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The MatchSrf command adjusts the edge of a surface to have position, tangent, or curvature continuity with another surface.


  1. Select an untrimmed surface edge.
  2. Select a surface edge or curve to match.
    Pick the two surfaces near same ends. This surface can be either trimmed or untrimmed.
  3. Choose options.
Command-line options


Allows selection of more than one edge to match.


When the OnSurface option is on, you can select a curve that is on or near a surface as the target, and then a surface to match to at that curve. The curve is pulled to the surface.

Before match (left); after match (right).


  • The match is to the surface as if the pulled curve were an edge.
  • There is no good way to determine, absent a trim, which way the match should go, so the dialog has a Flip button to control the direction of the match.
  • You can also press Enter to skip selecting a target curve and only select a target surface.
    In that case, the edge to be changed is pulled to the target surface and the pulled curve is used as the target.
  • If the MultipleMatches option is selected, only matching to an edge is allowed.

Helmet - MatchSrf - CrvOnSrf


Selects surface edges that are touching the selected curve.

How to chain select edges.


Type subcrv to select part of a curve as input.

Match Surface Options


Sets the continuity for the match.


Location only.


Position and direction.


Position, direction, and radius of curvature.

Preserve other end

Changes the surface structure to prevent modification of the curvature at the edge opposite the match.


No constraint.


Location only.


Position and curve direction.


Position, direction, and radius of curvature.

Average surfaces

Both surfaces are modified to an intermediate shape. If the target surface is also untrimmed, the surfaces match by averaging the two.

Match edges by closest points

Aligns the surface being changed to the target edge in two ways:

Stretches or compresses the surface to match the entire edge end to end, or pulls each point object on the edge to the closest point object on the other edge.

Refine match

Determines if the match results should be tested for accuracy and refined so the faces match within tolerance. If necessary, Rhino adds knot lines to the modified surface or surfaces until the surfaces are within tolerance.

Distance __ units

Position matching in model units.

Tangency __ degrees

Tangency matching.

Curvature __ percent

Curvature matching, in percent of the radius of curvature.

Flip(OnSurface Only)

Changes the direction of the surface.

Isocurve direction adjustment

Specifies the way the parameterization of the matched surfaces is determined.


If the target edge is not trimmed, it works like the Match target isocurve direction option.

If the target edge is trimmed, it works like the Make perpendicular to the target edge option.

Preserve isocurve direction

Does not change the existing isoparametric curves directions.

Match target isocurve direction

The isoparametric curves of the surface will be parallel to those of the target surface.

Make perpendicular to target edge

The isoparametric curves of the surface will be perpendicular to the target surface edge.


See also


Visually evaluate surface smoothness and continuity using a stripe map.

Edit surfaces

Wikipedia: Tangent




Rhinoceros 8 © 2010-2024 Robert McNeel & Associates. 07-Jun-2024