ZBrush Tip: Fast Hard‑Surface Segmentation with Group By Normals

Accelerate hard-surface segmentation with Polygroups created via Group By Normals. It’s a fast, reliable way to define clean regions for masking, creasing, remeshing, and UVs. If you need licensing, add‑ons, or expert advice, connect with NOVEDGE or explore ZBrush options at NOVEDGE: ZBrush.

• Where to find it: Tool > Polygroups > Group By Normals.
• What it does: Clusters polygons into Polygroups based on the angle between their surface normals, producing logical, feature-aligned regions.
• When to use: Before ZRemesher, UV unwrapping, Group Loops/Crease workflows, Live Boolean cleanups, and selective masking or visibility control.

Quick setup

• Enable PolyFrame (Shift+F) so you can immediately see group boundaries.
• Clean the mesh if needed: Tool > Geometry > Mesh Integrity > Check Mesh Integrity (then Fix if required).
• For noisy scans or triangulated imports, lightly apply Deformation > Polish By Features or use Decimation Master to reduce micro-facets.

Essential workflow

1. Optionally isolate only the surfaces you want analyzed (Ctrl+Shift visibility tools) to speed results and avoid stray clusters.
2. Open Tool > Polygroups and set Max Angle:
   • 5–15°: tight, planar splits for crisp panels.
   • 30–45°: balanced segmentation for props and mech parts.
   • 60–90°: broader regions on gently curved forms.
3. Click Group By Normals and review the result in PolyFrame.
4. Adjust Max Angle and repeat until boundaries align with intended features.

Turn groups into production assets

• KeepGroups + ZRemesher: In ZRemesher, enable KeepGroups and Detect Edges to preserve group borders while generating clean quads.
• Group Loops: Tool > Geometry > EdgeLoop > GroupLoops to add support loops along group borders for sharper transitions.
• Crease by Polygroup: Tool > Geometry > Crease > Crease PG, then subdivide for hard edges that hold form.
• UV Master: In ZPlugin > UV Master, enable Use Polygroups to unwrap each group as a UV island—great for clean texture seams.
• Mask/Visibility: Brush > Auto Masking > Mask By Polygroups for brush isolation, and Ctrl+Shift+click a Polygroup to toggle visibility quickly.

Tips and troubleshooting

• Avoid “confetti” groups by slightly increasing Max Angle or lightly polishing features first.
• For symmetrical assets, use Tool > Geometry > Modify Topology > Mirror And Weld before grouping to maintain mirrored IDs.
• Combine with Auto Groups to separate distinct shells, then refine with Group By Normals for feature-based segmentation.
• Limit operation to visible polygons to improve performance on heavy meshes.
• Assign a custom hotkey to Group By Normals for fast iteration (Ctrl+Alt+click the button, then press your key).

Pro tip: After Group By Normals, run a gentle Polish By Features pass and re-group to reduce micro-breaks while retaining design intent. For purchasing, training, and pipeline consultations, NOVEDGE can help you tailor ZBrush to your studio’s needs.