Rhino 3D Tip: Validate Curvature and Surface Fairness in Rhino

Rhino’s Analyze tools reveal shape quality early, so you can correct issues before they propagate. Use them routinely to validate curvature, ensure continuity, and maintain manufacturable fairness.

Essential curve checks:

• CurvatureGraph: Turn on a curvature comb for selected curves. Aim for smooth, monotonic combs without spikes or sudden length changes. Adjust Scale and Density to read detail without noise.
• Curvature (on curves): Query local radius and curvature direction at a pick point to confirm tight spots, inflection points, and blend quality.
• Section + CurvatureGraph: For surface-based designs, extract diagnostic sections (Section or Contour) and analyze their combs. If sections are fair, surfaces usually follow.

Core surface tools for fairness:

• CurvatureAnalysis: Apply false-color maps (Gaussian, Mean, Min/Max) to visualize domes, saddles, flats, and transitions. Consistent gradients indicate fairness; mottled patterns may signal ripples or knots.
• Zebra and EMap: Reflective stripes or environment maps instantly expose continuity and undulations. Stripes should flow smoothly across edges with no breaks (G0), kinks (G1), or highlight wobble (G2).
• EdgeContinuity: Inspect and quantify G0/G1/G2 at joins. Narrow the tolerance to your production standard to avoid “looks fine” errors that fail downstream.

Practical workflow:

• Block out curves, then Rebuild or FitCrv to reduce unnecessary control points. Fewer, well-placed points create smoother combs and simpler downstream surfaces.
• Create surfaces with Loft, Sweep2, or NetworkSrf using clean rails/sections. Immediately run CurvatureAnalysis and Zebra; fix early if patterns wobble.
• Refine transitions with MatchSrf (Position/Tangent/Curvature). Verify with EdgeContinuity and Zebra; iterate until the diagnostic agrees with your design intent.
• For complex blends, use BlendSrf and then adjust handles while watching Zebra in real time. If highlights breathe or pinch, redistribute CVs or reduce surface degree where appropriate.

Reading the diagnostics:

• Curvature comb spikes = local flat spots or kinks. Smooth by reducing points, redistributing CVs, or using Match on curves.
• Curvature map islands or abrupt color shifts = overbuilt or uneven parameterization. Try Rebuild, RefitSrf, or RemoveMultipleKnots to regularize.
• Zebra breaks at seams = insufficient continuity. Promote to G2 where design allows, or soften transitions with longer blend spans.
• Highlight chatter = too many CVs or uneven spacing. Simplify the input or raise degree judiciously to spread influence.

Production-minded tips:

• Set model tolerance early (Units > Absolute tolerance). Continuity tests are only meaningful against a realistic tolerance.
• Use DraftAngleAnalysis to cross-check manufacturability on parted surfaces.
• Profile-heavy scenes: analyze in simple display modes and isolate areas to keep viewports responsive.

Explore Rhino licenses, training, and expert insights at NOVEDGE. For professional guidance on tool selection or hardware, connect with the NOVEDGE team and elevate your curvature analysis workflow.