • Kitbashing: IMM/inserted parts become distinct groups for rapid selection, deformation, and material assignment.
• Troubleshooting:
  • If you get too many tiny islands, increase Weld tolerance or perform a light Dynamesh pass to unify, then Auto Groups again.
  • Ensure symmetry: run Mirror And Weld after Auto Groups so left/right panels share identical Polygroups.
  • Use Visibility > Grow/Shrink to fine-tune shown areas when group borders are dense.
• Pipeline tips:
  • Before baking, Split by Groups to isolate high/low pairs per part.
  • For painting, Polypaint > Fill Object per group for rapid base color blocking.
  • When exporting FBX/OBJ, preserved Polygroups accelerate material ID and selection sets downstream.

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