Rhino 3D Tip: Smooth command — relax control points to improve curve and surface fairness

Even, fair control‑point flow is essential for high‑quality Rhino models. The Smooth command quickly relaxes noisy points on curves, surfaces, meshes, and SubD while preserving overall intent. Used in small, controlled passes, it removes ripples before they become fabrication or rendering problems. If you need Rhino licenses, add‑ons, or expert advice, check NOVEDGE.

What Smooth does:

• Moves selected control points or vertices toward a local average, reducing high‑frequency bumps.
• Improves fairness without rebuilding geometry from scratch.
• Works on curves, NURBS surfaces (via control points), meshes, and SubD control cages.

When to use it:

• After intensive point edits, Booleans, or imported geometry that feels “wobbly.”
• Before Loft/Sweep/NetworkSrf to ensure input curves are clean and consistent.
• Before analysis (Zebra, CurvatureGraph) to stabilize highlights and curvature flow.
• On scan‑derived meshes to reduce chatter prior to reverse‑engineering.

Core workflow (best practice):

• Curves and NURBS
  • Turn points on (F10/PointsOn), window‑select interior points, and leave endpoints deselected to keep constraints.
  • Run Smooth with a low Factor (start ~0.1–0.3). Repeat as needed rather than using an aggressive single pass.
  • Restrict axes if necessary (for example, disable Z to retain height).
• Surfaces and polysurfaces
  • Work on a single surface when possible (ExtractSrf) and turn on points.
  • Smooth interior rows; avoid boundaries to maintain edge conditions with neighbors.
  • After smoothing, use MatchSrf (Position/Tangency) to reestablish continuity across joins.
• Meshes and scans
  • Select only the noisy region or vertex ring; leave borders unselected to protect silhouettes.
  • Apply multiple light passes to reduce shrinkage and feature loss.
• SubD
  • Select SubD vertices/edges and Smooth to relax kinks in the control cage.
  • Uncrease edges you want to participate in smoothing; keep critical creases intact.

Options that matter:

• Factor/Strength: small, iterative values provide control and preserve character lines.
• Axis limits (X/Y/Z): prevent unwanted flattening and protect thickness or height.
• Distance limit: cap displacement to avoid drifting features and maintain tolerances.

Troubleshooting and pro tips:

• Edge drift or continuity loss: deselect boundary points and MatchSrf after smoothing.
• Volume loss on organic forms: limit the Z axis, then Pull crucial curves back to reference surfaces.
• Persistent lumpiness: strategically add control (InsertKnot/Rebuild) where density is too low, then Smooth.
• Over‑smoothing: target selections with SelectionFilter and set a conservative distance limit.
• Validate results with CurvatureGraph/Zebra; iterate until highlights flow cleanly.

Pair Smooth with Rebuild/FitCrv for cleaner inputs, and finish with MatchSrf for continuity that passes visual and manufacturing checks. For Rhino upgrades, plugins, and training resources, visit NOVEDGE for Rhino or reach the NOVEDGE team for guidance.

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